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Control of the conductivity of Si-doped β-Ga2O3 thin films via growth temperature and pressure



Si-doped β-Ga2O3 thin films were grown at temperatures between 400 and 650 °C and oxygen partial pressures ranging from 3 × 10−4 mbar to 2.4 × 10−2 mbar prepared by pulsed laser deposition (PLD) on c-plane sapphire substrates. For high oxygen partial pressure the samples are composed of multiple crystalline phases; for decreasing oxygen partial pressure the crystallinity improves and single phase (inline image)-oriented thin films are obtained for an oxygen partial pressure below inline image at a growth temperature of 650 °C. We find a correlation between surface morphology of our thin films and their conductivity; an increasing root mean square surface roughness entails increased conductivity. Further we show that the oxygen partial pressure resulting in maximal conductivity decreases with increasing growth temperature. The results provide means to realize β-Ga2O3-based devices such as rectifiers, photodetectors or thin film transistors with optimized surface roughness, structural quality, and conductivity.

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