ABSTRACT
As Figure 6.1 shows, GaN serves as the material for both the buffer layer and the channel in conventional AlGaN/GaN heterostructures. Owing to the lower barrier height formed in GaN under the channel, the easy spillover of channel carriers into the buffer layer to become three-dimensional electrons at high temperature or a relatively high gate/drain voltage leads to a reduced 2DEG confinement and performance degradation. The short channel effect also causes soft channel pinch-off and large offstate leakage currents in deep submicrometer GaN HEMTs.
