Coeffect of trapping behaviors on the performance of GaN-based devices

Abstract

Trap-induced current collapse has become one of the critical issues hindering the improvement of GaN-based microwave power devices. It is difficult to study the behavior of each trapping effect separately with the experimental measurement. Transient simulation is a useful technique for analyzing the mechanism of current collapse. In this paper, the coeffect of surface- and bulk-trapping behaviors on the performance of AlGaN/GaN HEMTs is investigated based on the two-dimensional (2D) transient simulation. In addition, the mechanism of trapping effects is analyzed from the aspect of device physics. Two simulation models with different types of traps are used for comparison, and the simulated results reproduced the experimental measured data. It is found that the final steady-state current decreases when both the surface and bulk traps are taken into account in the model. However, contrary to the expectation, the total current collapse is dramatically reduced (e.g. from 18% to 4% for the 90 nm gate-length device). The results suggest that the surface-related current collapse of GaN-based HEMTs may be mitigated in some degree due to the participation of bulk traps with short time constant. The work in this paper will be helpful for further optimization design of material and device structures.

Transient response of drain current following biasing stress in GaN HEMTs on SiC substrates with a field plate

“…The existence of two time constants (τ 1 and τ 2 ) indicates that there are two main types of trapping state in GaN HEMTs. 23,24) τ 1 and τ 2 are assumed to correspond to surface donor traps at the interface between the SiN film and the GaN cap layer, and bulk acceptor traps mainly distributed in the GaN buffer layer, respectively.…”