Copyright © 2006 The Institute of Electronics, Information and Communication Engineers
Special Section on Heterostructure Microelectronics with TWHM2005 -- Papers -- GaN-Based Devices |
Review of Recent Developments in Growth of AlGaN/GaN High-Electron Mobility Transistors on 4H-SiC by Plasma-Assisted Molecular Beam Epitaxy
1 The authors are with Materials Department, University of California, Santa Barbara CA 93106, USA. E-mail: acorrion{at}engineering.ucsb.edu, 2 The authors are with Electrical and Computer Engineering Department, University of California, Santa Barbara CA 93106, USA.
In this paper we review our recent work developing the growth of AlGaN/GaN high-electron mobility transistors (HEMTs) grown on SiC (0001) by plasma-assisted molecular beam epitaxy (PA-MBE). State-of-the-art AlGaN/GaN HEMTs have been achieved using MBE-grown material. Buffer leakage was an important limiting factor for early devices. We have shown that by appropriately controlling the Al/N flux ratio during growth of the nucleation layer on SiC(0001), low-leakage GaN buffers can be subsequently grown. In addition, a "modulated growth" technique was developed to achieve large area uniformity and surface morphology control. High-performance HEMTs were fabricated utilizing these two techniques. On 200 nm gate-length devices, at 4 GHz an output power density of 8.4 W/mm was obtained with a power-added efficiency (PAE) of 67% at a drain bias of 30 V. At a higher drain bias (42 V), 13.7 W/mm with a PAE of 55% was achieved.
Key Words: MBE, Gallium Nitride, HEMT, microwave, MBE
Manuscript received November 8, 2005.