Numerical Investigation of Quasi‐Vertical GaN‐on‐Si MOSFET Incorporating AlGaN/GaN Polarization Interface and AlGaN Functional Layer

In this work, we systematically investigate a quasi‐vertical GaN‐on‐Si MOSFET by incorporating a graded Al x → y Ga 1‐ x →1‐ y N functional interlayer between the p‐GaN layer and n ‐ ‐GaN drift layer. The Al x→y Ga 1‐ x →1‐ y N layer with a gradually decreasing Al composition forms a negative bulk charge that expands the distribution of the depletion region in n ‐ ‐GaN. Therefore, the introduction of a graded AlGaN layer enhances the off‐state characteristics, which is attributed to the reduced electric field intensity near the corner of the trench gate. Moreover, the graded Al x → y Ga 1‐ x →1‐ y N layer can also increase the potential barrier in the n ‐ ‐GaN drift layer, resulting in a reduced drain‐source leakage current (I DSS) . During the on‐state, the graded Al x → y Ga 1‐ x →1‐ y N layer can also effectively enhance the lateral current spreading effect due to the 2D electron gas (2DEG) with high electron mobility at the AlGaN/GaN polarization interface. This results in an increase in the on‐state current density.