Effect of back barrier with different polarization strengths on two-dimensional electron gas confinement in ScAlN/GaN heterostructures

Abstract The novel heterostructure ScAlN/GaN exhibited a relatively high the two-dimensional electron gas (2DEG) concentration, heightening the risk of 2DEG leakage towards the substrate. Using AlGaN, InAlN, and ScAlN as back barrier layers, this research simulated the influence of material composition and channel layer thickness on 2DEG confinement properties. Results indicate that InAlN exhibited superior confinement due to its stronger polarization effect compared to AlGaN. Conversely, when employed as a back barrier layer, ScAlN's excessively strong polarization effect induced the formation of a secondary electron channel between the back barrier layer and the GaN buffer layer, rendering it unsuitable for this purpose. Concurrently, the optimal composition and channel layer thickness are determined for the back barrier layer. This research provides critical theoretical basis and design guidance for enhancing the reliability of high electron mobility transistors (HEMTs).