Silver telluride quantum dots on silicon near-infrared photodetectors

Silver telluride Ag2Te quantum dots (QDs) are a new type of narrow bandgap, heavy metal-free quantum dots with promising applications in infrared imaging, near-infrared detectors, solar cells and biomedicine. In this study, a silicon-based Ag2Te quantum dot near-infrared photodetector was designed and prepared, and the photodetector device was constructed by directly coating Ag2Te quantum dot solution on a single-crystal silicon substrate in order to evaluate the photodetection performance of colloidal quantum dots and its feasibility for large-scale silicon-based integration. Firstly, Ag2Te quantum dots were synthesised by thermal injection, resulting in quantum dots with an average size of about 5 nm and a band gap of 0.73 eV. The fabricated Ag2Te quantum dots were successfully deposited on silicon wafers using the solution method after the ligand exchange, and gold electrodes were deposited to fabricate the near-infrared photodetectors. Tests show that the photodetectors prepared based on silicon and quantum dots have excellent performance under room temperature 1050 nm illumination, with a response up to 150 A/W and a specific detectivity up to 2.3 × 1010 Jones.In addition, the effects of the electrode position and the thickness of the quantum dot film on the performance of the devices are investigated, and a carrier migration model is given for carriers within the material at different thicknesses. This study is not only a reference for the preparation of silver telluride near-infrared colloidal quantum dots for photodetector applications, but also confirms the feasibility of colloidal quantum dots silicon-based large-scale integration.