High-performance CdSe nanobelt based MESFETs and their application in photodetection

Abstract

High performance metal–semiconductor field-effect transistors (MESFETs) based on single n-CdSe nanobelts (NBs) have been fabricated and applied as photodetectors. Au is used as the gate metal, which formed a good Schottky contact with the CdSe NB with a rectification ratio of about 2 × 10⁸. The CdSe NB MESFETs exhibit a near-zero threshold voltage (−0.55 V), low subthreshold swing (60.4 mV per dec), no clearly observed current hysteresis, and the highest on/off current ratio (5 × 10⁸) reported so far for NW/NB MESFETs. We have also investigated the photoresponse properties of these MESFETs. Typical CdSe NB MESFET based photodetectors have high current responsivity (∼1.4 × 10³ A W⁻¹), high gain (∼2.7 × 10³), and fast photoresponse speed (the rise time and the decay time are about 35 and 60 μs, respectively.) under a gate voltage of −1 V. All these results show that the CdSe NB based MESFETs can be promising candidates for both electronic and opto-electronic nanodevices.