Piezotronic effect on two-dimensional electron gas in AlGaN/GaN heterostructure

Although the high performance device designs based on piezotronic effect have obtained immense progress, the unique electronic properties of third-generation semiconductor are still required to be deeply illustrated when it is accessible to reveal novel physical states or go beyond performance limitation of traditional semiconductor devices. Strain-produced piezoelectric polarization in the third-generation semiconductors provides a strong power to manipulate the interfacial electronic behaviors particular for two-dimensional electron gas (2DEG) which plays an important role in various exotic quantum states as well as realistic applications. In this study, we base on AlGaN/GaN heterostructure to comparatively explore the impact of piezotronic effect and other effects on the 2DEG. The electron concentration, electrical field, and ground states of the 2DEG are investigated by performing the self-consistent calculation. The results demonstrate that similar to the modulation of gate voltage, stress is also an effective tool to control electron concentration of 2DEG by interfacial piezoelectric field. In contrast with the long-range electric field provided by gate voltage, stress-induced piezoelectric field is very strong short-range field with the level of MV/cm, indicating a more precise mean to control 2DEG. Moreover, piezotronic effect can sufficiently raise the density of state of quantum ground state by decreasing energy level, and thus can be used to enhance Rashba spin-orbit coupling in wide-gap piezoelectric semiconductors. This study provides a deep insight of using piezotronic effect to control the 2DEG, and opens an avenue for manipulating spin degree of freedom.