Viterbi Faculty of Electrical Engineering, Technion
Evaluation of the density of interface states in GaN using the UV assisted gated van der Pauw method
The two-dimensional electron gas (2DEG) at the interface between GaN and other polar semiconductors is induced by the spontaneous and piezoelectric polarization of these materials. The model that presently explains the formation of the 2DEG assumes that the source of the 2DEG is surface donors (or surface traps). In order to critically evaluate this model, we have measured the density of traps at the SiN/GaN interface of a SiN/GaN/AlGaN/GaN heterojunction by the newly developed UV assisted gated van der Pauw method. In this talk, I will introduce the newly developed method, and report that the obtained values are about two orders of magnitude lower than assumed by the surface donor theory, and much lower than required to compensate the polarization surface charge in bulk GaN. We hence conclude that variable mid gap surface charge is not responsible for the formation of the 2DEG, and cannot compensate the large surface polarization charge in GaN. A fixed, yet unexplained, surface charge must be invoked to account for experiments. * MSc seminar under supervision of Prof. Dan Ritter.
Date: Mon 28 Jan 2019
Start Time: 14:30
End Time: 15:30
1061 | Electrical Eng. Building