Over the last few years, tremendous improvements of device performance and reliability have been demonstrated in devices grown on blanket Si substrates. Recently, electrically pumped QD lasers deposited in narrow oxide pockets in a butt-coupled configuration and on-chip coupling have been realized on patterned Si photonic wafers. However, the device yield and reliability, which ultimately determines the scalability of such technology, are limited by the material uniformity. Here, we perform the detailed analysis on the material anisotropy induced by the pocket geometry. Both the QD morphology and defect configuration anisotropy suggest that all pockets should be aligned to the [1 -1 0] direction of the III-V crystal. The 300 mm growth template consists of rectangular oxide pockets both “parallel” and “orthogonal” with respect to the Si substrate step edges, shown in Figure 1(a) and (b). The room temperature photoluminescent (PL) spectra of the as-grown in-pocket QD laser material, shown in Figure 1(d), indicate that QD quality is higher in the “orthogonal” and wider pockets. The corresponding laser performance, shown in Figure 1(e), suggesting the gain from the QDs in the narrower “parallel” pockets is not high enough for lasing. Representative PL intensity maps of a “half-laser” structure and the corresponding atomic force microscopy (AFM) image of the exposed active region dots are shown in Figure 1(f). The drastic discrepancy of the emission uniformity and QD density between the materials in the wider “orthogonal” pocket and the narrower “parallel” pockets are attributed to asymmetric indium adatom diffusion, with [1 -1 0] being the fast diffusion direction. To map the crystal orientation onto the pocket orientation, faceted trenches (FTs), which would form when a GaAs layer experience abrupt tensile relaxation, were introduced in the pocket with the test structure shown in Figure 2(a). Nomarski images show that FTs elongate along the “orthogonal” pocket, confirming that “orthogonal” pockets are in the [] orientation with respect to the III-V crystal, shown in Figure 2(b) and (c). Thus, aligning the pocket to the fast diffusion orientation would prevent indium adatoms from diffusing onto the edges. Since the edge of the III-V strip is stress free, it is also expected that the residual thermal stress state of the in-pocket materials would also be highly anisotropic with the direction along the short edge of the strip experiencing lower residual tension. It has previously been confirmed that the misfit dislocations (MDs) generated from the residual thermal stress is responsible for device degradation. Such stress anisotropy introduced by the pock geometry could then be utilized to reduce the MD density. Two TEM foils were prepared parallel (“‖”) and perpendicular (“⊥”) to a 20 µm [1 -1 0] oriented pocket, shown in Figure 2(d). Comparing to Figure 2(e) where foil oriented parallel to the pocket, the foil perpendicular to the pocket, shown in Figure 2(f), has a significantly lower density of misfit dislocations, even much lower than those measured in blanket substrate materials. It has previously been found that the MDs in the [1 -1 0] direction formed via tensile relaxation have a Ga-core structure, which resides closer to the middle of the GaAs/AlGaAs bandgap than the MDs in the [1 1 0] direction Though the MDs along the long edge of the pocket would be reduced regardless of the alignment of the pocket with respect to the III-V crystal, all pockets should be aligned to the [1 -1 0] direction to effectively lower the density of the most detrimental defects. The in-pocket devices would then potentially surpass the performance of the state-of-the-art devices grown on blanket Si substrate.

Quantum Dot Morphology and Defect Configuration Anisotropy for III-V Laser Material Grown on Patterned Si Photonic Wafers

