Current gain above 10 in sub-10 nm base III-nitride tunneling hot electron transistors with GaN/AlN emitter

We report on demonstration of GaN tunneling hot electron transistors (THETA) with dc current gain up to 14.5 in common-emitter configuration, which is highest value reported to date in GaN-based hot electron transistors. THETA is a promising candidate to obtain vertical high frequency transistors in GaN. In a THETA, an emitter-base (EB) barrier is applied to tunnel-inject hot electron beams, and a base-collector (BC) barrier filter cold electrons leak from the base. Under forward operation condition emitter-base bias V _EB <; 0, the injected hot electrons quasi-ballistically transit the base and collector layers, and contribute to the collector current (I _C ). The electrons relaxed within the base due to scatterings and quantum reflections contribute to the base current (I _B ). When the EB junction is sufficiently biased, I _C exceeds IB, resulting in a current gain. In this work, the transistors were designed to have unintentionally doped (UID) GaN/AlN emitter barrier to block low energy electrons, ultra-thin base (<;10 nm) to enhance ballistic transport, and polarization-engineered BC barrier to limit leakage.