Optimization of AlGaN/GaN HEMTs for high frequency operation

✍ Scribed by Palacios, T. ;Dora, Y. ;Chakraborty, A. ;Sanabria, C. ;Keller, S. ;DenBaars, S. P. ;Mishra, U. K.

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 233 KB
• Volume: 203
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200565384

✦ Synopsis

Abstract

In this paper, the structure and processing of AlGaN/GaN high electron mobility transistors have been optimized for maximum small signal gain at high frequencies. The effect of the gate resistance, gate‐to‐drain capacitance and output conductance on the power gain cut‐off frequency, f ~max~, of the devices has been experimentally studied. The reduction of the gate width allowed a 4‐fold decrease in gate resistance which resulted in almost a 100% increase in f ~max~. To minimize C ~gd~, Γ‐shape gates have been processed instead of the conventional T‐shape submicron gates. Finally, to reduce the output conductance, the confinement of the 2‐dimensional electron gas was increased by using an ultra‐thin InGaN layer below the GaN channel. This InGaN back‐barrier caused a 2‐fold improvement in output conductance which allowed a 20% increase in f ~max~. By optimizing all these parameters, AlGaN/GaN transistors with a record f ~max~ of 230 GHz were obtained. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)