GaN-based light emitting diodes (LEDs) for white light illumination are one of the biggest technological achievements in energy efficiency. However, challenges remain with GaN-based LEDs such as efficiency droop and low efficiency for longer wavelengths. Auger-Meitner recombination, a three-carrier process, has been identified as the dominant mechanism for efficiency droop via electron emission spectroscopy (EES). In EES, LEDs were activated to negative electron affinity (NEA) to allow for the emission of hot electrons from the surface which were quantitatively correlated to Auger-Meitner recombination processes. In recent years, V-defects have been proposed as the solution to the excess driving voltage of long wavelength nitride-based LEDs, one of the sources of their diminished efficiency. One way to image the effects of V-defects is using electron emission microscopy (EEM). EEM is a newly developed technique analogous to EES that allows for spatially resolved microscopy of hot electrons. EEM uses a low energy electron microscope with its illumination column turned off, such that only internally generated electrons escaping out the surface during electrical driving of the device are observed. Commercial blue (λ ≈ 460 nm) and green (λ ≈ 525 nm) LED wafers from Seoul Viosys were acquired and processed into LEDs. The diodes were formed by Pd/Au (20/30 nm) p-contacts with open circular and hexagonal apertures lithographically defined with known dimensions. A C-shaped n-contact partially surrounding the p-contact was formed by reactive ion etching into the n-region and contacted with Ti/Au (30/300 nm). EEM was performed in an ELMITEC LEEM III system modified to allow for electrical biasing of devices from the sample stage, where Cs was deposited onto the sample using a SAES Getters Cs source to activate the sample to NEA. For LEDs, EEM images the non-radiatively-recombined electrons that cross the diode junction and diffuse through the p-GaN and escape out the surface, which can include overflow, Auger-Meitner, and trap-assisted Auger-Meitner electrons. EEM images of blue and green LEDs show non-electron emitting regions (dark spots) with densities of ~2 × 107 cm-2 and ~3 × 108 cm-2, respectively, which we identify as V-defects. This is confirmed through the corresponding dark spots of panchromatic CL measurements of the same samples, as well as SEM and plan-view TEM for V-defect densities. Since the density and dimensions of the non-electro-emitting and non-illuminating regions are identical, we attribute our measured lack of electron emission directly from the V-defect areas to electrons fast traveling through the sidewalls of the V-defects and being injected laterally and efficiently into planar quantum wells without any Auger-Meitner recombination or overflow within the sidewalls. This is supported by the stronger electron emission observed at the ridge of the V-defects due to larger carrier densities there and thus increased hot electrons generation. Our results agree with simulations that electrons travel up the sidewalls of V-defects that have been nucleated prior to the active region and directly inject themselves into the quantum wells in the active region, so the carrier density in these sidewalls is negligible [1]. Support at UCSB was provided by U.S. Department of Energy under the Office of Energy Efficiency & Renewable Energy (EERE) Award No. DE-EE0009691. [1] C.-H. Ho, J. S. Speck, C. Weisbuch, and Y.-R. Wu. Phys. Rev. Appl. 17, 014033 (2022).

Electron Emission Microscopy of an Electrically Driven III-Nitride-Based LED: Evidence of Lateral Electron Injection at V-Defect Sidewalls

