Transport Properties in GaN Metal‐Oxide‐Semiconductor Field‐Effect Transistor Almost Free of Interface Traps with AlSiO/AlN/p‐Type GaN Gate Stack

Abstract

The factors limiting channel mobility in AlSiO/p‐type GaN metal‐oxide‐semiconductor field‐effect transistors (MOSFETs) were examined by performing Hall‐effect measurements in conjunction with a gate bias, with and without a thin AlN interlayer. In the absence of this interlayer, the free carrier concentration associated with the Hall effect was significantly reduced compared with the net gate charge density estimated from capacitance–voltage data, indicating that electrons were trapped to a significant extent at the MOS interface. These interface traps were found to have an energy approximately 20 meV above the Fermi level in strong inversion based on temperature‐dependent Hall effect data. The insertion of a 0.8 nm thick AlN interlayer eliminated charge trapping such that almost all gate charges were mobile. The mobility components could be divided into types based on their effect on the effective electric field perpendicular to the channel. Coulomb scattering centers resulting from interface states were evidently reduced by inserting the AlN interlayer, which also enhanced the channel mobility to over 150 cm2/Vs.This article is protected by copyright. All rights reserved.