Jump to main content
Jump to site search


Design principle for a p-type oxide gate layer on AlGaN/GaN toward normally-off HEMTs: Li-doped NiO as a model

Author affiliations

Abstract

Integration of the p-type oxide gate layer on AlGaN/GaN is a promising approach to explore normally-off high electron mobility transistors (HEMTs). However, the critical reason for the ultralow threshold voltage in intrinsic p-type oxide gated HEMTs remains elusive. Herein, Li-doped NiO thin films with various doping contents were grown on AlGaN/GaN/Si substrates by pulsed laser deposition (PLD) to identify the most important physical properties and design principle of p-type oxide for normally-off HEMTs. With the increasing Li doping content up to 25%, Ni0.75Li0.25O on AlGaN/GaN exhibits excellent epitaxial growth quality with good interfacial state, a wide band gap of 3.65 eV and an ultrahigh hole concentration of 6.81 × 1019 cm−3. Nevertheless, the Ni0.75Li0.25O/AlGaN/GaN/Si heterostructure still suffers from a low threshold voltage of merely −2.12 V. By resolving the band alignment at the Ni0.75Li0.25O/AlGaN interface and the depletion mechanism for p-type Ni0.75Li0.25O on 2DEG, the band alignment matching is ascribed to be the most critical issue for intrinsic p-type oxide gated normally-off HEMTs with a low threshold voltage, that is, a relatively small energy level difference value between the conduction band of GaN and the valence band of intrinsic p-type oxide. Based on the results, the design principle of the p-type oxide gate layer on AlGaN/GaN for normally-off HEMTs is proposed, and p-type oxides doped from intrinsic n-type oxides are suspected to be competitive candidates.

Graphical abstract: Design principle for a p-type oxide gate layer on AlGaN/GaN toward normally-off HEMTs: Li-doped NiO as a model

Back to tab navigation

Supplementary files

Article information


Submitted
12 Aug 2019
Accepted
03 Dec 2019
First published
06 Dec 2019

J. Mater. Chem. C, 2020, Advance Article
Article type
Paper

Design principle for a p-type oxide gate layer on AlGaN/GaN toward normally-off HEMTs: Li-doped NiO as a model

G. Li, X. Li, J. Zhao, F. Yan, Q. Zhu and X. Gao, J. Mater. Chem. C, 2020, Advance Article , DOI: 10.1039/C9TC04467A

Social activity

Search articles by author

Spotlight

Advertisements