This abstract explores the possibility of employing metal additive microfabrication of system in package (SiP) with inbuilt heat sinks and leadframe consisting of multiple pads for QFN packaging. The SiPs were fabricated using 17-4Ph stainless steel powder employing a relatively less expensive DMLS system. The use of affordable metal additive manufacturing systems is considered by the authors to encourage further research on its applicability towards heterogenous integration in the semiconductor industries. The International Technology Roadmap for Semiconductors (IRTD) 2012 emphasized on the importance of integration of system on chip (SoC) and SiP. DMLS is one possibility for such heterogenous integration due to the possibility of customization as the parts are directly fabricated from a CAD file. DMLS has been considered superior to its plastic or resin-based counterparts in applications where conductive parts with better accuracy and strength are required. All these features make DMLS parts, a possible option for the fabrication of SiP with few functionalities like heat sinks and connectivity. 3D packaging and heat extraction for die is one of the grand challenges of International Roadmap for Devices and Systems (IRDS). In this abstract, different QFN leadframes with and without cooling systems are presented. The original leadframe design with only the pads forms a comparison reference for the remaining three systems. The three systems are: QFN leadframe with microchannel, inlet, and outlet for fluid flow, QFN leadframe with arrays of fins below the die location, and a QFN leadframe with fins along with additional inlet and outlet for optional fluid flow. Figure 1 shows the CAD top views of all four proposed package system. Each package system can hold a 1cm by 1cm semiconductor die for testing purposes. The microchannels are 500um square channels whereas the fins are 1000um in diameter. The affordability comes with the trade-off of resolution and the present DMLS system can faithfully produce the mentioned dimensions with compatible features for the channels and fins. The first step towards the fabrication of the packages is the CAD design and simulation. The CAD design was then fed to the metal 3D printer, which then sliced the model and created 3D laser part. The fabrication proceeds by melting and fusing a 30um layer of powder, repeating the process, creating layers on top of layers, and fusing them together until the final 3D part is built as per the CAD file. EDM wire cutting or grinding of previously created support structure could be used to separate the parts from the build plate. Figure 2 shows the steps involved in fabrication. On each separate parts, 1cm by 1cm semiconductor dies (all same) are carefully placed. Wire bonding will be used to connect the via to the leadframe pads and inlets/outlets will be extended. The whole system will then be covered with epoxy and left to cure. The final step will be to grind away the back end of the cured part to remove support metal plate on the bottom of the packaging parts as shown in Figure 3. Figure 4 shows the separated parts with a spot for semiconductor die to be affixed and various other sub-parts. Figure 5 shows the water (colored for visibility) filled leadframe with microchannel, and the other one with fins, inlet, and outlet is shown in Figure 6. Figure 7 shows the preliminary infra-red image of all four devices heated to 40°C and left to cool down. The devices were in the same order as Figure 4. As per the theoretical idea, fins with channels performs the best followed by the one with microchannel, and the one with only fins based on the time required for them to cool down (a-f in Figure 4). The preliminary result appears promising and the material characterization along with testing is in process. Figure 8 and 9 shows the SEM characterization of build device compared to the design. The variation from the design is very small.

Additive Microfabrication of System in Package for Heterogenous Integration with Semiconductor Dies

It was both theoretically and experimentally proved that the growth of In Ga 4-xN quantum wells (QWs) on In Ga,_ N underlayer (x > y) would significantly improve the light emitting diodes (LEDs) performance, attributing to the reduction of non-radiative recombination centers, the decline of the internal electrostatic field, and the improvement of indium composition uniformity in QWs. Moreover, the reduced lattice mismatch between QWs and underlayer greatly suppresses composition pulling effect, which improves indium incorporation rate grown at the same temperature, resulting in In-rich InGaN with highly crystalline. However, to serve as templates for red emission QWs, a thicker InGaN pseudo-substrate with closer indium mole fraction to QWs grown beyond the critical layer thickness is desired. In this work, we present an approach to achieve a sub-micron size InGaN underlayer with high to 30 % indium composition, while the thickness is around 90 nm, far exceeding the critical layer thickness of such In-rich InGaN layer on planar c-plane GaN (reported less than 5 nm). The InGaN platelet is demonstrated by selective area growth (SAG) on arrays of GaN seed from circle openings with a diameter of 400 nm ina SiN, mask. To our best knowledge, SAG of InGaN results in random nucleation and uneven shape due to the low diffusion length of gallium precursor at relatively low growth temperature. It was reported that the selectivity of InGaN can be enhanced by introducing pyramid shaped GaN seed first, resulting in InGaN pyramid. However, the local indium composition fluctuation on the semipolar facet of the InGaN pyramid hinders pure red emission of QWs with small full width at half maximum (FWHM). In this work, planar hexagonal shape of GaN seed was introduced first before SAG of InGaN, leading to the formation of uniform InGaN platelets with c-plane domain morphology. The optical properties of the InGaN platelets were characterized by photoluminescence (PL, excited by a He-Cd laser of 325 nm, 15 mW, room-temperature), showing PL peaks around 530 nm with FWHM of 141 meV, suggesting around 30 % indium incorporated. AFM scan of the top c-plane surface of the InGaN platelet indicates an atomically flat surface without v-pits or trench defects while the thickness is over 90 nm. Cross-sectional TEM characterization of InGaN platelet suggests homogenous crystalline and shape interface between InGaN and GaN seed. According to localized EDX line measurements recorded with the same area, the InGaN platelet shows indium composition almost linearly increased from InGaN/GaN interface to c-plane surface. Detailed line profiles show indium composition of 25 % to 30 % at the top surface and 15 % to 20 % at InNGaN/GaN interface. Such high indium-content InGaN platelets are competitive candidates for the development of high-quality yellow-to-red emission InGaN micro-LED, by increasing the indium incorporation rate and reducing the lattice mismatch for later Inrich quantum wells.

