Analysis of Breakdown Characteristics in Gate and Source Field-Plate AlGaN/GaN HEMTs

H. Onodera, H. Hanawa, K. Horio
Shibaura Institute of Technology, JP

Keywords: GaN HEMT, field plate, breakdown voltage


AlGaN/GaN HEMTs are now receiving great attention because of their applications to high-power microwave devices. It is known that the introduction of field plate enhances the power performance of AlGaN/GaN HEMTs, because the off-state breakdown voltage increases. Usually, the breakdown voltage increases with increasing the field-plate length, because the electric field at the drain edge of the gate decreases. However, in devices with small dimensions, the situation may become different. In this work, we have made two-dimensional analysis of field-plate AlGaN/GaN HEMTs with a short gate length (0.3 μm) and a relatively short gate-to-drain distance (1.5 μm), and found that the breakdown voltage can decrease with the field-plate length and its optimum value exists. We also compare the breakdown voltage between gate and source field-plate structures and discuss which structure has higher breakdown voltages.