Southeast University successfully prepared new X-ray detector semiconductor materials
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〠Instrument R & D 】 In 1895, German physicist Roentgen discovered that X-ray, physics, chemistry, biology, material science and many other scientific fields have ushered in a new way of studying material composition and structural information. Research advances in the field of X-rays such as characteristic X-rays, X-ray diffraction, X-ray spectroscopy, X-ray photoelectron spectroscopy, etc. have made X-ray instruments an indispensable device for modern scientific research. In the development of X-ray instruments, in addition to the theoretical study of X-ray physical characteristics, the development of the instrument itself cannot be ignored.
X-ray detector is one of the core components of X-ray instrument. As an integral part of the X-ray imaging system, the X-ray detector is responsible for converting X-ray energy into an electrical signal that can be recorded. The conversion efficiency of the X-ray detector has a critical impact on the performance and sensitivity of the X-ray instrument. Therefore, X-ray detectors have always been one of the breakthrough directions of X-ray instrument researchers.
Perovskite single crystals based on organic-inorganic hybrids have excellent carrier transmission properties, photoelectric conversion efficiency, and high absorption coefficients for X-rays. They are very suitable as semiconductor active materials in X-ray detectors. The research focus of the detector. However, due to the influence of factors such as device structure and manufacturing process, the perovskite single crystal will have problems of large dark state current and difficulty in suppressing noise after being applied to the X-ray detector.
In order to solve the deficiency of organic-inorganic hybrid perovskite single crystals as semiconductor active materials for X-ray detectors, the research team led by Professor Lei Wei of Southeast University prepared perovskite with concentration gradient characteristics based on solution epitaxial growth The cascade crystal X-ray photodiode uses the epitaxial process to solve the problems existing in the interface of the solution method device.
With the help of scanning electron microscopy and transmission electron microscopy, the research team used perovskite single crystals composed of different halogens with lattice constant mismatch rate less than 0.5% as intrinsic layers, N-type layers and P-type layers. The N-type layer, the intrinsic layer, and the P-type layer are epitaxially grown from the bottom up to obtain a cascade-type perovskite single crystal with excellent interface performance, and a low-noise, low-dose and high-resolution X-ray detector is prepared.
The X-ray detectors prepared by the research have extremely high sensitivity and fast response speed for medical high-energy X-rays of 100-140 keV, and low-dose chest CT and brain CT detectors have important reference significance. The idea of ​​improving the preparation method of perovskite single crystal by epitaxy based on the solution method can also be applied to the research and development of semiconductor devices in the field of high-energy ray detection.
Source: X-MOL