Homoepitaxial Growth of Gan Thin Film Using Radical Assist Sputter Epitaxy Method at Low Temperature

Abstract

We investigated unintentionally doped-gallium nitride (GaN) thin films grown on GaN template substrates at a substrate temperature of 600 °C using our developed radical assist sputter epitaxy (RaSE) method. To achieve GaN thin films with minimal defects and a smooth surface at low temperatures, it was necessary to utilize a slightly higher Ga supply compared to that in the intermediate conditions. However, the process margin for obtaining droplet-free, high-quality films using the RaSE method was notably narrow due to the formation of Ga droplets in Ga-rich conditions. These findings highlight the need to expand the process margins for effective film growth. Additionally, a significant amount of O impurities was incorporated into the GaN thin films produced by the RaSE method, a specific challenge associated with low-temperature growth. Nonetheless, these impurities could be advantageous for fabricating n-type GaN thin films and may also be useful in creating contact layers for GaN devices that require high doping concentrations but cannot withstand high temperatures.

Keywords: Semiconductor, Gallium nitrides, Epitaxial growth, Sputtering, Radical assist sputter epitaxy