High In-Content InGaN Platelets as Underlayer for Light-Emitting Diodes Toward Long Wavelength Application

Ge has a nearly direct bandgap because the direct I valley (k = 0 in momentum space) is only 140 meV above the indirect L valley. Tensile strain (>2%) and alloying (Ge, _,Sn, or Ge, _ C_) are the two most common approaches to make Ge-based direct bandgap materials . Although Ge 4-0" becomes a direct bandgap material with x>10%, Strained growth on Ge or GaAs adds undesirable compressive strain’. Worse, the very small electron effective mass (m, = 0.02m9) loses the direct bandgap when confined in a quantum well (QW) or dot®. Our group has previously demonstrated that Ge, C. with y = 1% has a direct bandgap, and reported GeC using a special precursor (4GeMe) as a C source in molecular beam epitaxy (MBE), with no defects detected in transmission electron microscopy (TEM) ’~. In this work, we instead grew Gey ySnC using a simpler C precursor. GeSnC adds additional control in epitaxial growth: Sn and C partially compensate local strain and distortion of the host Ge bonds. Ab-initio calculations predict that C-Sn-C bonding would be energetically favorable over C-C bonds in the Ge lattice. This is likely to increase both C and Sn substitutional incorporation and provides a more stable material, similar to InGaAs:N . We saw no evidence of Sn segregation as surface droplets, nor C incorporation as undesirable C-C or C=C bonded nano-clusters. Therefore, adding Sn might reduce the carbon clustering at the surface which would be a great achievement compare with past growths by other groups. As an added benefit, GeC offers a larger electron effective mass (Mop): which would preserve the direct bandgap in GeSnC even when confined in a QW. Tensile strained Ge Sn Cy. was grown on GaAs (004) substrate in hybrid MBE using thermal Ge, Sn sources and commercial carbon tetrabromide (CBr) as the carbon source. We believe sp2 C-C pairs are likely defects in the carbon containing alloys, so we also used hydrogen to preferentially remove sp2 carbon, as is done in growth of epitaxial diamond. High resolution x-ray diffraction (HRXRD) reveals good crystallinity in the epi-layer with maximum 3% of substitutional carbon and 4% tin. Raman observation of the C local mode at 530 cm confirms substitutional incorporation into the crystal. Atomic Force Microscopy (AFM) shows mostly flat surfaces. Unlike most other carbon sources, no sp2 (graphitic) or amorphous carbon bonds were detected in Raman spectroscopy from 1200-1600 om”! (not shown). The successful incorporation of C into Ge substitutionally, without cluster carbon, is a major step toward efficient Group IV lasers for silicon photonics. We have also observed emissions in 0.50-0.60 eV range both from bulk and multiple quantum well (MQW) GeSnC samples. These peaks could be from different atomic arrangements, from defects, or from non-uniform QW compositions. The detailed origins of the emission spectrum are currently under investigation and will be reported at the conference. Reference 1. Jifeng Liu, Photonics 1 (3), 162 (2014) 2. G. Grzybowski, R. T. Beeler, L. Jiang, D. J. Smith, J. Kouvetakis, and J. Menéndez, Applied Physics Letters 101 (7), 072105 (2012) 3. M. P. Polak, P. Scharoch, and R. Kudrawiec, Journal of Physics D: Applied Physics 50 (19) (2017) 4. C. A. Stephenson, W. A. O'Brien, M. W. Penninger, W. F. Schneider, M. GillettKunnath, J. Zajicek, K. M. Yu, R. Kudrawiec, R. A. Stillwell, and M. A. Wistey, Journal of Applied Physics 120 (5) (2016) 5. C. A. Stephenson, W. A. O'Brien, M. W. Penninger, W. F. Schneider, M. Gillett-Kunnath, J. Zajicek, K. M. Yu, R. Kudrawiec, R. A. Stillwell, and M. A. Wistey, Journal of Applied Physics 120 (5) (2016). 6. Vincenzo Lordi, Homan B. Yuen, Seth R. Bank, Mark A. Wistey, James S. Harris, and Stephan Friedrich, Physical Review B 71 (12) (2005)

