Design of β‐Ga₂O₃ Enhancement‐Mode Metal‐Oxide‐Semiconductor Heterojunction Field‐Effect Transistor Using Counter‐Doped β‐Ga₂O₃ Channel

Abstract In this paper, a β‐Ga 2 O 3 enhancement‐mode metal‐oxide‐semiconductor heterojunction field‐effect transistor (MOS‐HJFET) is demonstrated using a counter‐doped β‐Ga 2 O 3 channel, achieved by the diffusion of p ‐type nickel oxide ( p ‐NiO). The junction between the diffused p ‐NiO layer and the β‐Ga 2 O 3 channel forms a depletion region, effectively blocking the channel in the normally‐off transistor. The fabricated β‐Ga 2 O 3 MOS‐HJFET with a counter‐doped β‐Ga 2 O 3 channel achieves a specific on‐resistance (R on,sp ) of 32.6 mΩ·cm 2 , threshold voltage ( V th ) of 1.3 V, supporting a drain current of over 1 mA in the discrete device, and a high on/off current ratio of 10 8 . Furthermore, guidelines for designing the enhancement‐mode MOS‐HJFET are proposed, considering the diffused length of p ‐NiO and the thickness of the β‐Ga 2 O 3 epitaxial layer.