Formation of two-dimensional electron gas at AlGaN/GaN heterostructure and the derivation of its sheet density expression**Project supported by the National Natural Science Foundation of China (Grant Nos. 61377020, 61376089, 61223005, and 61176126) and the National Science Fund for Distinguished Young Scholars, China (Grant No. 60925017).

Abstract

Models for calculating the sheet densities of two-dimensional electron gas (2DEG) induced by spontaneous and piezoelectric polarization in AlGaN/GaN, AlGaN/AlN/GaN, and GaN/AlGaN/GaN heterostructures are provided. The detailed derivation process of the expression of 2DEG sheet density is given. A longstanding confusion in a very widely cited formula is pointed out and its correct expression is analyzed in detail.