Thermal engineering in ALD-grown ZGO thin films for high-performance photodetectors

Doped gallium oxide-based thin films are a class of wide-band semiconductor materials with the advantages of chemically stable, tunable bandgap, and offer the benefit of ultraviolet response. In order to obtain photodetectors (PDs) with superior response, higher demands are placed on the quality of growth and processing of doped films. In this work, Zn-doped ternary metal oxide ZnGaO (ZGO) thin films were grown using the atomic layer deposition technique and annealed at different temperatures under an oxygen atmosphere. The results showed that the high-quality ZGO films with good uniformity, high visible light transmittance, low roughness, and significant reduction of oxygen vacancies were obtained after annealing. Subsequently, metal-semiconductor-metal PDs were prepared based on the studied ZGO films. The responsivity (R), detectivity (D*), and external quantum efficiency (EQE) of the optimized device are 61.8 A W–1, 1.2 × 1012 Jones, and 255.9 %, respectively. Compared to the unannealed device, the annealed ZGO PD achieves a maximum 309-fold increase in responsivity. This thermal engineering work may provide a strong reference for the development of low-cost, large-area, high-performance ultraviolet detection. And it also broadens the application of ternary metal oxides in optoelectronics.