On the Time-Dependent Transport Mechanism Between Surface Traps and the 2DEG in AlGaN/GaN Devices

The physical mechanisms involved in the trapping and de-trapping processes associated with surface donor traps in gallium nitride (GaN) transistors are discussed in this paper. The paper challenges the conventional transient techniques adopted for extrapolating the trap energy level via experiments and TCAD simulations. Transient TCAD simulations were employed to reproduce the time-dependent electrical behavior of a metal-on-insulator field-effect transistor and explain the influence of the electric field and energy barrier on the transient time associated with the trapping and de-trapping mechanisms of surface traps. The comparison between three test structures and the relative variation of the trapping and de-trapping times with the bias and trap parameters leads to the suggestion of a proposed test structure and bias configuration to accurately extrapolate the energy level of surface traps in GaN transistors.