Enhancing the electrical performance of InAs nanowire field-effect transistors by improving the surface and interface properties by coating with thermally oxidized Y2O3

Abstract

Due to their excellent electrical characteristics, InAs nanowires (NWs) have great potential as conducting channels in integrated circuits. However, the surface effect and loose native oxide coverage can deteriorate the performance of InAs NW transistors. Y₂O₃, a high-k dielectric with low Gibbs free energy, has been proposed to modify the InAs NW surface. Here, we systematically investigate the effect of Y₂O₃ coating on the performance of InAs NW field-effect transistors (FETs). We first explore the influence of the thermal oxidation process of Y₂O₃ on the performance of back-gated FETs. We then observe that the coverage of Y₂O₃/HfO₂ bilayers on the NW decreases the hysteresis (the smallest value reaches 0.1 V), subthreshold swing (SS, down to 169 mV dec⁻¹) and on-state resistance R_on, and increases the field-effect mobility μ_FE (up to 4876.1 cm² V⁻¹ s⁻¹) and the on–off ratio, mainly owing to the passivation effect on the NW surface. Finally, paired top-gated NW FETs with a Y₂O₃/HfO₂ bilayer and a single layer of HfO₂ dielectric are fabricated and compared. The Y₂O₃/HfO₂ bilayer provides better gate control (SS_min = 113 mV dec⁻¹) under a smaller gate oxide capacitance, with an interface trap density as low as 1.93 × 10¹² eV⁻¹ cm⁻². The use of the Y₂O₃/HfO₂ stack provides an effective strategy to enhance the performance of III–V-based transistors for future applications.