Gallium oxide (Ga2O3) is a conducting transparent semiconducting oxide and ultra-wide bandgap material which allows for a large critical electric field that maximizes frequency and voltage operation. Due to its large Baliga’s figure of merit (3200 * Si) and inexpensive melt-growth methods, Ga2O3 is of interest in electrical and optical applications [1, 2, 3]. β-Ga2O3 is the most chemically and thermally stable phase with an anisotropic bandgap between 4.5 and 4.9 eV, depending on orientation [1, 2, 3]. To control the electrical and optical properties of Ga2O3 and aluminum gallium oxide alloy (AGO) within devices, understanding where their defects come from and how they develop is important. For example, although point defects can be used to control their properties, e.g. doping, extended defects tend to negatively impact their operation. As such, identifying the types of defects caused by growth or fabrication processes is important for developing those processes and reducing undesirable defects. One method to characterize defects is through photoluminescence (PL) which is a noninvasive process. For β-Ga2O3, the PL spectrum is broad over the UV, blue, and green wavelengths making deconvolving the spectra extremely difficult [1, 2]. There have been studies in the literature to determine the origin of the β-Ga2O3 spectra, but those studies typically focus on point defects as a cause [1]. Here, the correlation between sample quality and extended defects is possible with PL and PL Microscopy (PLM). Comparing β-Ga2O3 or AGO films and bulk samples shows that extended defects have an essential role in the PL emission. Homogeneous films with no extended defects and bulk crystals will yield a UV dominant PL emission. Samples of poor film quality that have extended defects throughout will have a dominant blue PL emission. This means the quality of a sample, in terms of the density or extended defects, can be determined through PL [1]. Furthermore, sample topography and extended defects can be identified through PLM [2]. Single crystal samples have uniform UV emission. That said, any topography can alter the emission intensity due to refraction and diffraction. Furthermore, any topography that is altered due to defects also causes a contrast in emission intensity. As such, PLM tends to match AFM and SEM images. But, there are cases where PLM can diverge from AFM and SEM due to other extended defects within the film, which are more luminescent than surface defects/topography. Some defects identified using PLM include cracks running along [001] on AGO films, rotational domains found in β-Ga2O3 grown on sapphire, incoherent stacking faults from (-201) β-Ga2O3 grown on Fe-doped β-Ga2O3, and sympetalous defects which are a newly discovered defect [2]. The sympetalous defect is found on metalorganic vapor-phase epitaxy (MOVPE) films grown on (010) Ga2O3. This defect generally grows out from underlying line defects in the substrate, such as nano-pipes, which is similar to v-defects found in GaN. The defect creates a polycrystalline region in the film, expanding out from the initial starting line defect seed [3]. PL shows that the sympetalous defects are polarization-dependent. Furthermore, circular polarization also shows luminescence likely caused by the defect grains having a semi-helix growth with themselves and/or bulk crystal surrounding the defect [3]. Lastly, the quality of a sample can be determined by looking at the density and surface size range of defects on the surface of a sample. Sympetalous defects are similar in size and have the same density as substrate etch-pits. Nodular defects, on the other hand, have a wide variety of sizes and density that increases with thickness [3]. [1] J. Cooke, et al., Scientific Reports, 12, 3243 (2022). [2] J. Cooke, et al., Optical Material Express, 12 (11), 4341 (2022). [3] J. Cooke, et al., J. Vac. Sci. Technol. A, 41 (1), 013406 (2023).

