Modeling the processes of formation of defects that form deep levels in SiON/AlGaN/GaN

Abstract

The effect on the electrical parameters of the SiON/AlGaN/GaN structures of treatment of different durations of low-energy nitrogen plasma was studied. The AlGaN surface was subjected to plasma treatment in the working chamber of the plasma-chemical deposition unit before starting the monosilane to form the SiON film. Changes in the transport properties (conductivity and mobility) of the canal and capacitive properties of the structures were evaluated. It has been experimentally shown that such treatment leads to a change in the magnitude of polarization charges both at the insulator-AlGaN interface and at the AlGaN/GaN interface. With the help of C–V measurements-in the hysteresis mode, it is shown that at the control voltage U > +4 — +5 V ), some of the channel electrons are captured at deep centers at the SiON-AlGaN interface, and with an increase in the duration of exposure to plasma time, a sharp increase is observed charge Qit, formed by electronic boundary states. The use of additional treatment with nitrogen plasma transfers work for nitride structures from the D-mode (Vth = –4 V) to the E-mode (Vth = +0.9 V).Using Auger-measurements, it was shown that plasma treatment leads to a change in the amount of oxygen in the SiON layer and in nano-regions of the barrier layer, and with an increase in the duration of plasma exposure, a sharp decrease in the amount of oxygen in these layers is observed. Also, when using plasma treatment, the redistribution of Ga and Al at the AlGaN–GaN interface i.e. in the channel area. Using Auger measurements near the SiON–AlGaN interface from the side of the insulator, the localization of nitrogen atoms chemically bonded with silicon N(Si) with the formation of a peak at the interface, the size of which increases with increasing duration of plasma exposure.