Optimization of an enhancement-mode AlGaN/GaN/AlGaN DHFET towards a high breakdown voltage and low figure of merit

Demonstrated in this work are the effects of lateral scaling on the figure of merit (R_DS(on)×Q_G) for a pGaN, enhancement-mode HEMT. To this end, the drift length (L_drift) and the length of the gate field plate (L_GFP) have been scaled to exhibit the influence of these terms on the on-state resistance (R_DS(on)), gate charge (Q_G), and breakdown voltage (V_BR). Results conclude that for a given field plate length, the increase in breakdown voltage as L_GD increases, saturates when L_GD is greater than L_GD(sat). For this design, with L_GFP at 5 μm, the saturation length L_GD(sat) was 6 μm. Novelty of this study comes from a comprehensive look at drift length and field plate optimization for high voltage and low figure of merit designs, specifically for the enhancement-mode pGaN structure. Taking this optimization one step further, we have mapped out R_DS(on) and Q_G to suggest designs which optimize conduction losses versus switching losses for specificity in power electronics system design.