Low Leakage and High I_ON/I_OFF Ratio in Partial Gated AlGaN/GaN Nanowire Field‐Effect Transistors

Abstract

Lateral nanowire (NW) field‐effect transistors are fabricated by a top‐down approach on an AlGaN/GaN heterostructure. A combination of dry and anisotropic wet etching is used to form the NW. The channel is controlled by a 2D electric field originating from two partial gates on the parallel sides of the nanowire channel. While a larger overlap of the gate with the channel region, as in a gate‐all‐around transistor, improves gate control in terms of transconductance gm, gate leakage current and ION/IOFF deteriorate. Partial overlapping gate transistors are found to provide a trade‐off, providing extremely low gate leakage current (≈10 μA cm−2), very low IOFF (100 fA μm−1), and very high ION/IOFF (5 × 108). Despite the nature of the partial gate, a good subthreshold swing (SS) of ≈79 mV decade−1 is observed. Various transistor performance parameters can be tuned within a certain window of trade‐offs between them as the transistor evolves from a partial gate to a gate‐all‐around structure. A 1D nature of the channel near the transistor threshold voltage is found to offset the limitations of the partial gate.