Electrical Characterization of High-k (k>115) Crystalline SrTiO3 (STO) thin film integration with GaN with Nanomembrane Transfer Process

TL;DR

This study demonstrates the successful transfer and electrical characterization of high-k crystalline SrTiO3 thin films on GaN, revealing high dielectric constants, low leakage currents, and effects of annealing on properties for power device applications.

Contribution

It introduces a nanomembrane transfer process for high-k SrTiO3 films onto GaN and provides detailed electrical property analysis, including effects of thermal annealing.

Findings

Leakage current was negligible up to 6-11 V.

Dielectric constant ranged from 50 to 186 depending on thickness.

Annealing improved dielectric constant but reduced leakage performance.

Abstract

High-k (115), crystalline SrTiO3 (STO) thin film was transferred on GaN for potential applications in power devices (transistor and diodes) by nanomembrane transfer method and the detailed electrical properties such as leakage current, CV profiles, dielectric constant, frequency dispersion was reported from fabricated MOSCAP structures. The leakage current was negligible (under noise-level of tool) up to 6 V and 11 V for 50 nm and 200 nm STO membrane respectively A high-quality dielectric was indicated by the CV profile, which showed almost negligible frequency dispersion in the frequency range of 10 kHz to 500 kHz. The dielectric constant was 50 to 82 with the 50 nm thick STO membrane and 115 to 186 in the 200 nm thick STO membrane. Thermal annealing of the membrane in ambient conditions at 250 degrees for 2 hours led to a slight improvement in the dielectric constant (8 to 20 percent), albeit at the expense of degraded leakage current performance, as indicated by a reduction of 1 V to 3 V in the "no leakage region" of the IV curves after annealing. The possible physical mechanisms responsible for these changes were also analyzed and discussed.