2D Hole Gas at GaN/AlN Interface—An Unprecedented Platform to Probe the Valence Band of GaN

The advent of p-type GaN has changed the world forever. To date most of the p-type GaN has been achieved by impurity doping, i.e. replacing Ga with Mg in the GaN semiconductor crystal. A few years back Chaudhuri et al [Science 2019] demonstrated that it is possible to form a 2D hole gas at the GaN/AlN interface without impurity dopants, which arises from the discontinuity of polarization at this heterointerface. This 2D hole gas is free from dopant scattering and freeze-out, just like its counterpart – the 2DEG at an AlGaN/GaN interface. As a result, it provides an unprecedented platform for us to probe the valence band of GaN. I will share our recent discoveries of Shubnikov-de Haas oscillation and cyclotron resonance of heavy holes and light holes, all thanks to these unique 2D hole gases.