A Novel Analysis of ${L}_{\text{gd}}$ Dependent-1/ ${f}$ Noise in In0.08Al0.92N/GaN

In
_0.08
Al
_0.92
N/GaN fin-type high-electron mobility transistors (fin-HEMTs) with different gate-to-drain lengths (
${L} _{\text {gd}}$
) are fabricated and characterized by dc and low-frequency noise (LFN) measurements. The fabricated device with the largest
${L} _{\text {gd}}$
exhibits the degradation of the maximum drain current and transconductance with a positive shift of the threshold voltage. LFN measurements of the In
_0.08
Al
_0.92
N/GaN fin-HEMTs reveal clear 1/
${f}$
behavior of the noise spectra, and the minimum value is observed in the device at
${L} _{\text {gd}} = {20}\,\,\mu \text{m}$
. The devices with smaller
${L} _{\text {gd}}$
follow a carrier number fluctuation noise model owing to electron trapping/detrapping into the In
_0.08
Al
_0.92
N barrier layer from the 2-D electron gas (2DEG) channel. In contrast, the device with the largest
${L} _{\text {gd}}$
shows correlated mobility fluctuations due to the large 2DEG mobility fluctuations in the large access area.