Low-Temperature-Crystallized Ga₂O₃ Thin Films and Their TFT-Type Solar-Blind Photodetectors

Crystalline Ga₂O₃ (c-Ga₂O₃) is a promising candidate for next-generation solar-blind photodetectors (SBPDs) but is suffering from high processing temperatures. Herein, seed-induced engineering is proposed via adopting Zn as an induced metal for crystallizing Ga₂O₃, lowering the processing temperature by 200 °C. After annealing, the Zn/Ga₂O₃ consists of an inner Ga₂O₃ layer of a monoclinic crystalline phase, top ZnO crystals coming from Zn oxidation, and a thin corundum Ga₂O₃ layer between them, which implies a "seed-induced" crystallization mechanism besides the nonequilibrium chaotic state caused by the traditional electron transfer one. As a result, the tailored c-Ga₂O₃ thin-film transistor-type SBPD with enhanced packing density and finite oxygen deficiency demonstrates a satisfactory responsivity of 8.6 A/W and also an ultrahigh UVC/visible rejection ratio (R₂₅₄/R₄₅₀) of 2 × 10⁵. The seed-induced engineering forecasts its potential application in crystalline Ga₂O₃ SBPDs under a relatively low processing temperature.