Characterization Analysis of Extended Defects in β-Ga2O3 and AGO

Emerging Gallium Oxide power semiconductor materials and devices

Photoluminescence (PL) has been under intense scrutiny in an attempt to define the mechanisms that generate the emissions in gallium oxide (Ga,0.). In general, PL spectra is used to characterize the defects leading to radiative recombination processes within a specific material. In this regard, the PL spectra for B-Ga,0, has generally been deconvoluted in three emission peaks: UV, blue, and green. However, peak shapes from any point defect are expected to require more than a single Gaussian for a complex crystal structure like B-Ga,0., possibly having an asymmetric shape and requiring a more complex model, which takes into consideration the vibrational broadening of the PL spectrum due to electron-phonon coupling. The sum of many phonon replicas makes it challenging to fit the spectra uniquely. Adding energy level broadening from disorder or extended defects makes deconvolution of the B-Ga 793 PL spectra even more difficult. As such, there is little chance of being able to spectroscopically discern different types of defects in B-Ga,0, from luminescence as any defect considered can result in a very wide luminescence band, even near 0 Kelvin. This has resulted in an intense debate in defining the defects and phenomenological explanations of electronic processes that cause these particular emissions. In these debates, point defects have been the only explored and discussed potential source for the visible PL emission in B-Ga,0.. But, as far as can be determined, no previous works in the literature have discussed whether extended defects affect PL. Here, a systematic PL study on three series of B-Ga,0, /aluminum gallium oxide films and bulk single crystals is performed. The first series includes three film samples with varying Si-doping: UID (~10 ~cm_~),~10 cm, and ~10'8 om”, All samples in the series are (010) oriented Si-doped B-Ga,0, film grown on Fe-doped B-Ga,0.. The second series contains three samples and compares (-201) B-Ga,0.. This series includes a bulk crystal of (-201) UID B-Ga,0., a (-201) UID B-Ga,0, film grown on Fe-doped B-Ga,0., and a (-201) UID B-Ga,0, film grown on sapphire. The last series compares (010) oriented (Al Ga, _)903 films, i.e., AGO of varying Al concentrations (0%, 10%, and 25%), grown on Fe-doped B-Ga,,O.,,. These are compared to a (100) oriented bulk 10% AGO (B-Alp Ga 2-3 . O,,) crystal. A second part of the series compares (-201) oriented 0%, 2%, 10%, and 28% AGO films grown on 3 sapphire. The Si-doped series yields homogeneous crystalline films with a low density of extended defects [1] and a dominant UV emission in PL. In the (-201) series, the bulk (-201) B-Ga,0, sample also shows a dominant UV emission. On the other hand, Heteroepitaxial and homoepitaxial (-201) B-Ga,0, films show consistent PL features with dominant blue emission. The (-201) films’ poor quality [2, 3] is likely the reason for this shift in the dominant emission, as observed when comparing UID films grown on (010) and (-201) bulk B-Ga,0, crystals with comparable growth conditions. The AGO series shows consistent blue centered PL with no UV emission for both homoepitaxial and heteroepitaxial AGO samples. The AGO films show extended defects throughout a poor-quality film revealed using transmission electron microscopy (TEM) on the 25% AGO grown on (010) bulk B-Ga,0, crystal. Lastly, representative samples chosen from all three series were compared and it is shown that extended defects have an essential role in the PL emission of B-Ga,0., and AGO films. Homogeneous films with no extended defects or stacking faults and bulk crystals will yield a UV dominant PL emission. Samples of poor film quality that have stacking faults and extended defects will have a dominant blue PL emission. 1.8 References: [1] Rafique, S., et al., Appl. Phys. Lett. 108, 182105 (2016). [2] Ghadbeigi, L., et al., Journal of Elec Materi. 50, 2990-2998 (2021). [3] Eisner, B. A., et al., J. Appl. Phys. 128, 195703 (2020).

Effect of Extended Defects on Photoluminescence of Gallium Oxide and Aluminum Gallium Oxide Epitaxial Films

Gallium Oxide is an emerging ultra-wide band gap semiconductor with promising material properties relevant for high performance power electronic devices. State-of-the-art electron mobilities, contact resistance values, breakdown voltages and power figures of merit are demonstrated in β-Ga2O3 epitaxial films and devices.

High Performance Homoepitaxial Gallium Oxide Power Devices on Bulk and Composite Substrates

Late News: High Voltage β-Ga2O3 Lateral Schottky barrier diode with High Permittivity Dielectric RESURF demonstrating > 1 GW/cm2 Power Figure of Merit

CC: Characterization of Gallium Oxide-Based Materials and Devices II

technical paper

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The Electronic Materials Conference (EMC) is the premier annual forum on the preparation, characterization and use of electronic materials. 

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 The IEEE Workshop on Wide Bandgap Power Devices & Applications (WiPDA) provides a forum for device scientists, circuit designers, & application engineers from the Power Electronics & Electron Devices Societies to share technology updates, research findings, experience & potential applications.
 
