Rohith Soman

All Publications

• Negative capacitance overcomes Schottky-gate limits in GaN high-electron-mobility transistors. Science (New York, N.Y.) Khan, A. I., Kim, J. K., Sikder, U., Das, K., Rodriguez, T., Soman, R., Chowdhury, S., Salahuddin, S. 2025: eadx6955

  Abstract

  For high-electron-mobility transistors based on two-dimensional electron gas (2DEG) within a quantum well, such as those based on AlGaN/GaN heterostructure, a Schottky-gate is used to maximize the amount of charge that can be induced and thereby the current that can be achieved. However, the Schottky-gate also leads to very high leakage current through the gate electrode. Adding a conventional dielectric layer between the nitride layers and gate metal can reduce leakage; but this comes at the price of a reduced drain current. Here, we used a ferroic HfO2- ZrO2 bilayer as the gate dielectric and achieved a simultaneous increase in the ON current and decrease in the leakage current, a combination otherwise not attainable with conventional dielectrics. This approach surpasses the conventional limits of Schottky GaN transistors and provides a new pathway to improve performance in transistors based on 2DEG.

  View details for DOI 10.1126/science.adx6955

  View details for PubMedID 40638712

• Integration of top-side low-temperature diamond on AlGaN/GaN RF HEMT for device-level cooling APPLIED PHYSICS LETTERS Soman, R., Malakoutian, M., Woo, K., Kim, J., Rodriguez, T., Martinez, R., DeJarld, M., Tahhan, M., Valliancourt, J., Chumbes, E. M., Laroche, J., Chowdhury, S. 2025; 126 (21)

  View details for DOI 10.1063/5.0261673

  View details for Web of Science ID 001497981100014

• Integration of 150 nm gate length N-polar GaN MIS-HEMT devices with all-around diamond for device-level cooling APPLIED PHYSICS EXPRESS Soman, R., Malakoutian, M., Kim, J., Akso, E., Hatui, N., Wurm, C., Mishra, U., Chowdhury, S. 2025; 18 (4)

  View details for DOI 10.35848/1882-0786/adcb87

  View details for Web of Science ID 001475872300001

• Lossless Phonon Transition Through GaN-Diamond and Si-Diamond Interfaces ADVANCED ELECTRONIC MATERIALS Malakoutian, M., Woo, K., Rich, D., Mandia, R., Zheng, X., Kasperovich, A., Saraswat, D., Soman, R., Jo, Y., Pfeifer, T., Hwang, T., Aller, H., Kim, J., Lyu, J., Mabrey, J., Rodriguez, T., Pomeroy, J., Hopkins, P. E., Graham, S., Smith, D. J., Mitra, S., Cho, K., Kuball, M., Chowdhury, S. 2024

  View details for DOI 10.1002/aelm.202400146

  View details for Web of Science ID 001265392700001

• Cooling future system-on-chips with diamond inter-tiers CELL REPORTS PHYSICAL SCIENCE Malakoutian, M., Kasperovich, A., Rich, D., Woo, K., Perez, C., Soman, R., Saraswat, D., Kim, J., Noshin, M., Chen, M., Vaziri, S., Bao, X., Shih, C., Woon, W., Asheghi, M., Goodson, K. E., Liao, S., Mitra, S., Chowdhury, S. 2023; 4 (12)

  View details for DOI 10.1016/j.xcrp.2023.101686

  View details for Web of Science ID 001144107300001

• Development of 300-400 °C grown diamond for semiconductor devices thermal management MRS ADVANCES Malakoutian, M., Soman, R., Woo, K., Chowdhury, S. 2023

  View details for DOI 10.1557/s43580-023-00677-0

  View details for Web of Science ID 001103119100001

• Growth and mobility characterization of N-polar AlGaN channel high electron mobility transistors APPLIED PHYSICS LETTERS Noshin, M., Wen, X., Soman, R., Xu, X., Chowdhury, S. 2023; 123 (6)

  View details for DOI 10.1063/5.0140777

  View details for Web of Science ID 001044510200007

• Demonstration of N-Polar All-AlGaN High Electron Mobility Transistors With 375 mA/mm Drive Current IEEE ELECTRON DEVICE LETTERS Noshin, M., Soman, R., Chowdhury, S. 2023; 44 (7): 1072-1075

