Corundum-Structured α-In 2 O 3 as a Wide-Bandgap Semiconductor for Electrical Devices

Corundum-structured α-In 2 O 3 was grown by mist chemical vapor deposition (CVD) on sapphire substrates with the use of α-Ga 2 O 3 buffer layers. The use of ozone (O 3 ) and thermal annealing in air were effective for improved surface morphology and electrical properties of the α-In 2 O 3 layer. MOSFETs were fabricated using the α-In 2 O 3 layer, where the residual electron concentrations were temporary reduced by doping Mg acceptors. Nevertheless the MOSFETs showed the best field-effect mobility of as high as 187 cm 2 /V⋅s and the best effective mobility of as high as 240 cm 2 /V⋅s, suggesting high potential of α-In 2 O 3 MOSFETs.