Novel Ternary Nitride Thin Film‐Based Self‐Powered, Broad Spectral Responsive Photodetector with a High Detectivity for Weak Light

Abstract Self‐powered, wide‐spectral response, fast, and high‐sensitivity photodetectors are essential for developing next‐generation optoelectronic devices. In this work, the predicted optoelectronic properties of the ternary metal‐zinc (Zn)‐nitride (N) thin films are experimentally demonstrated. A novel phase of the Titanium (Ti)‐Zn‐N system (dominantly TiZnN₂ film of ≈235 nm thickness) is developed on the p‐Si substrate, which shows excellent optoelectronic properties. The Indium Tin Oxide (ITO)/TiZnN₂/p‐type Si (p‐Si) photodetector of area ≈4 mm² exhibits an impressive responsivity of 1.22 × 10^–4 A W⁻¹ at 0 V and 40 mA W⁻¹ at −4 V, a specific detectivity up to 1.16 × 10⁹ Jones at 0 V, and a response speed of 1.9 ms at zero external bias (i.e., self‐powered mode). Benefiting from the broad‐band absorption of the film and p‐Si combination, the detection range is observed from the ultraviolet to near‐infrared (300–1150 nm). Simultaneous operation of self‐powered photo‐triggered drip irrigation ON and street light OFF in the early morning and vice‐versa in the evening is demonstrated for autonomous farming. The device is insensitive to humidity and ambiance, and generates a photocurrent with light intensity as low as 5 mW cm⁻². The active layer is hydrophobic and highly stable, and the fabrication is cost‐effective.