Molecular Beam Epitaxy Growth of Highly Tensile Strained GeSnC Alloys up to 4% Sn and 3% C

In recent years, oxide electronics has emerged as one of the most promising new technologies for a variety of electrical and optoelectronic applications, including next-generation displays, solar cells, batteries, and photodetectors. Oxide electronics have a lot of potential because of their high carrier mobilities and ability to be manufactured at low temperatures. However, the preponderance of oxide semiconductors is n-type oxides, limiting present applications to unipolar devices and stifling the development of oxide-based bipolar devices like p-n diodes and complementary metal-oxide—semiconductors. We have contributed to oxide electronics, particularly on transition metal oxide semiconductors of which the cations include In, Zn, Sn and Ga. We have integrated these oxide semiconductors into thin film transistors (TFTs) as active channel layer in light of the unique combination of electronic and optical properties such as high carrier mobility (5-10 cm“/Vs), optical transparency in the visible regime (>~90%) and mild thermal budget processing (200-400°C). In this study, we achieved four different results. The first result is that unlike several previous reports on oxide p-n junctions fabricated exploiting a thin film epitaxial growth technique (known as molecular beam epitaxy, MBE) or a high-powered laser beam process (known as pulsed laser deposition, PLD) that requires ultra-high vacuum conditions, a large amount of power, and is limited for large-area processing, we demonstrate oxide-based heterojunction p-n diodes that consist of sputter-synthesized p-SnOx and n-IGZO of which the manufacturing routes are in-line with current manufacturing requirements. The second result is that the synthesized p-SnOx films are devoid of metallic Sn phases (i.e., sn? state) with carrier density tuneability and high carrier mobility (> 2 cm2/Vs). The third result is that the charge blocking performance of the metallurgical junction is significantly enhanced by the engineering of trap/defect density of n-IGZO, which is identified using photoelectron microscopy and valence band measurements. The last result is that the resulting oxide-based p-n heterojunction exhibits a high rectification ratio greater than 10° at +3 V (highest among the sputter-processed oxide junctions), a low saturation current of ~2x10 © A, and a small turnon voltage of ~0.5 V. The outcomes of the current study are expected to contribute to the development of p-type oxides and their industrial device applications such as p-n diodes of which the manufacturing routes are in-line with the current processing requirements. Reference: 1. Lee, S.; Paine, D. C., Metallization selection and the performance of amorphous In-Zn-O thin film transistors. Applied Physics Letters 2014, 104 (25), 252103. 2. Liu, M.; Kim, H.; Wang, X.; Song, H. W.; No, K.; Lee, S., Carrier Density-Tunable Work Function Buffer at the Channel/Metallization Interface for Amorphous Oxide Thin-Film Transistors. ACS Applied Electronic Materials 2021, 3 (6), 2703-2711. 3. Chu, X., Zhuang, S., Chi, C., Xu, H., Du, G., Dong, X., & Yin, J. (2017). Study on the electroluminescence properties of the P-nimgo:Li/mgo/n-zno nanowires/ito heterojunction. Journal of Luminescence, 187, 486-491. 4. Kawazoe, H.; Yanagi, H.; Ueda, K.; Hosono, H., Transparent p-Type Conducting Oxides: Design and Fabrication of p-n Heterojunctions. MRS Bull. 2000, 25 (08), 28-36. 5. Mo, X., Fang, G., Long, H., Li, S., Wang, H., Chen, Z., Huang, H., Zeng, W., Zhang, Y., & Pan, C. (2014). Unusual electroluminescence from n-ZnO@i-MgO core-shell nanowire color-tunable light-emitting diode at reverse bias. Phys. Chem. Chem. Phys., 16(20), 9302-9308. 6. Nomura, K.; Ohta, H.; Takagi, A.; Kamiya, T.; Hirano, M.; Hosono, H., Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors. Nature 2004, 432 (7016), 488-492.

