Ultra-wide bandgap p-type α-(Ir,Ga)2O3 films with bandgaps of up to 4.3 eV have been obtained by unintentional doping or Mg doping. For Mg-doped films, Hall-effect measurements revealed a hole concentration of 9.9 × 1018 to 8.1 × 1019 cm−3 and a mobility of 0.13 − 0.92 cm2/V s, respectively. A preliminary test of a pn junction diode composed of p-type α-(Ir,Ga)2O3 and n-type α-Ga2O3 did not show catastrophic breakdown in the reverse direction until 100 V and the current on/off ratio at +3 V/−3V was 5 × 105. Since α-(Ir,Ga)2O3 and α-Ga2O3 take the same crystal structure and are well lattice-matched (with a lattice mismatch of <0.3%), the formation of a high-quality pn heterojunction is encouraged; this is one of the advantages of the corundum material system.

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