A novel normally-off GaN MISFET with an in-situ AlN space layer using selective area growth

In this paper, we present a recessed-gate normally-off Al₂O₃/AlN/GaN MISFET with stable threshold voltage based on selective area growth (SAG) of AlGaN/GaN heterostructure on AlN/GaN/Si template. By in-situ growth of a thin AlN space layer (SL) in MOCVD, GaO_x can be blocked fundamentally and a high-quality Al₂O₃/AlN/GaN interface is achieved. Thus, the device exhibits a comprehensive upgrade performance with a low threshold voltage hysteresis (ΔV_th) of 75 mV at V_g=10 V, a high peak field-effect mobility (μ_FE) of 187 cm²/V-s, a maximum drain current of 620 mA/mm and an improved frequency dispersion.