Sputter epitaxy of ScAlN films on GaN high electron mobility transistor structures

Abstract

ScAlN has emerged as a promising material for GaN-based high electron mobility transistors (HEMTs) due to its unique piezoelectric and ferroelectric properties, which can significantly enhance electronic performance. This study investigated the epitaxial growth of ScAlN films on AlGaN/GaN HEMT structures using a sputtering method, focusing on the structural and electrical characteristics of the heterostructures. ScAlN films with varying Sc compositions (5%–20%) were grown on AlGaN/AlN/GaN/SiC template substrates. High-resolution x-ray diffraction and reciprocal space mapping revealed the coherent growth of ScAlN, and the increase in the c-axis lattice constant increases with Sc composition. Hall effect measurements of the Sc0.06Al0.94N/AlGaN/AlN/GaN HEMT structures showed an increase in sheet carrier density compared to structures prior to the growth of ScAlN, highlighting its potential for improved electrical performance. These findings underscore the value of ScAlN as a barrier layer material of GaN HEMTs, enhancing device efficiency and output power.