Accumulation hole layer in $p-GaN/AlGaN$ heterostructures Available to Purchase

We present the results on piezoelectric and pyroelectric doping in AlGaN-on-GaN and GaN-on-AlGaN heterostructures and demonstrate $p-GaN/AlGaN$ structures with accumulation hole layer. Our results indicate that polarization charge can induce up to $5×1013 cm−2$ holes at the AlGaN/GaN heterointerfaces. We show that the transition from three-dimensional (3D) to two-dimensional (2D) hole gas can be only achieved for hole sheet densities on the order of $1013 cm−2$ or higher. At lower densities, only 3D-hole accumulation layer may exist. These results suggest that a piezoelectrically induced 2D-hole gas can be used for the reduction of the base spreading resistance in AlGaN/GaN-based heterostructure bipolar transistors.