Highly conductive homoepitaxial Si-doped Ga2O3 films on (010) β-Ga2O3 by pulsed laser deposition

Abstract

Si-doped Ga2O3 thin films were fabricated by pulsed laser deposition on semi-insulating (010) β-Ga2O3 and (0001) Al2O3 substrates. Films deposited on β-Ga2O3 showed single crystal, homoepitaxial growth as determined by high resolution transmission electron microscopy and x-ray diffraction. Corresponding films deposited on Al2O3 were mostly single phase, polycrystalline β-Ga2O3 with a preferred (201¯) orientation. An average conductivity of 732 S cm−1 with a mobility of 26.5 cm2 V−1 s−1 and a carrier concentration of 1.74 × 1020 cm−3 was achieved for films deposited at 550 °C on β-Ga2O3 substrates as determined by Hall-Effect measurements. Two orders of magnitude improvement in conductivity were measured using native substrates versus Al2O3. A high activation efficiency was obtained in the as-deposited condition. The high carrier concentration Ga2O3 thin films achieved by pulsed laser deposition enable application as a low resistance ohmic contact layer in β-Ga2O3 devices.