Nanoscale AgInTe₂/Si Truncated Quasitetrahedrons for Heterostructured Photodetectors

Group I–III–VI2 semiconductors are promising for the fabrication of electronic and photoelectronic devices because of their tunable band gaps and intensive absorption in visible and near-infrared regions. Here, ternary AgInTe2 nanostructures have been synthesized via a facilely designed solution-phase procedure at 240–280 °C from AgNO3 and In(acac)3 in oleylamine reacted with TeO2 dissolved in 1-dodecanethiol. They illustrate truncated quasitetrahedrally geometrical shapes from the phosphine-free solution synthetic route and could be spin-coated on silicon wafer to set up a vertical AgInTe2/Si heterojunction-based photodetector. The device is highly sensitive to visible and near-infrared illuminance and has remarkable photoresponsive properties with an on/off switch ratio of 780 at a reverse bias of −5 V, a high responsivity (2.82 A W–1), specific detectivity (8.12 × 1011 Jones), and a low noise equivalent power (2.46 × 10–13 W Hz–1/2) at a bias of −2 V. Especially, the device exhibits fast response speeds (τrise = 5.2 μs, τfall = 18.4 μs), which would be a vital figure of merit for its technical application. The present work offers an available strategy for the tunable synthesis of ternary and even multiple-component tellurides beyond the demonstrated high-quality AgInTe2 nanostructures and would provide a simplified way to heterostructure-based photodetectors with high-responsivity and fast-speed performances.