Epitaxial growth of ε-(AlGa) 2 O 3 films on sapphire substrate by PLD and the fabrication of photodetectors

Abstract

The growth of single crystal ε-Ga2O3 films under the assistance of Sn element was studied using pulsed laser deposition (PLD). The crystal structure, optical properties and chemical state of the element were investigated to analyze the influence of tin during the film epitaxy. There is a transition layer at the substrate and the ε-Ga2O3 film interface. Increase in Sn atomic ratio will cause a rise in the transition layer thickness and the growth rate. In addition, due to the Sn atoms aggregation and the formation of clusters, the higher dark current (Idark), photocurrent (Iphoto) and responsivity (R) were achieved for the enhanced electron transportation in the ε-Ga2O3 metal-semiconductor-metal (MSM) photodetectors. The optical bandgap Eg determined from R increased from 4.81eV to 4.88eV and 4.94eV with Sn contents increasing from 0.9% to 1.2% and 1.5%, consistent with the transmittance results.