Demonstration of Quasi-AlGaN/GaN HFET Using Ultrathin GaN/AlN Superlattices as a Barrier Layer

• Published in: IEEE electron device letters 2010-09, Vol.31 (9), p.945-947
• Main Authors: Yagi, Shuichi, Xu-Qiang Shen, Kawakami, Yusuke, Ide, Toshihide, Shimizu, Mitsuaki
• Format: Article
• Language: English
• Subjects: Aluminum nitride; Applied sciences; Barrier layers; Channels; Compound structure devices; Current collapse; Current density; Devices; Direct current; Electronics; Energy loss; Exact sciences and technology; Gallium nitride; Gallium nitrides; HEMTs; heterostructure field-effect transistor (HFET); Heterostructures; Laser sintering; MODFETs; Passivation; quasi-AlGaN/GaN; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; sheet resistance; Stress; Superlattices; Testing; Transistors
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2010.2052778

We demonstrate a quasi-AlGaN/GaN heterostructure field-effect transistor (HFET). A quasi-AlGaN barrier layer consists of ultrathin GaN/AlN superlattices (SLs), resulting in low sheet resistance in the heterostructures. The dc characteristics show a large maximum drain current density (I dmax = 830 mA/mm) and low on-resistance (R on = 4.3 Ω·mm) with a source-drain separation of 12 μm. The I d reduction is less than 3% after the dc bias stress test, indicating that the current collapse is greatly suppressed in our device even without a passivation film deposited on the channel surface. GaN/AlN SLs are considered to obstruct the transmission of carriers toward surface traps, thus the suppression of the current collapse. The quasi-AlGaN/GaN HFET will be useful for high-frequency high-power high-speed switching applications with low energy loss.