A Novel Analysis of ${L}_{\text{gd}}$ Dependent-1/ ${f}$ Noise in In 0.08 Al 0.92 N/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.