Ultrathin CdSe nanowire field-effect transistors

Abstract

We report the fabrication, and electrical and optical characterization, of solution-liquid-solid (SLS) grown CdSe nanowire field-effect transistors. Ultrathin nanowires (7–12 nm diameters) with lengths between 1 µm and 10 µm were grown by the SLS technique. Al-CdSe-Al junctions are then defined over oxidized Si substrate using photolithography. The nanowires, which were very resistive in the dark, showed pronounced photoconductivity even with a visible light source with resistance decreasing by a factor of 2–100 for different devices. Field-effect devices fabricated by a global backgating technique showed threshold voltages between −7.5 V and −2.5 V and on-to-off channel current ratios between 10³ and 10⁶ at room temperature. Channel current modulation with gate voltage is observed with the current turning off for negative gate bias, suggesting unintentional n-type doping. Further, optical illumination resulted in the loss of gate control over the channel current of the field-effect transistor.