High-speed ultraviolet-visible-near infrared photodiodes based on p-ZnS nanoribbon-n-silicon heterojunction

Ag-doped p-type ZnS nanoribbons (NRs) with a high hole concentration of 5.1 x 10(18) cm(-3) and high carrier mobility of 154.0 cm(2) V-2 s(-1) were synthesized by using silver sulfide (Ag2S) as the Ag source. Excellent ohmic contact to p-ZnS NR with specific contact resistivity as low as 5.6 x 10(-7) Omega cm(2) was achieved by using bilayer Cu (4 nm)-Au electrode, which according to the depth profiling X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) analysis can help to form a thin Cu2S interfacial layer between the electrode. Based on the high quality ZnS NRs and achievement on ohmic contact, p-n photodiodes have been constructed from the p-ZnS nanoribbon (NR)-n-Si heterojunction with a response speed as high as similar to 48 mu s (rise time). Furthermore, the device also exhibits stable optoelectrical properties with high sensitivity to UV-visible-NIR light and an enhancement of responsivities of 1.1 x 10(3) AW(-1) for 254 nm under a reverse bias of 0.5 V. These generality of the above results shows that the p-ZnS NR-n-Si heterojunction will have potential applications in future high-performance photodetectors.