Ga2O3 has emerged as a promising material offering broad potential for device applications. To optimize the performance of Ga2O3-based devices, doping and annealing are widely employed to modulate composition and phase. For amorphous Ga2O3 thin films, atomic layer deposition (ALD) is recognized as an advanced technology with distinct advantages. Recently, amorphous Ga2O3 has been applied in photoelectric synaptic devices for neuromorphic computing, with oxygen vacancies (VO) as primary defects modulating performance. Moreover, VO defect engineering through annealing can reduce VO concentration and improve photoelectric performance. Herein, Si-doped Ga2O3 thin films were deposited by plasma-enhanced ALD and annealed in various atmospheres with comprehensive characterizations. Two-terminal devices were fabricated using as-deposited and annealed samples with electrical characterizations. For dielectric applications, breakdown and capacitance–voltage characterizations were performed, revealing a general breakdown voltage of over 30 V and a breakdown electric field of over 2.6 MV/cm under the annealing effect. Subsequently, photoelectric characterizations of both the photoelectric synaptic devices based on as-deposited thin films and the photodetector based on annealed thin films were performed. The short-term plasticity, paired-pulse facilitation (PPF), and long-term plasticity were characterized for photoelectric synaptic devices, demonstrating a PPF index of over 115% with acceptable signal processing and memory capabilities. Moreover, the photodetectors based on the annealed thin films exhibited a maximal on/off ratio of 1050%, indicating available detection efficiency under the annealing effect. Finally, the mechanism of annealing effect on device functionality transition was analyzed and explained by the VO concentration variation and defect engineering from multiple perspectives.
Wei et al. (2026) studied this question.