Design and Fabrication of GaN HEMT for Microwave Application

In this paper, a T-gate HEMT device was fabricated by using electron beam lithography technology. The DC test results of the GaN HEMT device showed that its maximum effective transconductance <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(g_{m:max})$</tex> was 170mS/mm, with a maximum channel current of 440 mA/mm. Frequency test results indicated a cutoff frequency <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(f_T)$</tex> of 33 GHz and a maximum oscillation frequency <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(f_{max})$</tex> of 67 GHz. Small-signal equivalent circuit modeling of the fabricated HEMT device was performed, along with the extraction of parasitic and intrinsic parameters. By characterizing the aforementioned parameters, it was confirmed that the fabricated GaN HEMT can be applied in the microwave field..