【Domestic News】Professor Liu Bo's team from Tongji University：High-resistivity β-Ga₂O₃: Al single crystal and its X-ray detector Obtained by using the band-gap engineering

      Recently, the research team of Professor Liu Bo from Tongji University proposed a design strategy for a high-performance X-ray detector based on β-Ga₂O₃: Al single crystal, and grew high-quality β-Ga₂O₃: Al single crystal by optical floating zone method. The prepared X-ray detector based on Ga₂O₃:15%Al has the advantages of high sensitivity, high response speed and low detection limit. The related research result is published in ACS Applied Electronic Materials, titled “Band gap engineering in β-Ga₂O₃ for a high-performance X-ray detector”.

Abstract

      Ga₂O₃ has an ultra-broadband gap, high breakdown electric field and high X-ray absorption coefficient, which has attracted great attention in the field of X-ray detection. However, unintentional doped Ga₂O₃ tend to have low resistivity because of the shallow donor energy level caused by the impurity elements or the intrinsic defects. Doping of iron and magnesium ions can improve the resistivity of β-Ga₂O₃. However, due to the introduction of deep-level impurities, the carrier drift length and the carrier collection efficiency are greatly reduced. In this paper, the researchers obtained a high resistivity β-Ga₂O₃: Al single crystal by band gap engineering. Meanwhile, the mechanism of Al³⁺ doping on improving the resistivity of β-Ga₂O₃ crystal is discussed, and an X-ray detector based on β-Ga₂O₃:15%Al is developed. The detector has a high sensitivity of 851.6 μC·Gy_air⁻¹·cm⁻², which is 42 times the sensitivity of the commercial amorphous selenium X-ray detector. Moreover, the detector has a fast response speed and a rise time and decay time of less than 0.05s. It was found that the high performance of the X-ray detector based on the β-Ga₂O₃:15%Al is attributed to the high resistivity and high quality of the β-Ga₂O₃: Al crystal. This paper provides a method to obtain a high-performance X-ray detector based on a β-Ga₂O₃ single crystal by band gap engineering.

DOI: 10.1021/acsaelm.1c00778