Low Temperature Homoepitaxy Of (010) $\beta$-Ga$_2$O$_3$ By Metalorganic Vapor Phase Epitaxy : Expanding The Growth Window

TL;DR

This study demonstrates high-quality, low-temperature homoepitaxial growth of $eta$-Ga$_2$O$_3$ thin films with high mobility and controllable doping, expanding the growth temperature window for this material.

Contribution

It introduces a low-temperature growth process for $eta$-Ga$_2$O$_3$ homoepitaxy that achieves high crystalline quality and improved doping profiles, previously limited to higher temperatures.

Findings

Achieved room temperature Hall mobility of 186 cm$^2$/Vs.

Demonstrated controllable Si doping from 2×10$^{16}$ to 2×10$^{19}$ cm$^{-3}$.

Established an abrupt doping profile with a decay of ~5 nm/dec, ten times better than at higher temperatures.

Abstract

In this work, we report on the growth of high-mobility $\beta$-Ga$_2$O$_3$ homoepitaxial thin films grown at a temperature much lower than the conventional growth temperature window for metalorganic vapor phase epitaxy. Low-temperature $\beta$-Ga$_2$O$_3$ thin films grown at 600$^{\circ}$C on Fe-doped (010) bulk substrates exhibits remarkable crystalline quality which is evident from the measured room temperature Hall mobility of 186 cm$^2$/Vs for the unintentionally doped films. N-type doping is achieved by using Si as a dopant and controllable doping in the range of 2$\times$10$^{16}$ - 2$\times$10$^{19}$ cm$^{-3}$ is studied. Si incorporation and activation is studied by comparing silicon concentration from secondary ion mass spectroscopy (SIMS) and electron concentration from temperature-dependent Hall measurements. The films exhibit high purity (low C and H concentrations) with a very low concentration of compensating acceptors (2$\times$10$^{15}$ cm$^{-3}$) even at this growth temperature. Additionally, abrupt doping profile with forward decay of $\sim$ 5nm/dec (10 times improvement compared to what is observed for thin films grown at 810$^{\circ}$C) is demonstrated by growing at a lower temperature.