Facile Processing and Properties of P-Type SnOx and Oxide-Based p-n Heterojunction Application with n-InGaZnO

As the complexity of flexible electronic devices such as displays and sensors has increased, new plastic-compatible manufacturing methods are becoming necessary to produce high-yield, low-defect flexible circuits. While solution-processed methods such as printing can be used to fabricate circuits on low-temperature substrates, printing is not always a feasible option to realize complex, high-density circuits with small devices. In particular, highresolution display applications typically require single-micron feature sizes and excellent uniformity over large-area substrates. For these applications, more precise fabrication techniques such as photolithography are required. However, due to the poor dimensional stability of polymers, even low-temperature processes such as soft bakes during lithography can alter the substrate dimensions. The problem of dimensional stability can be overcome by attaching the polymer film to a rigid carrier during device fabrication, then releasing the polymer substrate with the fully fabricated device layer on top. For this reason, the separation of polymer films from rigid carriers remains a crucial step in creating next-generation flexible electronics. In this talk, we will discuss a large-area, high-throughput photonic lift-off (PLO) process to rapidly separate polymer films from rigid carriers. PLO uses broadband light (200 nm — 1100 nm) from a flashlamp to lift off a polymer film from a rigid carrier coated with a light-absorbing layer (LAL), where the polymer film may contain functional devices [1]. Compared to a raster process such as excimer laser lift-off, the PLO process is advantageous as it can enable large area lift-off (150 mm x 75 mm) in one flash of light lasting between 100- 200 us, thus enabling higher throughput. Furthermore, the LAL prevents direct illumination of the polymer substrate during lift-off and facilitates cleaner lift-off without polymer ashing. The LAL also makes PLO a polymer-agnostic process, enabling lift-off of a wide range of polymers. We will discuss our recent work fabricating flexible thin-film transistors (TFTs) using PLO [2]. Polyimide with a low coefficient of thermal expansion (CTE) was used to minimize residual film stress. Indium zinc oxide (IZO) TFTs were fabricated on the polyimide films and subsequently released from the carrier using PLO. The released devices demonstrated no significant changes after the PLO process, yielding a mobility of ~3 cm“V_s__ before and after liftoff. The flexible TFTs were robust to bending stress, showing no notable decrease in mobility while bent with a 10 mm radius of curvature. When combined with the ability to successfully separate the PI from the carrier, the low-CTE PI creates a robust fabrication platform for flexible electronics that allows conventional patterning and deposition techniques to be used on a plastic substrate while maintaining dimensional stability with processing temperatures up to 380 °C. A 3D finite element model indicates that the polymer/LAL interface reaches above 800 °C during PLO, but the top surface of the PI remains below 120 °C. The model shows that the maximum temperature at the device layer during PLO is strongly impacted by the thickness and material properties of the polymer film, highlighting the value of the model to guide PLO device design. This work demonstrates the feasibility of PLO to successfully release polyimide substrates containing flexible electronic devices from glass carriers after withstanding conventional lithographic processing methods. [1] R. Hendriks and K. A. Schroder, “Method for performing delamination of a polymer film. U.S. Patent 10,011,104.,” U.S. Patent 10,011,104, Jul. 03, 2018 [2] A. M. Weidling, V. S. Turkani, V. Akhavan, K. A. Schroder, and S. L. Swisher, “Large-Area Photonic Lift-off Process for Flexible Thin-Film Transistors,” in press.

