Dual-channel design to suppress buffer induced current degradation in AlGaN/GaN heterostructures on Si.

ABSTRACT

We design a dual-2DEG (Two dimensional electron gas) channel structure to suppress the buffer induced current degradation in AlGaN/GaN based heterostructures on Si. The epitaxial structure includes two AlGaN/GaN interfaces, and therefore induces two 2DEG channels at each interface. The upper 2DEG channel acts as the current transport channel (the working channel) while the bottom channel is used to shield the buffer charge induced electric field. Thus, the current in the upper channel keeps stable in regard of the trapping phenomenon in the buffer layers. Pulse stress measurements and back-gating sweep measurements are conducted to evaluate the current stability in the dual-channel structure. A normal single-channel AlGaN/GaN heterostructure is also tested as comparison. The current stability of the dual-channel structure in the pulsed stress measurement is better than the single-channel sample. The back-gating sweep measurement results further confirm the electric filed shielding mechanism of the bottom channel.