Investigation into the Energy Band Diagram and Charge Distribution in AlGaN/GaN Double Heterostructures by Self-Consistent Poisson--Schrödinger Calculations

The energy band diagram and charge distribution of the unintentional doped AlGaN/GaN/AlGaN/GaN double heterostructure were obtained by self-consistent Poisson--Schrödinger calculations. The severe band tilting and high two-dimensional electron gas (2DEG) density mainly attribute to the large internal polarization intensity, which is close to a linear function of Al composition. The influence of Al composition is investigated. The results show that band tilting enlarges and 2DEG gains with Al composition, and two-dimensional hole gas occurs when Al composition reaches a certain extent. The influence of Al composition and two-dimensional hole gas (2DHG) on devices is discussed.