Investigation of Multiple-Mesa-Nanochannel Array GaN-Based MOSHEMTs with Al2O3 Gate Dielectric Layer

Abstract

In this work, an atomic layer deposition system was used to deposit Al2O3 high-k dielectric film as the gate insulator of GaN-based metal-oxide-semiconductor high-electron mobility transistors (MOSHEMTs). By using the Al2O3 gate dielectric layer, compared to planar channel structure, the direct current, high frequency, and flicker noise performances were improved in the GaN-based MOSHEMTs with fin-nanochannel array. For the GaN-based 80-nm-wide fin-nanochannel array MOSHEMTs, they exhibited superior performances of maximum extrinsic transconductance of 239 mS mm−1, threshold voltage of –0.4 V, unit gain cutoff frequency of 7.3 GHz, maximum oscillation frequency of 14.1 GHz, normalized noise power of 2.5 × 10−14 Hz−1, and Hooge’s coefficient of 1.4 × 10−6. The enhanced performances were attributed to the features of fin-nanochannel array of better gate control capability, enhanced pinch-off effect, and better heat dissipation driven by lateral heat flow within the space between fin-channels.