DC Characteristics and Low-Frquency Noise of AlGaN/GaN HEMTs with Different Gate-to-Source Lengths

In this paper, DC and low-frequency noise characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) with different gate-to-source lengths (L
GS
) are presented. Due to the different (L
GS
), the device with shortest shows highest transconductance (g
m
) and drain current. But the threshold voltages (V
TH
) are the same for all devices. In low-frequency noise measurement, not only flicker noise (1/f noise) exists also accompany by generation-recombination noise (G-R) noise). Noise power spectral densities (PSD) are similar in devices with different L
GS
, and 1/f noise shows carrier number fluctuation (CNF) is the dominant cause. In addition, this paper discussed the G-R noise and extracted the traps in GaN buffer layer with activation energy of $\sim 0.35 \text{eV}$.