【Domestic Papers】Tuning the structural, electronic, and transport properties of ferroelectric‑zinc blende phase Ga₂O₃ monolayer by Si dopant and biaxial strain

      Researchers from Jiangxi University of Science and Technology have published a dissertation titled " Lightwave-annealed a-Ga₂O₃ phototransistors with record specific detectivity (>10¹⁸ Jones) for weak-UV detection " in Applied Surface Science

Background

      Solar-blind ultraviolet photodetectors (SBUV PDs) operate in the 200–280 nm wavelength band (the “solar-blind region”). This region features nearly zero solar radiation at the Earth's surface. This characteristic enables high-precision, low-noise UV detection, demon strating exceptional target recognition and sensing capabilities in com plex interference environments. Because of this, the SBUV PDs with high responsivity and high detectivity plays an irreplaceable role in the field of precision measurement and analysis: in environmental and meteo rological monitoring, it is used to capture the slow-changing but extremely weak signals in ozone hole observation and UV index moni toring; in biochemical sensing and spectroscopy, it is responsible for the detection of weak fluorescence or phosphorescence stimulated by UV; in the weak light UV imaging and laboratory precision optical measure ments, it is used to identify and sense targets by means of a low-noise background; in the weak light UV imaging and laboratory precision optical measurements, it provides the possibility of generating high quality images and data by effectively accumulating weak photon signals.

Abstract

      Amorphous gallium oxide (a-Ga₂O₃) phototransistors are promising for solar–blind ultraviolet (SBUV) detection, yet their performance is limited by high defect density and poor carrier transport. To address the critical challenge of achieving high-performance a-Ga₂O₃ phototransistor for low-intensity UV detection, this study in troduces lightwave annealing as a post–fabrication treatment designed to effectively improve the film quality of a-Ga₂O₃. Compared with vacuum-annealing, the optimized lightwave annealing method can significantly reduce the V_O content, widen the band gap and increase the relative mass density, indicating a denser film with improved film quality. This optimization strategy enhances the responsivity by up to approximately 4000 times even under weak UV illumination (0.741 μW/cm²), increases the specific detectivity (D^*) exceed 10¹⁸ Jones, and shortens the response time by an order of magnitude. This work not only achieves high detectivity and high responsivity in weak-UV-light detection but also elucidates the underlying mechanism of V_O regulation via lightwave annealing.

Conclusion

      The study systematically investigates the modulation mechanism of the lightwave annealing process on the performance of a-Ga₂O₃ thin films and their a-Ga₂O₃ phototransistors. The lightwave annealing can effectively promote the structural rearrangement and defect repair of a-Ga₂O₃ thin films through photon-thermal synergy. Compared with vacuum annealing, the optimized lightwave annealing method can significantly reduce the V_O content, widen the band gap, and increase the mass density, thereby promoting film densification. The overall improvement of film quality is the fundamental reason for the device to realize excellent optoelectronic performance. These results elucidate that lightwave annealing provides a key technological path to break through the performance bottleneck of a-Ga₂O₃ phototransistors in weak-light detection.

Project Support

      This project is supported by the Natural Science Foundation of China (62274166).

Fig. 1. XPS analysis of a-Ga₂O₃ films under varied annealing conditions.(a–d) O 1s XPS spectra for samples: (a) vacuum-400 ◦C, (b) LW-40 min, (c) LW-50 min, and (d) LW-60 min. (e) Quantitative area percentage of M–O, V_O, and –OH components across annealing methods, extracted from XPS spectral deconvolution.

Fig. 2.Optical and structural characterizations of a-Ga₂O₃ films under different annealing conditions. Curves correspond to vacuum-400 ℃ and LW-40 min, LW-50 min, LW-60 min, respectively. (a) Plots of (αhν)² versus photon energy (hν), where shows the corresponding band gaps obtained by the Tauc plot method. (b) Refractive index as a function of wavelength for a-Ga₂O₃ films with different annealing conditions. The inset shows a magnified view of the n at 1700 nm; (c) Magnified view of the XRR spectra, with θ_c representing the all-external-reflection critical angle. (d) Summary of key optical parameters: E_g(top), n@1700 nm(middle), and ρ(bottom).

Fig. 3. (a)Response spectra for samples: vacuum annealed at 400 ℃ (measured at V_GS =V_on and V_GS =50 V) , LW-40 min (measured at V_GS =V_on and V_GS =50 V)，LW-50 min (measured at V_GS =V_on and V_GS =41 V), and LW-60 min (measured at V_GS =V_on and V_GS) =50 V).(b)Schematic diagram of the a-Ga₂O₃ phototransistor structure PDCR, D^* and EQE as a function of different annealing conditions.(c)Summary of t_rise and t_fall at 254 nm wavelength for devices with varied annealing processes.(d)Summary of R₂₅₄/R₃₂₀ and R₂₅₄/R₄₅₀ for devices with varied annealing processes.(e)Comparison of R_max and D^* between Lightwave annealed devices and typical reported a-Ga₂O₃ SBPD.

Fig. 4. Schematic representation of the microstructural evolution of a-Ga₂O₃ thin films during lightwave annealing process.

DOI：

doi.org/10.1016/j.apsusc.2026.166659