Analytical Modeling and Simulation Study of Thickness of AlN Spacer on Electrical Properties of AlGaN/AlN/GaN HEMT Device

In this study, the impact of AlN spacer layer thickness on AlGaN/AlN/GaN HEMT device performance has been investigated. Electrical characteristics of the device are numerically simulated using MATLAB, and the structure design and physical properties are observed using SILVACO ATLAS TCAD. The primary findings of this research show that sheet carrier density increases with increasing AlN thickness because introducing the spacer layer (AlN) at the AlGaN/GaN interface leads inside a significant rise in the polarization field, high barrier, and significant conduction band off set. Primarily, the 2DEG density increases and reduces the scattering present at the interface. Due to the binary nature of the AlN material, the other scatterings that are present in standard AlGaN/GaN HEMT are minimized. It is noted that the threshold voltage varies inversely with spacer thickness and can be increased by using a very thin spacer. The threshold voltage is predicted with the modification of spacer layer thicknesses that have been plotted. A positive threshold voltage is observed for thicknesses below 0.5 nm, and above this thickness, a negative threshold voltage is observed in our study. All analyses and results are performed and obtained in the simulation tools.