Plasma-assisted molecular beam epitaxy and characterization of SnO2 (101) on r-plane sapphire

Plasma-assisted molecular beam epitaxy has been shown to be a viable and practical method for producing high quality tin oxide, SnO2. Phase-pure epitaxial single crystalline SnO2 (101) thin films of 1μm in thickness were reproducibly grown on r-plane sapphire Al2O3 (101¯2) substrates. The SnO2 epitaxy progressed in the Volmer–Weber growth mode. A minimum on-axis ω-scan full width at half maximum of 0.22° for the SnO2 (101) peak was measured indicating relatively low film mosaic. An epitaxial relationship of [010]SnO2∥[1¯21¯0]sapphire and [1¯01]SnO2∥[1¯011]sapphire was determined between the film and substrate. A SnO2 film tilt of 1.3° around the [010]SnO2 toward [0001]sapphire was measured. A dislocation density of 8×109cm−2 was measured. Hall effect measurements quantified an unintentionally doped electron concentration for different samples in a range (0.3–3.0)×1017cm−3 with a corresponding electron mobility range of 20–100cm2∕Vs. The SnO2 growth behavior was determined to be in one of the two distinct ...