Ultralow-voltage and high gain photoconductor based on ZnS:Ga nanoribbons for the detection of low-intensity ultraviolet light

Abstract

A low-intensity ultraviolet photodetector (PD), with a gain as high as ∼2.4 × 10⁶, has been successfully constructed based on gallium (Ga) doped zinc sulfide (ZnS) nanoribbons (NRs). The device exhibits excellent photoconductive properties upon a bias voltage as low as ∼0.01 V in terms of high sensitivity to UV light with an intensity of 1 μW cm⁻² (corresponding to an incident power of 10⁻¹⁴ W), relatively fast response times of ∼3.2 ms, and an extremely high detectivity of ∼1.3 × 10¹⁹ cm Hz^1/2 W⁻¹. The high gain and fast response time are attributed to the excellent ohmic contact obtained by using a high quality ITO electrode and having a carrier mobility as high as 130 cm² V⁻¹ s⁻¹, which was confirmed from the back-gate field effect transistors. These results show that the single-crystalline n-type ZnS:Ga NRs will have potential applications in future high-performance low-intensity ultraviolet photodetectors.