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

Homoepitaxial (100) beta -Ga2O3 films were grown on substrates with miscut angles of 2 degrees, 4 degrees, and 6 degrees toward [00 1 <mml:mo><overbar></mml:mover>] 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 O-2/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 1.6nm/min to 4.3nm/min. For homoepitaxial beta -Ga2O3 films grown in step-flow growth mode, TEM measurements revealed a high crystalline quality, which is correlated with a high Hall mobility of 131cm(2)/Vs at a carrier concentration of 1.6x10(17)cm(-3), which is comparable with beta -Ga2O3 single crystal bulk values. This study clearly points out the high potential of beta -Ga2O3 films for high performance MOSFETs if the influence of the deposition parameters on the structural and electrical properties is well understood.