Analytical Modeling of Current Collapse in AlGaN/GaN HFETs According to the Virtual Gate Concept

GaN-based heterostructure field effect transistors (HFETs) have gained considerable attention in high-power microwave applications. So far, unsurpassed current levels and high output power at microwave frequencies have been achieved. However, the dominant factors limiting the reliability of these devices under high-power operation are still unsettled. Drain current collapse is one of the major encumbrances in the development of reliable high-power devices in this technology. In this paper, an accurate and versatile analytical model based on the concept of virtual gate formation due to the existence of acceptor-type surface states is developed to model the current-collapse phenomenon. The presented model is considerably simple, and at the same time, it is more precise than the other analytical models previously proposed in literature. The implementation of this analytical model demonstrates superb agreement with the experimental observations of permanent/semipermanent current collapse in AlGaN/GaN HFETs. To demonstrate the versatility, results of this model are also compared with an existing recently developed analytical model of comparable degree of complexity.