Formation of indium–tin oxide ohmic contacts for β-Ga₂O₃

Abstract

Abstract Sputter-deposited indium–tin oxide (ITO) electrodes became ohmic contacts for unintentionally doped β-Ga 2 O 3 (010) substrates with a carrier concentration of 2 × 10 17 cm −3 after rapid thermal annealing in a wide range of annealing temperatures of 900–1150 °C. The formation of an ohmic contact is attributed to interdiffusion between ITO and β-Ga 2 O 3 , as evidenced by the results of transmission electron microscopy and energy-dispersive X-ray spectroscopy. The interdiffusion decreases the band gap and increases the donor concentration of β-Ga 2 O 3 at the interface, and forms an intermediate semiconductor layer desirable for carrier transport. The ITO ohmic contact is particularly useful for future β-Ga 2 O 3 devices operated at high temperatures.