 **Topics of interest**
* Heteroepitaxial & Bulk Materials Growth
* Gate Dielectrics & Surface Passivation
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IEEE WiPDA 2022

The IEEE Workshop on Wide Bandgap Power Devices & Applications (WiPDA) provides a forum for device scientists, circuit designers, & application engineers from the Power Electronics & Electron Devices Societies to share technology updates, research findings, experience & potential applications.

FF: Gallium Oxide—Material Processing, Characterization and Defects

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EMC 2022

The Electronic Materials Conference (EMC) is the premier annual forum on the preparation, characterization and use of electronic materials. This year’s event will feature a plenary session, topical sessions, a poster session and more.

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 Session Chair: Andy Carter

Session 1 - Wide Bandgap I - Lateral Ga2O3 Devices

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### ** History of DRC**
The Device Research Conference (DRC) began in the pre-transistor era with the 1942 establishment of the Conference on Electron Device Research (CEDR). Following William Shockley’s 1948 CEDR presentation of the transistor device, the Solid-State Device Research Conference (SSDRC) was established, with invitation-only attendance.

In the ensuing decades, many exciting firsts were presented at SSDRC, including the use of impurity diffusion in silicon and germanium, the first practical MOSFET, and the first lattice-matched heterojunction.

In 1969, under the leadership or Herbert Kroemer and Cal Quate, the CEDR and SSDRC merged into DRC. In 1970, attendance was opened to all, and the first DRAM (dynamic random-access memory), room temperature lasers, and first CCD (charge-coupled device) were reported—all in the same 1970 DRC meeting!

1976 saw the first official coordination of tandem meetings between DRC and the Electronic Materials Conference (EMC) to bring together the electronic materials and device communities—a custom which persists to this day. In 1991, DRC began publishing its digest with IEEE; they can all be found [here on IEEE Xplore](https://ieeexplore.ieee.org/xpl/conhome/1000199/all-proceedings). Throughout this period, DRC featured reports of many novel and record-setting devices, including the HEMT (High Electron Mobility Transistor), VCSEL (Vertical Cavity Surface Emitting Laser), HBT (Heterojunction Bipolar Transistor), and nanoscale MOSFETs.

In recent years, DRC has continued to be the world’s premier forum to present innovative semiconductor device research with work on organic thin film transistors, graphene and carbon nanotube transistors, and 2D materials all featuring prominently in the 1990s through to the present day. In 2017, we celebrated DRC’s 75th anniversary with special sessions and an [article in the Journal of the Electron Device Society](https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8168249&isnumber=8232486). DRC technical topics continue to evolve with emerging device trends such as memory devices, quantum devices, optoelectronics/photonics, and wide bandgap power devices to reflect the exciting work being done by a diverse community of device engineers around the globe.

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To learn more about DRC's history, please see [Aaron Franklin, Debdeep Jena and Deji Akinwande, "75 Years of the Device Research Conference—A History Worth Repeating," in IEEE Journal of the Electron Devices Society, vol. 6, pp. 116-120, 2018. doi: 10.1109/JEDS.2017.2780778](https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8168249&isnumber=8232486).

### **Topics**
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* Xiuling Li, The University of Texas at Austin
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DRC 2022

DRC continues to be the world’s premier forum to present innovative semiconductor device research with work on organic thin film transistors, graphene and carbon nanotube transistors, and 2D materials all featuring prominently in the 1990s through to the present day. In 2017, we celebrated DRC’s 75th anniversary with special sessions and an article in the Journal of the Electron Device Society. 
DRC technical topics continue to evolve with emerging device trends such as memory devices, quantum devices, optoelectronics/photonics, and wide bandgap power devices to reflect the exciting work being done by a diverse community of device engineers around the globe.

**Please use the button above to access the live recording.**
 
 Session Chairs: Shaloo Rakheja & Joachim Knoch

Sriram Krishnamoorthy

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SHORT BIO

Presentations

Characterization Analysis of Extended Defects in β-Ga2O3 and AGO

Emerging Gallium Oxide power semiconductor materials and devices

Effect of Extended Defects on Photoluminescence of Gallium Oxide and Aluminum Gallium Oxide Epitaxial Films

High Performance Homoepitaxial Gallium Oxide Power Devices on Bulk and Composite Substrates

Late News: High Voltage β-Ga2O3 Lateral Schottky barrier diode with High Permittivity Dielectric RESURF demonstrating > 1 GW/cm2 Power Figure of Merit

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