All‐Oxide Transparent Vertical Indium Tin Oxide and Aluminum‐Doped Zinc Oxide/ β ‐Ga 2 O 3 Schottky Diodes

Herein, the fabrication and characterization of low‐resistance all‐oxide transparent vertical β ‐Ga 2 O 3 diodes using indium tin oxide (ITO) and aluminum‐doped zinc oxide (AZO) Schottky contacts are reported. It is shown that an ITO ohmic contact to n + ‐ β ‐Ga 2 O 3 substrate is formed after annealing in N 2 at 800 °C. Both AZO‐ and ITO‐based Schottky diodes show well‐behaved current–voltage characteristics. Average Schottky barrier heights and ideality factors are 0.99 and 1.05 eV and 0.95 and 1.03 eV for AZO and ITO Schottky contacts, respectively. The on‐off current ratio is about 210 10 and 110 10 for AZO and ITO Schottky contact, respectively. Moreover, the on‐state resistance is about 6–7 and 4–5 mΩ cm 2 for AZO and ITO Schottky contact, respectively, and is 20–35 times lower than for previously reported transparent β ‐Ga 2 O 3 Schottky diodes.