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P22. A polarization-induced 2D hole gas in undoped gallium nitride quantum wells

Science (2019) [Direct download link]

R. Chaudhuri, S. Bader, Z. Chen, D. Muller, H. Xing, D. Jena

Featured in Cornell Chronicle, Semiconductor Today, EurekaAlert!, ScienceDaily,

(Editor's Feature) A Hole Flatland :

When two distinct materials are placed on top of each other, the difference in polarization between the two layers can induce charge carriers at the interface. Many such two-dimensional (2D) electron gases have been observed, but engineering a 2D hole gas without the help of doping has been much trickier. Chaudhuri et al. used molecular beam epitaxy to grow a layer of gallium nitride on top of aluminum nitride without introducing dopants. This approach resulted in a high-density 2D hole gas at the interface in this technologically relevant system.

P21. Very High Density (>10^14 cm−2 ) Polarization-Induced 2D Hole Gases Observed in Undoped Pseudomorphic InGaN/ AlN Heterostructures

Advanced Electronics Materials (2022)

R. Chaudhuri, Z. Zhang, H. Xing, D. Jena

Building on the recently discovered undoped, polarization-induced GaN/AlN 2D hole gas (2DHG), this work demonstrates the tuning of the piezoelectric polarization difference across the heterointerface by introducing indium in the GaN channel. Using careful design and epitaxial growths, these pseudomorphic (In)GaN/AlN heterostructures result in some of the highest carrier densities of >10^14 cm−2 in a III-nitride heterostructure—just an order below the intrinsic crystal limit of ~10^15 cm−2 . A characteristic alloy fluctuation energy of 1.0 eV for hole scattering in InGaN alloy is proposed based on the experiments.

P20. in-situ crystalline AlN Passivation for Reduced RF Dispersion in strained-channel AlN/GaN/AlN HEMTs

physica status solidi (a) (2021)

R. Chaudhuri, A. Hickman, J. Singhal, J. Casamento, H. Xing, D. Jena

Herein, a novel in-situ passivation technique for III-nitride high electron mobility transistors (HEMTs) is demonstrated using a crystalline AlN layer to move the surface states away from the 2D electron gas (2DEG) channel. In-situ passivated AlN/GaN/AlN HEMTs show drastic reduction in DC-RF dispersion of ∼ 2 − 6% compared to ∼ 20% in current state-of-art ex-situ silicon nitride (SiN) passivated AlN HEMTs.

P19. High conductivity Polarization-induced 2D hole gases in Undoped GaN/AlN Heterojunctions enabled by Impurity Blocking Layers

Journal of Applied Physics (2021)

Reet Chaudhuri, Zhen Chen, David A. Muller, Huili Grace Xing, Debdeep Jena

High-conductivity undoped GaN/AlN 2D hole gases (2DHGs), the p-type dual of the AlGaN/GaN 2D electron gases (2DEGs), have offered valuable insights into hole transport in GaN and enabled the first GaN GHz RF p-channel FETs. They are an important step towards high-speed and high-power complementary electronics with wide-bandgap semiconductors. These technologically and scientifically relevant 2D hole gases are perceived to be not as robust as the 2DEGs because structurally similar heterostructures exhibit wide variations of the hole density over ∆ps > 7e13 cm−2 , and low mobilities. In this work, we uncover that the variations are tied to undesired dopant impurities such as Silicon and Oxygen floating up from the nucleation interface. By introducing impurity blocking layers (IBLs) in the AlN buffer layer, we eliminate the variability in 2D hole gas densities and transport properties, resulting in a much tighter-control over the 2DHG density variations to ∆ps ≤ 1 e13 cm−2 across growths, and a 3× boost in the Hall mobilities. These changes result in a 2-3× increase in hole conductivity when compared to GaN/AlN structures without IBLs.

P18. GaN/AlN p-channel HFETs with Imax >420 mA/mm and ~20 GHz f_T / f_MAX

IEEE International Electron Devices Meeting (IEDM) (2020)

K. Nomoto, R. Chaudhuri, S. Bader, L. Li, A. Hickman, S. Huang, H Lee, HW Then, A Molnar, HG Xing, and D Jena.

Featured in EE World Online, Industrial News

The first p-channel nitride transistors that break the GHz speed barrier are demonstrated. By leveraging the unique single-channel high-density polarization-induced 2D hole gas of the GaN/AlN heterostructure, best-in-class contact resistances, and scaled T-gate design, p-channel transistor on-currents of 428 mA/mm are observed, with cutoff frequencies in the 20 GHz regime. These observations demonstrate the unique enabling role of the polarization discontinuity at the GaN/AlN semiconductor heterojunction and offer significant hope for a new high-speed and high-voltage wide-bandgap CMOS device platform for applications in RF and power electronics domains.

P17. Electric Fields and Surface Fermi Level in Undoped GaN/AlN Two-Dimensional Hole Gas Heterostructures

physica status solidi rrl (2021)

Łukasz Janicki*, Reet Chaudhuri*, Samuel James Bader, Huili Grace Xing, Debdeep Jena, Robert Kudrawiec

*co-first author

III-nitride heterostructures have a high built-in electric field due to the intrinsic polarization. Contactless electro-reflectance (CER) spectroscopy is used to porbe and measure the built-in electric field in GaN/AlN 2DHG heterostructures. Comparing to electrostatic simulations, a surface barrier height of ≈1.9 eV for holes is proposed in these technologically relevant heterostructures.