  View details for DOI 10.1109/LED.2023.3279400

  View details for Web of Science ID 001021302800011

• Scaling Study on High-Current Density Low-Dispersion GaN Vertical FinFETs IEEE ELECTRON DEVICE LETTERS Jeong, S., Lee, K., Chun, J., Soman, R., Chowdhury, S. 2023; 44 (5): 841-844

  View details for DOI 10.1109/LED.2023.3259002

  View details for Web of Science ID 000980442400035

• Impact of Diamond Passivation on f(T) and f(max) of mm-wave N-Polar GaN HEMTs IEEE TRANSACTIONS ON ELECTRON DEVICES Zhou, X., Malakoutian, M., Soman, R., Bian, Z., Martinez, R., Chowdhury, S. 2022

  View details for DOI 10.1109/TED.2022.3218612

  View details for Web of Science ID 000886832400001

• Low Thermal Budget Growth of Near-Isotropic Diamond Grains for Heat Spreading in Semiconductor Devices ADVANCED FUNCTIONAL MATERIALS Malakoutian, M., Zheng, X., Woo, K., Soman, R., Kasperovich, A., Pomeroy, J., Kuball, M., Chowdhury, S. 2022

  View details for DOI 10.1002/adfm.202208997

  View details for Web of Science ID 000854896500001

• Nanoporous GaN on p-type GaN: A Mg out-diffusion compensation layer for heavily Mg-doped p-type GaN. Nanotechnology Lee, K. J., Nakazato, Y., Chun, J., Wen, X., Meng, C., Soman, R., Noshin, M., Chowdhury, S. 2022

  Abstract

  Embeddingp-type gallium nitride (p-GaN) with controlled Mg out-diffusion in adjacent epitaxial layers is a key for designing various multi-junction structures with high precision and enabling more reliable bandgap engineering of III-nitride-based optoelectronics and electronics. Here, we report, for the first time, with experimental evidence how nanoporous GaN (NP GaN) can be introduced as a compensation layer for the Mg out-diffusion fromp-GaN. NP GaN onp-GaN provides an ex-situ-formed interface with oxygen and carbon impurities, compensating Mg out-diffusion fromp-GaN. To corroborate our findings, we used two-dimensional electron gas (2DEG) formed at the interface of AlGaN/GaN as the indicator to study the impact of the Mg out-diffusion from underlying layers. Electron concentration evaluated from the capacitance-voltage measurement shows that 9 * 1012cm-2of carriers accumulate in the AlGaN/GaN 2DEG structure grown on NP GaN, which is the almost same number of carriers as that grown with nop-GaN. In contrast, 2DEG onp-GaN without NP GaN presents 9 * 109cm-2of the electron concentration, implying 2DEG structure is depleted by Mg out-diffusion. The results address the efficacy of NP GaN and its' role in successfully embeddingp-GaN in multi-junction structures for various state-of-the-art III-nitride-based devices.

  View details for DOI 10.1088/1361-6528/ac91d7

  View details for PubMedID 36103775

• Vertical Ga2O3 MOSFET With Magnesium Diffused Current Blocking Layer IEEE ELECTRON DEVICE LETTERS Zeng, K., Soman, R., Bian, Z., Jeong, S., Chowdhury, S. 2022; 43 (9): 1527-1530

  View details for DOI 10.1109/LED.2022.3196035

  View details for Web of Science ID 000845067200038

• A study on MOCVD growth window for high quality N-polar GaN for vertical device applications SEMICONDUCTOR SCIENCE AND TECHNOLOGY Soman, R., Noshin, M., Chowdhury, S. 2022; 37 (9)

  View details for DOI 10.1088/1361-6641/ac7e67

  View details for Web of Science ID 000829564000001

• A systematic study of the regrown interface impurities in unintentionally doped Ga-polar c-plane GaN and methods to reduce the same SEMICONDUCTOR SCIENCE AND TECHNOLOGY Noshin, M., Soman, R., Xu, X., Chowdhury, S. 2022; 37 (7)

  View details for DOI 10.1088/1361-6641/ac71bf

  View details for Web of Science ID 000807760500001