【Domestic Papers】Growth temperature dependent on the structure, device properties and carrier transport mechanisms of β-Ga₂O₃/GaAs heterojunctions

      Researchers from the Shanghai Dianji University have published a dissertation titled "Growth temperature dependent on the structure, device properties and carrier transport mechanisms of β-Ga₂O₃/GaAs heterojunctions" in Materials Science and Engineering: B.

Project Support

      We acknowledge financial support from National Natural Science Foundation of China (U22A2073, 11974433, 91833301).

Background

      Solar-blind ultraviolet (UV) photodetectors (PDs) are capable of effectively detecting electromagnetic waves in the 200–280 nm range and play a crucial role in applications such as fire detection, ultraviolet early warning, and deep space exploration. Compared to traditional infrared detectors, solar-blind ultraviolet photodetectors benefit from a natural low-background-noise environment. This advantage arises because stratospheric ozone strongly absorbs solar radiation in the 200–280 nm range. Consequently, these detectors achieve high signal-to-noise ratio (SNR) and low error rates. In recent years, a variety of wide bandgap materials have been used for fabricating solar-blind ultraviolet photodetectors, including AlGaN, ZnMgO and Ga₂O₃.

Abstract

      Ga₂O₃ features a wide bandgap and excellent optoelectronic properties, making it highly valuable for applications in UV photodetectors, high-power electronics, and transparent conductive materials. Ga₂O₃ thin films were grown on Si-doped GaAs (100) substrates using pulsed laser deposition technology, followed by the fabrication of Ga₂O_3/GaAs heterojunction solar-blind ultraviolet detectors. High-quality thin films have been achieved by optimizing the growth temperature. As the growth temperature increased from 500°C to 700°C, the particles deposited on the substrate are provided with sufficient energy to migrate and nucleate, resulting in improved crystallinity and reduced defects in the film. Additionally, the presence of an oxygen atmosphere during deposition reduced the concentration of oxygen vacancies, which further minimized oxygen-vacancy-related defects. As a result, the detector exhibits a 164-fold increase in external quantum efficiency, a 241-fold enhancement in responsivity, and a 44.5 % improvement in I_photo/I_dark. These findings provide an experimental foundation for the development of high-performance β-Ga₂O₃/GaAs heterojunction solar-blind UV detectors.

Highlights

      ● Ga₂O₃/GaAs heterojunctions were fabricated on GaAs via PLD for solar-blind UV detection.

      ● Optimized growth temperature (500–700 °C) enhanced Ga₂O₃ crystallinity and reduced defects via improved migration/nucleation.

      ● Detector achieved 164x EQE, 241x responsivity, 44.5% higher I_photo/I_dark, enabling solar-blind detection.

Conclusion

      This work investigates the growth of Ga₂O₃ thin films on Si-doped (100) GaAs substrates using PLD, particularly on the effect of growth temperature. We have shown that the quality of the films significantly improves when the film deposited at a relatively high temperature. This enhancement can be attributed to the high migration rate of the adsorbed atoms on the substrate surface and the crystallization process, leading to better film crystallization and lower defects. Based on the films, Ga₂O₃/GaAs heterojunction UV photodetector with a solar-blind response was fabricated. The device fabricated at 700 ◦C exhibited superior performance, with 164-fold and 241-fold enhancements in EQE and responsivity, respectively, and a 44.5 % improvement in I_photo/I_dark compared to devices based on low-quality β-Ga₂O₃ films. This work provides critical guidance for optimizing β-Ga₂O₃ deposition and developing high-performance β-Ga₂O₃/GaAs heterojunction solar-blind UV photodetectors.