Step flow growth of β-Ga2O3 thin films on vicinal (100) β-Ga2O3 substrates grown by MOVPE

Abstract

Homoepitaxial (100) β-Ga2O3 films were grown on substrates with miscut angles of 2°, 4°, and 6° toward [001¯] by metal organic vapor phase epitaxy. Step-flow growth mode, resulting in smooth film surfaces and high crystalline quality, could only be achieved if the diffusion length on the film surface corresponds approximately to the width of the terraces. Otherwise, 2D islands or step-bunching is obtained, which results in a deteriorated crystalline quality and reduced Hall mobility of the electrons. By varying the growth parameters such as the O2/Ga ratio, Ar push gas flow, and chamber pressure, the diffusion length could be adjusted so that step-flow growth mode could be achieved at all miscut angles. Furthermore, the growth rate could remarkably be increased from 1.6 nm/min to 4.3 nm/min. For homoepitaxial β-Ga2O3 films grown in step-flow growth mode, TEM measurements revealed a high crystalline quality, which is correlated with a high Hall mobility of 131 cm2/V s at a carrier concentration of 1.6 × 1017cm−3, which is comparable with β-Ga2O3 single crystal bulk values. This study clearly points out the high potential of β-Ga2O3 films for high performance MOSFETs if the influence of the deposition parameters on the structural and electrical properties is well understood.