Electroluminescence Investigation of the Lateral Field Distribution in AlGaN/GaN HEMTs for Power Applications

The lifetime and stability of AlGaN/GaN heterostructure eld e ect transistors at high power levels can be enhanced by introducing eld plates to reduce electric eld peaks in the gate drain region. Simulations of the electric eld distribution along the channel using the 2D ATLAS software from Silvaco indicate that above a characteristic drain source voltage three spatially separated electric eld peaks appear, one located at the drain-side edge of the gate foot, one at the end of the drain-sided gate eld plate, and one at the end of the source shield eld plate. The close correlation between lateral electric eld and the electroluminescence due to hot electron related intra-band transitions can be very helpful when optimizing the electric eld distribution in high power devices. Electroluminescence microscopy images of devices with gate and source shield eld plate reveal the peaks located at the locations of enhanced electric eld. By studying the voltage dependence of the electroluminescence peaks the in uence of the eld plates on the electric eld distribution in source drain direction can be visualized.