Tailoring the electrical and photo-electrical properties of a WS2 field effect transistor by selective n-type chemical doping

摘要

Here, we demonstrate a doping technique which remarkably improves the electrical and photoelectric characteristics of a WS _(2) field effect transistor (FET) by chemical doping. The shift of the threshold voltage towards a negative gate voltage and the red shift of the E ~(1) _(2g) and A _(1g) peaks in the Raman spectra confirm the n-type doping effect in WS _(2) FETs. WS _(2) films show an unprecedented high mobility of 255 cm ~(2) V ~(?1) s ~(?1) at room temperature. The on/off ratio of the output current is ～10 ~(8) at room temperature. The mobility of a multilayer ML-WS _(2) FET was found to be 425 cm ~(2) V ~(?1) s ~(?1) at 5 K. Semiconductor-to-metal transitions were also observed at V _(bg) > 30 V. A decrease in contact and sheet resistance was observed after potassium iodide (KI) doping. The photocurrent in WS _(2) FETs was also enhanced after n-type doping. Chemical doping exhibited a very stable, effective, and easy-to-apply method to enhance the performance of a WS _(2) FET.