Simulation-based optimization of barrier and spacer layers in InAlN/GaN HEMTs for improved 2DEG density

Abstract

In this study, we utilize Nextnano device simulation software to systematically investigate the dependence of 2-DEG (two-dimensional electron gas) density on the barrier and spacer Layers in InAlN/GaN high electron mobility transistors (HEMTs). By simulating a range of barrier thicknesses, In mole fractions, and spacer layer thicknesses, we reveal the intricate ways in which these parameters influence device performance. Our simulations demonstrate that precise control of the InAlN barrier thickness and In mole fraction, along with the AlN spacer thickness, is crucial for optimizing 2DEG density and, consequently, the overall electrical properties of the HEMTs. Notably, our results highlight that an InAlN barrier thickness below 12 nm, coupled with an optimized In mole fraction and a finely tuned AlN spacer thickness close to 1 nm, significantly enhances 2DEG density without compromising mobility. These insights provide a detailed understanding of the material and structural dependencies critical for the design and development of high-performance InAlN/GaN HEMTs. Our study includes detailed calculations of the device's I–V characteristics. Notably, the highest peak output current is observed at a 1 nm AlN spacer thickness, reaching 0.91 A/mm. Our findings highlight a noteworthy agreement between the results derived from our computational simulations and experimental measurements.