Large-Area Photonic Lift-off Process for Flexible Thin-Film Transistors

High-brightness photoemitters can be employed as electron sources in ultrafast electron diffraction and X-ray free-electron lasers, energy recovery linacs, electron microscopes, electron beam lithography, space propulsion and high-power microwave devices. To yield high quantum efficiencies, high brightness beams require rapid response times and low mean transverse energies (MTE). Recently, negative electron affinity (NEA) photocathodes, consisting of a GaAs wafer and a Cs/O surface layer, have been reported to exhibit both reasonably low MTE and good external quantum efficiencies (EQE) of ~10 ~-10 “. However, NEA cathodes are rarely used due to their significantly complex fabrication process which includes high temperature processing steps, entirely in-situ activation as well as ultra-high vacuum storage and operating pressures. Their stability is not also up to the mark. In this investigation, we have fabricated a Hot Electron Laser Assisted Cathode (HELAC) using electronically tunable negative electron affinity silicon surface. Briefly, the device consists of a three-layer stack of (i) a semiconductor, which absorbs incident photons, (ii) a monolayer of graphene, which acts as the gate, and (iii) an insulator, which allows a voltage drop between the semiconductor and graphene. In this device, an electric field is generated by applying a bias voltage between the semiconductor and graphene which mimics the surface dipole field in an NEA photocathode. Electrons injected into the graphene do not require transport to the emitting surface due to the monolayer thickness of the graphene. This device is air stable with a simple ex-situ fabrication flow while preserving the advantages of NEA photocathodes. We have demonstrated an initial proof-of-concept HELAC device with a psilicon substrate, silicon oxide insulator and monolayer graphene stack and evaluated its performance using a 405 nm CW laser at ~40 mW of incident power. Despite having a non-optimized structure, this device has exhibited a current of ~70 yA (~1.1 mA/cm?), resulting in an EQE of ~0.5%. Semiconductor modeling indicated that EQEs of ~10% and response times in the 1-10 ps range are plausible for this device. Additionally, it is expected that low-MTE is achievable by optimizing the quality of the insulator, the barrier height, and the tunneling mechanism. This is analogous to Cs-based NEA devices, where low MTEs are attainable despite a large electric field which is developed due to the surface dipole.

Hot Electron Laser Assisted Cathode using Electronically Tunable Negative Electron Affinity Silicon Surface

B-phase MgGaO ternary alloy thin films of different Mg compositions were grown by using oxygen plasma assisted molecule beam epitaxy (MBE). The atomic ratios of Mg and Ga in sample A, B, and C were recorded as 11.15 at.%/88.85 at.%, 23.29 at.%/76.71 at.%, and 36.35 at.%/63.65 at.%, respectively, which were measured by energy-dispersive X-ray (EDX) spectroscopy. The samples were characterized by a scanning electron microscope (SEM), showing that the surface becomes rougher in samples with higher Mg contents. Three typical monoclinic structure diffraction peaks located at 19.12°, 38.50°, and 59.14°, which correspond to the B phases of (-201),(-402), and (-603) were investigated by X-ray diffraction (XRD), and all these diffraction peaks exhibit an obvious blue shift compared with that of reference B-Ga,0.. Raman spectra were investigated by a confocal Raman microscope equipped with a high-resolution laser centered at 532 nm with a power of 60 mW. Four out of ten A_ and four out of five B_ Raman-active optical phonon modes were observed. The reduced peak intensity of A (2)(9) A (10) B (2)- (3), and B 8 indicates that Mg * atoms have replaced the position of Ga * ions in both octahedral and tetrahedral chains. The ultra-wide bandgap absorption and transmittance spectra were measured using a UV-Vis-NIR spectrophotometer. Ultra-wide bandgaps of 4.98, 5.05, 5.20, and 5.30 eV were measured for pure Ga,0x, sample A, B, and C, respectively with all transmittances of light over 80% in the visible spectrum region. Temperature-dependent photoluminescence (PL) spectra were investigated by a 325-nm laser with temperatures ranging from 13 to 300 K, revealing only intermediate level transitions, which decrease with the increase of temperature. A MSM solar-blind ultraviolet photodetector (PD) was fabricated based on MgGaO films with Pt/Au electrodes. Photoresponse has been studied by typical dark and irradiated wavelength dependent I-V curves.

