Manipulation of polarization effect to engineer III-nitride HEMTs for normally-off operation

Manipulation of polarization effect to engineer III-nitride HEMTs for normally-off operation

2014/12 Yung-Chi Yao, Chun-Ying Huang, Tai-Yuan Lin, Li-Lien Cheng, Ching-Yun Liu, Mei-Tan Wang, Jung-Min Hwang, Ya-Ju Lee

Abstract

We propose a novel, normally-off AlGaN/GaN high-electron-mobility transistor (HEMT) governed by polarization engineering. The fundamental concept is to grade the Al composition of the barrier layer from GaN to AlxGa1−xN, thereby alleviating the impact of piezoelectric polarization on the two-dimensional electron gas (2-DEG) and establishing a conduction-band profile well above the Fermi energy. These effects lead to a positive shift in the threshold voltage of the device and benefit the normally-off operation. It is observed that the device’s DC transfer characteristics can be further modulated simply by adjusting the Al composition of the AlyGa1−yN cap layer and the p-type doping concentration at the top of the GaN buffer layer. These findings, based on a physical simulation of the proposed device, provide a guideline for the implementation of highly efficient, normally-off AlGaN/GaN HEMTs.

•  Link:

http://www.sciencedirect.com/science/article/pii/S0167931714005152

• International Journals (國際期刊):

Yung-Chi Yao, Chun-Ying Huang, Tai-Yuan Lin, Li-Lien Cheng, Ching-Yun Liu, Mei-Tan Wang, Jung-Min Hwang, Ya-Ju Lee. Manipulation of polarization effect to engineer III-nitride HEMTs for normally-off operation,Microelectronic Engineering, Volume 138, 20 April 2015, Pages 1–6

• download:

https://drive.google.com/file/d/0B-Jg2ZDReoWubG1Fa0g0NUJXRjA/view?usp=sharing