Ultra-violet light emitting diodes (UV-LEDs) and lasers based on the III-Nitride material system are very promising since they enable compact, safe, and efficient solid-state sources of UV light for a range of applications. The primary challenges for UV LEDs are related to the poor conductivity of p-AlGaN layers and the low light extraction efficiency of LED structures. Tunnel junction-based UV LEDs provide a distinct and unique pathway to eliminate several challenges associated with UV LEDs[1-4]. In this work, we present for the first time, a reversed-polarization (p-down) AlGaN based UV-LED utilizing bottom tunnel junction (BTJ) design. We show that compositional grading enables us to achieve the lowest reported voltage drop of 1.1 V at 20 A/cm2 among transparent AlGaN based tunnel junctions at this Al-composition. Compared to conventional LED design, a p-down structure offers lower voltage drop because the depletion barrier for both holes and electrons is lower due to polarization fields aligning with the depletion field. Furthermore, the bottom tunnel junction also allows us to use polarization grading to realize better p- and n-type doping to improve tunneling transport. The epitaxial structure of the UV-LED was grown by plasma-assisted molecular beam epitaxy (PAMBE) on metal-organic chemical vapor deposition (MOCVD)-grown n-type Al0.3Ga0.7N templates. The transparent TJ was grown using graded n++-Al0.3Ga0.7N→ n++-Al0.4Ga0.6N (Si=3×1020 cm-3) and graded p++-Al0.4Ga0.6N →p++-Al0.3Ga0.7N (Mg=1×1020 cm-3) to take advantage of induced 3D polarization charges. The high number of charges at the tunnel junction region leads to lower depletion width and efficient hole injection to the p-type layer. The UV LED active region consists of three 2.5 nm Al0.2Ga0.8N quantum wells and 7 nm Al0.3Ga0.6N quantum barriers followed by 12 nm of p- Al0.46Ga0.64N electron blocking layer (EBL). The active region was grown on top of the tunnel junction. A similar LED with p-up configuration was also grown to compare the electrical performance. The surface morphology examined by atomic force microscopy (AFM) shows smooth growth features with a surface roughness of 1.9 nm. The dendritic features on the surface are characteristic of high Si doping on the surface. The composition of each layer was extracted from the scan by high resolution x-ray diffraction (HR-XRD). The electrical characteristics of a device show a voltage drop of 4.9 V at 20 A/cm2, which corresponds to a tunnel junction voltage drop of ~ 1.1 V. This is the best lowest voltage for transparent 30% AlGaN tunnel junctions to-date and is comparable with the lowest voltage drop reported previously on non-transparent (InGaN-based) tunnel junctions at similar Al mole fraction AlGaN. On-wafer electroluminescence measurements on patterned light-emitting diodes showed single peak emission wavelength of 325 nm at 100 A/cm2 which corresponds to Al0.2Ga0.8N, confirming that efficient hole injection was achieved within the structure. The device exhibits a wavelength shift from 330 nm to 325 nm with increasing current densities from 10A/cm2 to 100A/cm2. In summary, we have demonstrated a fully transparent bottom AlGaN homojunction tunnel junction that enables p-down reversed polarization ultraviolet light emitting diodes, and has very low voltage drop at the tunnel junction. This work could enable new flexibility in the design of future III-Nitride ultraviolet LEDs and lasers. Funding from National Science Foundation under grant number 2034140 is gratefully acknowledged. References: [1] Y. Zhang et al., Applied Physics Letters, vol. 109, no. 12, 2016 [2] A. Pandey, W. J. Shin, J. Gim, R. Hovden, and Z. Mi, Photonics Research, vol. 8, no. 3, 2020 [3] V. Fan Arcara et al., Journal of Applied Physics, vol. 126, no. 22, p. 224503, 2019. [4] K. Nagata et al., Applied Physics Express, vol. 14, no. 8, p. 084001, 2021.

Demonstration of AlGaN Tunnel Junction p-Down UV Light Emitting Diodes

UV-LEDs are in demand for their sterilization properties. Tunnel junction UV-LEDs while solving several challenges of conventional UV-LEDs also provides a method to realize cascaded LEDs. Multi-active region UV-LEDs can enable EQE scaling, multi-wavelength emission and high output power density at reduced cost leading to commercially viable LEDs. Efficient multi-active regions can be achieved by low voltage drop tunnel junctions and optimized active regions. In this work, we demonstrate for the first time, a dual-junction UV-LED, with transparent tunnel junctions.

Multi-Active Region AlGaN Ultraviolet Light Emitting Diodes with Transparent Tunnel Junctions

M: Group III–Nitrides—Optical Emitters

technical paper

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.

EMC is coordinated with the Device Research Conference (DRC). This recognizes the strong interaction between device and electronic materials research and provides fruitful exchange of information between attendees of both Conferences.

EMC 2023

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

**This session will take place on June 27, 2022 at 6:00pm ET. 

Poster Session

poster

[![](https://assets.underline.io/uploads/markdown_image/1/image/985c8a40b04e56675221c8549975de3c.png)](https://drive.google.com/file/d/1B70nPIeeeqdG4UU70NlYXuKVOHLRuJEo/view?usp=sharing)

### ** 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.

Today, as we look forward to the next 75+ years of device innovation, DRC continues to lead the way in showcasing top-caliber research, facilitating vibrant discussion and debate and acting as a platform to nurture the next generation of device engineers. We welcome you to join us at the next DRC!

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**
* Biological Devices
* Devices for Extreme Conditions
* Heterogeneously Integrated Devices
* Memory Devices
* Modeling and Simulation of Devices
* Nanoscale and Vacuum Devices
* Optoelectronic and Optical Devices
* Other Emerging Devices
* Power Devices
* Quantum Devices
* RF and Terahertz Devices
* Spintronic and Magnetic Devices
* Thin-film Devices
* Wide-bandgap Devices
 
### **Invited Speakers**
* Patrick Fay, University of Notre Dame
* Susanne Hoffmann-Eifert, Peter Grünberg Institute
* Sanghyeon Kim, Korea Advanced Institute of Science and Technology
* Sriram Krishnamoorthy, University of California, Santa Barbara
* Mario Lanza, King Abdullah University of Science and Technology
* Xiuling Li, The University of Texas at Austin
* Marko Radosavljevic, Intel Corporation
* Siddharth Rajan, The Ohio State University
* Giordano Scappucci, Delft University of Technology
* Fisher Yu, University of Arkansas
* Wenjuan Zhu, University of Illinois at Urbana-Champaign




Registration is required to attend this event. If you have not already done so, please use the link below to register for a ticket to the conference:

https://www.mrs.org/drc-2022/registration

Registration Is Required

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.

Shamsul Arafin

2

7

Presentations

Demonstration of AlGaN Tunnel Junction p-Down UV Light Emitting Diodes

Multi-Active Region AlGaN Ultraviolet Light Emitting Diodes with Transparent Tunnel Junctions

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