N-type doping of LPCVD-grown \b{eta}-Ga2O3 thin films using solid-source germanium

TL;DR

This study demonstrates controlled n-type doping of LPCVD-grown ta-Ga2O3 thin films with germanium, revealing how reactor design and growth conditions influence donor levels and carrier concentrations for high-power electronics.

Contribution

It introduces a method for Ge doping of ta-Ga2O3 films via LPCVD, analyzing how growth parameters affect impurity incorporation and donor energy levels.

Findings

Achieved Hall carrier concentrations from 10^17 to 10^19 cm^-3.

Germanium acts as a donor with energy levels between 8-10 meV at low growth rates.

Deeper donor levels (~85 meV) observed at higher growth rates.

Abstract

We report on the growth and characterization of Ge-doped \b{eta}-Ga2O3 thin films using a solid germanium source. \b{eta}-Ga2O3 thin films were grown using a low-pressure chemical vapor deposition (LPCVD) reactor with either an oxygen or gallium delivery tube. Films were grown on 6 degree offcut sapphire and (010) \b{eta}-Ga2O3 substrates with growth rates between 0.5 - 22 {\mu}m/hr. By controlling the germanium vapor pressure, a wide range of Hall carrier concentrations between 10^17 - 10^19 cm-3 were achieved. Low-temperature Hall data revealed a difference in donor incorporation depending on the reactor configuration. At low growth rates, germanium occupied a single donor energy level between 8 - 10 meV. At higher growth rates, germanium doping predominantly results in a deeper donor energy level at 85 meV. This work shows the effect of reactor design and growth regime on the kinetics of impurity incorporation. Studying donor incorporation in \b{eta}-Ga2O3 is important for the design of high-power electronic devices.