  This paper reports on the deposition of amorphous and crystalline thin films
of Ga2O3 by reactive pulsed direct current magnetron sputtering from a liquid
gallium target onto fused (f-) quartz and c plane (c-) sapphire substrates,
where the temperature of the substrate is varied from room temperature (RT) to
800{\deg}C. The deposition rate (up to 37 nm/min at RT on f-quartz and 5 nm/min
at 800{\deg}C on c-sapphire) is two to five times higher than the data given in
the literature for radio frequency sputtering. Deposited onto unheated
substrates, the films are X-ray amorphous. Well-defined X-ray diffraction peaks
of \b{eta}-Ga2O3 start to appear at a substrate temperature of 500{\deg}C.
Films grown on c-sapphire at temperatures above 600{\deg}C are epitaxial.
However, the high rocking curve full width at half maximum values of {\approx}
2.4-2.5{\deg} are indicative of the presence of defects. A dense and void-free
microstructure is observed in electron microscopy images. Composition analysis
show stoichiometry close to Ga2O3 and no traces of impurities. The optical
properties of low absorptance (<1%) in the visible range and an optical band
gap of approximately 5 eV are consistent with the data in the literature for
Ga2O3 films produced by other deposition methods.
