Electric Field Distribution Around Drain-Side Gate Edge in AlGaN/GaN HEMTs: Analytical Approach

An analytical model is proposed in this paper for the surface electric field around the drain-side gate edge in the AlGaN/GaN HEMT to which the gate leakage, current collapse, and so on are highly related. Conformal mapping is implemented to mirror the device structure into a simplified geometry and the solution to the Laplace equation is thus achieved. Obtained from the proposed model, the surface electric field in the AlGaN/GaN HEMT shows a high peak around the drain-side gate edge, which is the cause for many reliability issues in HEMTs. The proposed model is then used to study the main factors that may impact the field distribution, such as drain voltage, thickness of barrier, and so on. Numerical simulations are carried out and compared with the analytical model. The high agreement between the results verifies the proposed model.