Influence of a piezoelectric field on the electron distribution in a double GaN/Al0.14Ga0.86N heterojunction

C–V profiling of Al0.14Ga0.86N/GaN heterojunctions was performed. It was found that a heterojunction with the Al0.14Ga0.86N layer on top increases the electron concentration at the Al0.14Ga0.86N/GaN interface, while the reversed structure with the GaN layer on top decreases it. In accordance with this result, an Al0.14Ga0.86N/GaN double heterojunction was found to experience a strongly asymmetric electron distribution with an enhancement of the electron concentration at the interface closest to the sample surface. This effect is attributed to the presence of a piezoelectric field redistributing the electrons in the heterostructure.