Al2O3-Dielectric In0.18Al0.82N/AlN/GaN/Si Metal-Oxide-Semiconductor Heterostructure Field-Effect Transistors With Backside Substrate Metal-Trench Structure

Abstract

This paper investigates novel Al2O3-dielectric In0.18Al0.82N/AlN/GaN metal-oxide-semiconductor heterostructure field-effect transistors (MOS-HFETs) with backside metal-trench structure grown by using a non-vacuum ultrasonic spray pyrolysis deposition technique. 3- $\mu \text{m}$ deep metal trenches coated with 150-nm thick Ni were formed on the backside of the Si substrate to improve the heat dissipation efficiency. The present In0.18Al0.82N/AlN/GaN MOS-HFET (Schottky-gate HFET) has demonstrated improved maximum drain–source current density ( $I_{\mathrm{ DS, \max }}$ ) of 1.08 (0.86) A/mm at $\textit{V}_{\mathrm{ DS}}=$ 8 V, gate-voltage swing of 4 (2) V, on/off-current ratio ( $I_{\mathrm{ on}} /I_{\mathrm{ off}} $ ) of $8.9\times 10^{8}$ ( $7.4 \times 10^{4} $ ), subthreshold swing of 140 (244) mV/dec, two-terminal off-state gate-drain breakdown voltage (BVGD) of −191.1 (−173.8) V, turn-on voltage ( $V_{\mathrm{ on}} $ ) of 4.2 (1.2) V, and three-terminal on-state drain-source breakdown voltage (BV $_{DS}$ ) of 155.9 (98.5) V. Enhanced power performances, including saturated output power ( $\textit{P}_{out}$ ) of 27.9 (21.5) dBm, power gain ( $\textit{G}_{a}$ ) of 20.3 (15.5) dB, and power-added efficiency (PAE) of 44.3% (34.8%), are achieved.