Gate-recess and device geometry impact on the microwave performance and noise properties of 0.1 mu m InAlAs/InGaAs HEMT's

Abstract

A study in which the deep recess was found to be essential in order to maintain a high gate aspect ratio and thus larger G/sub m/G/sub ds/ and C/sub gs//C/sub gd/ ratios is described. This ensures a high power gain and high f/sub max/ which is a figure of merit in microwave circuit operation. Also, proper recessed devices show less microwave noise and broader noise minima. The optimum recess for both microwave and noise performance was found to be around I/sub dss/ of 500 mA/mm for the HEMT and showed f/sub max/ of 217 GHz, f/sub T/ of 173 GHz, and a minimum noise figure of 0.6 dB. The device geometry effect was investigated, and the degradation of the device performance due to the parasitics was found for small gate width devices. Large gate width devices were limited in high frequency performance due to the high gate metal resistance. Overall, an appropriate recess, aspect ratio, and device periphery must be selected for optimum microwave performance. >