P16. Molecular Beam Epitaxy Growth of Large-Area GaN/AlN 2D Hole Gas Heterostructures

physica status solidi (b) (2020)

Reet Chaudhuri, S. Bader, Z. Chen, D. Muller, H. Xing , D. Jena

A study of the growth conditions during molecular beam epitaxy (MBE) growth of metal‐polar GaN/AlN heterostructures is presented for optimal transport of the polarization‐induced 2D hole gases (2DHGs), along with the demonstration of large‐area growths of the 2DHGs on 2 in. wafers using optimized growth conditions.

P15. Prospects for wide bandgap and ultrawide bandgap CMOS devices.

IEEE Transactions on Electron Devices (2020)

Samuel James Bader, Hyunjea Lee, Reet Chaudhuri, Shimin Huang, Austin Hickman, Alyosha Molnar, Huili Grace Xing, Debdeep Jena, Han Wui Then, Nadim Chowdhury, et al.

P14. First RF Power Operation of AlN/GaN/AlN HEMTs with >3 A/mm and 3 W/mm at 10 GHz.

IEEE Journal of the Electron Devices Society (2021)

Austin Hickman, Reet Chaudhuri, Kazuki Nomoto, Lei Li, James CM Hwang, Huili Grace Xing, and Debdeep Jena.

P13. Large Signal Response of AlN/GaN/AlN HEMTs at 30 GHz.

Device Research Conference (DRC) (2021)

Austin Hickman, Reet Chaudhuri, Neil Moser, Micheal Elliot, Kazuki Nomoto, Lei Li, James CM Hwang, Huili Grace Xing, and Debdeep Jena.

P12. Polarization induced 2D hole gases in pseudomorphic undoped GaN/AlN heterostructures on single-crystal AlN substrates.

Applied Physics Letters (2021)

Zexuan Zhang, Jimy Encomendero, Reet Chaudhuri, Yongjin Cho, Vladamir Protasenko, Kazuki Nomoto, Kevin Lee, Masato Toita, Huili Grace Xing, and Debdeep Jena.

P11. Quantitative scanning microwave microscopy of 2D electron and hole gases in AlN/GaN heterostructures.

Applied Physics Letters (2022)

Xiaopeng Wang, Gianluca Fabi, Reet Chaudhuri, Austin Hickman, Mohammad Javad Asadi, Kazuki Nomoto, Huili Grace Xing, Debdeep Jena, Marco Farina, and James C. M. Hwang

P10. Next generation electronics on the ultrawide-bandgap aluminum nitride platform

Semicond. Sci. Technol. 36 (2021)

Austin Lee Hickman, Reet Chaudhuri, Samuel James Bader, Kazuki Nomoto, Lei Li, James Hwang, Huili Grace Xing, and Debdeep Jena.

P9. High-Mobility Two-Dimentional Electron Gases at Al xGa 1−xN/GaN Heterostructures Grown by PA-MBE

Bulletin of the American Physical Society ( 2020 )

Y. Ren, Y. Cho, A.Hickman, Reet Chaudhuri, P. Dang , M Lee, W. Zhao, H. Xing , D. Jena

P8. GaN/AlN Schottky-gate p-channel HFETs with InGaN contacts and 100 mA/mm on-current

IEEE International Electron Devices Meeting ( IEDM ) (2019)

S. Bader, Reet Chaudhuri, A. Hickman, K. Nomoto, S. Bharadwaj , H.W. Then, H. Xin g , D. Jena

P7. Molecular beam epitaxial growth of scandium nitride on hexagonal SiC, GaN, and AlN

Applied Physics Letters (2019)

J Casamento, J. Wright, Reet Chaudhuri, H. Xing , D. Jena

P6. GaN-Based FETs with Laterally-Gated Multi-2DEG Channels for High Power and Linearity

ECS Transactions (2019)

K. Shinohara, C. King , E. Regan, J. Bergman, A. Carter, A. Arias, M. Urteaga, B. Brar, R. Page, Reet Chaudhuri, SM Islam, H. Xing , D. Jena

P5. Wurtzite phonons and the mobility of a GaN/AlN 2D hole gas

Appl. Phys. Lett. 114, 253501 (2019)

S.J. Bader, R. Chaudhuri, M. Schubert, H. Then, H. Xing, D. Jena

P3. High Breakdown Voltage in RF AlN/GaN/AlN Quantum Well HEMTs

IEEE Electron Device Letters (2018)

A. Hickman, R. Chaudhuri, S.J. Bade, K. Nomoto, K. Lee, H. Xing, D. Jena

P3. GaN-based multi-channel transistors with lateral gate for linear and efficient millimeter-wave power amplifiers

IEEE MTT-S International Microwave S y m p osium ( IMS ), (2019)

K. Shinohara, C. King , E. Regan, J. Bergman, A. Carter, A. Arias, M. Urteaga, B. Brar, R. Page, Reet Chaudhuri, SM Islam, H. Xing , D. Jena

P2. Gate-recessed E-mode p-channel HFET with high on-current based on GaN/AlN 2D hole gas

IEEE Electron Device Letters, vol. 39, no. 12 (2018)

S.J. Bader, R. Chaudhuri, K. Nomoto, A. Hickman, H. Then, Z. Chen, D. Muller, H. Xing, D. Jena

P1. Terahertz spectroscopy of an electron-hole bilayer system in AlN/GaN/AlN

Appl. Phys. Lett. 111, 073102 (2017)

H. Condori Quispe, S. M. Islam, S.J. Bader, A. Chanana, K. Lee, R. Chaudhuri, A. Nahata, H. Xing, D. Jena and B. Sensale-Rodriguez