Characterization of β-Phase MgGaO Thin Films Grown by Molecular Beam Epitaxy

Based on a mechanical analog to a particle trapping technique, the Paul trap, a lab has been developed to train scientific thinking and experimental problem-solving. It also works to illustrate an important concept in many areas of modern physics. The mechanical trap will together with a simulation give students an introduction to the concept of particle trapping. The lab has been developed to contribute to the ever-important task of making high school physics more interesting, to get more students pursuing careers in STEM, and increasing scientific literacy in the public. Using a design-based approach to developing the lab, its effectiveness on student learning and interest is probed using qualitative and quantitative methods, and initial findings from the study will be presented.</p>

The Mechanincal Rotating Saddle Trap in High School Physics Education

I will report the results of using student&nbsp;story-telling as a pedagogical&nbsp;technique&nbsp;&nbsp;in physics that I have&nbsp; applied&nbsp;to&nbsp;four college courses: a two-semester Introductory Physics course, Modern Physics, and Statistical Mechanics. Students were asked to research biographies of physicists and present 5-7 minute summaries that went beyond a narration of facts and events but provide context and connections. Students were asked to focus on what motivated physicists to study physics, what challenges they faced, their contributions and hobbies apart from physics, and how they interacted with other scientists in their time.&nbsp;A special effort was made to promote story-telling of the background and contributions of women and minorities in physics. I will report on student&nbsp;responses and reactions to this effort, based on blind surveys,&nbsp;exam results&nbsp;and&nbsp; general observations.</p>

Student Storytelling in Physics Courses to Promote Engagement and Diversity

Controlling light-matter interaction with molecular vibrations in mid-infrared resonators offers exciting new research opportunities in chemistry and physics [1]. Laboratory implementations use standard materials, operate at room temperature, and use traditional fabrication and detection techniques, yet they have deeply challenged our fundamental understanding on the connections between cavity quantum electrodynamics and chemistry. We have developed rigorous microscopic quantum theory to describe the optical and chemical properties of realistic molecular vibrations in infrared cavity resonators with non-perturbative light-matter interaction [2,3]. We can successfully describe the linear and nonlinear spectra of vibrational polaritons [4]—hybrid vibration-cavity eigenstates– and realistically study the dissociation dynamics of cavity-coupled molecular bonds under non-adiabatic conditions [5]. The role of symmetry of the ground state electronic density with respect to nuclear displacements in the dynamics of vibrational polaritons is discussed, and future applications of these systems for the generation of THz quantum light are suggested.

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Quantum Dot Morphology and Defect Configuration Anisotropy for III-V Laser Material Grown on Patterned Si Photonic Wafers

Electron Emission Microscopy of an Electrically Driven III-Nitride-Based LED: Evidence of Lateral Electron Injection at V-Defect Sidewalls

Additive Microfabrication of System in Package for Heterogenous Integration with Semiconductor Dies

High In-Content InGaN Platelets as Underlayer for Light-Emitting Diodes Toward Long Wavelength Application

Molecular Beam Epitaxy Growth of Highly Tensile Strained GeSnC Alloys up to 4% Sn and 3% C

Facile Processing and Properties of P-Type SnOx and Oxide-Based p-n Heterojunction Application with n-InGaZnO

Large-Area Photonic Lift-off Process for Flexible Thin-Film Transistors

Hot Electron Laser Assisted Cathode using Electronically Tunable Negative Electron Affinity Silicon Surface

Characterization of β-Phase MgGaO Thin Films Grown by Molecular Beam Epitaxy

The Mechanincal Rotating Saddle Trap in High School Physics Education

Student Storytelling in Physics Courses to Promote Engagement and Diversity

Strong light-matter coupling with molecular vibrations in infrared resonators

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