Investigation of metal-insulator-semiconductor diode with alpha-Ga2O3 insulating layer by liquid phase deposition

We report a metal-insulator-semiconductor (MIS) diode with an α-Ga 2 O 3 thin-film insulator layer grown by liquid-phase deposition (LPD). α-Ga 2 O 3 exhibits a high energy bandgap of 4.9–5.3 eV, which can effectively reduce the leakage current density and improve the breakdown voltage of the diode. The α-Ga 2 O 3 thin films are synthesized from GaOOH with LPD. The α-GaOOH crystal is simply obtained by the dissociation of the Ga(OH) 3 precursor solution. GaOOH can be transformed into α-Ga 2 O 3 crystal and form a uniform thin film following post-growth annealing. When the α-Ga 2 O 3 thin film is inserted in between Ni and Si to form a Ni/α-Ga 2 O 3 /Si MIS diode, the barrier height of the diode increases by 0.4 eV and the on/off ratio by 100-fold from those of the Ni/Si Schottky diode. The Ni/α-Ga 2 O 3 /Si MIS diode exhibits a leakage current density of 1.07 × 10 −5 A/cm 2 under −2 V bias. The breakdown voltage of the diode reaches −166 V without the guard ring and other insulation structures. Our results demonstrate that LPD-grown α-Ga 2 O 3 thin films can obtain uniform and dense structure under short deposition time and at an annealing temperature of 400 °C. The uniform insulating layer of α-Ga 2 O 3 has a high potential in enhancing the electrical characteristic of diodes and other power electronic devices.