Impact of chamber pressure and Si-doping on the surface morphology and electrical properties of homoepitaxial (100) beta-Ga2O3 thin films grown by MOVPE

摘要

The influence of chamber pressure and Si-doping on the growth rate, surface morphology and Hall mobility was investigated for beta-Ga2O3 thin films homoepitaxially grown by metalorganic vapor phase epitaxy on Mg-doped beta-Ga2O3 (100) substrates with 4 degrees miscut. Transitions from step-bunching to step-flow to 2D island growth modes were achieved by varying the chamber pressure from 10 mbar to 40 mbar and/or by varying the O-2/Ga ratio. High-quality beta-Ga2O3 homoepitaxial thin films with a high electron mobility of 153 cm(2) Vs(-1) have been obtained at a chamber pressure of 25 mbar and a growth rate of 3.6 nm min(-1). The Si-doped films show electron concentrations in the range of 1 x 10(17) to 2 x 10(19) cm(-3). When increasing the chamber pressure to 40 mbar step-flow growth mode and high charge carrier mobility can only be preserved by adjusting the O-2/Ga ratio and increasing the Ar push gas flow. Secondary ion mass spectrometry and Hall measurements for Si and electron concentration, respectively, revealed Si compensation at higher tetraethyl orthosilicate flux.