High-performance solar-blind photodetectors obtained by temperature-mediated phase control of gallium oxide thin films

Ga 2 O 3 , as an Ultra-Wide-Bandgap (UWBG) semiconductor, has emerged as a highly promising material for high-power electronics and solar-blind photodetectors owing to its exceptional bandgap-related properties. Most relevant studies have focused on optimizing the processing parameters such as annealing temperature, annealing atmosphere and holding time, and aimed to explore the optimal annealing conditions for performance improvement. However, the differential regulatory effects of the initial crystal structure of pre-annealed films (e.g., initial crystallinity, phase composition, and atomic ordering) on crystallization behavior and defect evolution during annealing have been generally neglected. In this work, we systematically investigate the temperature-dependent growth of Ga 2 O 3 thin films deposited at 250 °C, 300 °C, and 350 °C, and further evaluate their performance as the photoactive layers in solar-blind photodetectors before and after post-annealing treatment. We show that the growth temperature plays a decisive role in modulating the crystalline phase and atomic-scale defect landscape of Ga 2 O 3 , which in turn govern the optoelectronic response of the devices. The optimized photodetector delivers a high responsivity of 896.94 A/W, an exceptional photo-to-dark current ratio of 1.14 × 10 8 , an ultralow dark current of 1.13 × 10 −12 A, and an ultrafast response speed, with the comprehensive performance being comparable to or exceeding that of existing solar-blind photodetection technologies. These results demonstrate that precise temperature engineering during the ALD process is an effective route to tailoring phase stability and defect chemistry in Ga 2 O 3 , offering a practical strategy to propel next-generation optoelectronic devices toward higher sensitivity, faster response, and reliable operation under extreme environmental conditions.