Synthesis and characterization of β-Ga2O3 nanowires on amorphous substrates using radio-frequency powder sputtering

We investigated the growth mechanism and microstructure of β-Ga2O3 nanowires (NWs) deposited on amorphous SiN/Si(0 0 1), SiOx/Si(0 0 1), and glass substrates using radio-frequency powder sputtering. During growth, the β-Ga2O3 changed from an initial amorphous thin film into NWs. Since the deposition was performed in an Ar gas environment, the initial amorphous thin films were non-stoichiometric Ga oxide (Ga2O3−x). Oxygen-deficient deposition led to the formation of intermediate thin films by the phase separation of Ga2O3−x into metallic Ga clusters and stoichiometric β-Ga2O3. The Ga clusters acted as catalyst seeds in the growth of the β-Ga2O3 NWs through the self-catalytic vapor-liquid-solid mechanism. We found that the growth of β-Ga2O3 NWs is possible at temperatures greater than 450 °C, above which phase separation and Ga cluster formation occur. We also observed that NWs inherit the planar defects, such as twin boundaries, of the host Ga seed.