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

Abstract

Ag-doped p-type ZnS nanoribbons (NRs) with a high hole concentration of 5.1 × 1018 cm−3 and high carrier mobility of 154.0 cm2 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 × 10−7 Ω cm2 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 ∼48 μs (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 × 103 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.