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

In this paper, a β‐Ga2O3 enhancement‐mode metal‐oxide‐semiconductor heterojunction field‐effect transistor (MOS‐HJFET) is demonstrated using a counter‐doped β‐Ga2O3 channel, achieved by the diffusion of p‐type nickel oxide (p‐NiO). The junction between the diffused p‐NiO layer and the β‐Ga2O3 channel forms a depletion region, effectively blocking the channel in the normally‐off transistor. The fabricated β‐Ga2O3 MOS‐HJFET with a counter‐doped β‐Ga2O3 channel achieves a specific on‐resistance (Ron,sp) of 32.6 mΩ·cm2, threshold voltage (Vth) of 1.3 V, supporting a drain current of over 1 mA in the discrete device, and a high on/off current ratio of 108. Furthermore, guidelines for designing the enhancement‐mode MOS‐HJFET are proposed, considering the diffused length of p‐NiO and the thickness of the β‐Ga2O3 epitaxial layer.