Technology CAD Modeling of GaN High‐Electron‐Mobility Transistors with Superlattice Buffer Based on Mechanism of Back‐Gate Characteristics

Herein, a technology computer‐aided design (TCAD) model of GaN high‐electron‐mobility transistors (HEMTs) with a simplified AlGaN/AlN superlattice layers (SLs) that can reproduce the back‐gate (BG) characteristics, which reflects properties of the epitaxial structure, is proposed. The physical properties of the SLs, such as carrier accumulation due to internal AlN barriers and traps within SLs, and the movement of carriers through tunneling effects under high electric fields, are considered to influence the BG characteristics. A simplified model of the SL layer that considers the physical properties of the SLs by sandwiching a single AlGaN layer with donor and acceptor traps between AlN layers is proposed. The traps within the AlGaN layer are set to represent carrier accumulation within the SL. The two AlN layers represent the potential barriers between the substrate and AlGaN, and between carbon‐doped GaN (C‐GaN) and AlGaN layers, respectively, and carrier exchange primarily occurs through tunneling. Herein, it is revealed that the donor traps within the simplified SLs model and the potential barriers represented by the two AlN layers significantly affect the waveform of the BG characteristics. The TCAD simulation results calibrated to the experimental results based on the mechanism of the revealed BG characteristics are shown.