6LiInSe2 is a promising semiconductor candidate for thermal neutron detection due to its large capture cross-section. However, the charge collection efficiency is still insufficient for high resolution for the grown-in defects induced by the stoichiometric deviation. In this work, we report photoelectric properties of stoichiometric LiInSe2 crystal boules up to 70 mm in length and 20 mm in diameter grown by the vertical Bridgman method. Inductively coupled plasma measurements demonstrate that the ratio of Li, In, and Se of the as-grown crystal is very close to 1:1:2, which is optimized by low temperature synthesis processing. The obtained single crystals display high bulk resistivity in the range of 1011–1012 Ω·cm and a direct band gap of 2.01–2.83 eV with a changeable color from red to yellow. The electronic structure of LiInSe2 was studied using first-principles density functional theory calculations, which predicts that the antisite defects of InLi and LiIn are the dominant factor for the different crystal colors observed. The stoichiometric LiInSe2 crystal gives an improved energy resolution, for a semiconductor detector when illuminated with a 241Am@5.48 MeV α source, of 23.3%. The electron mobility-lifetime product (μτ) is ∼2.5 × 10–5 cm2 V–1.

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As located in the focal plane of the imaging system, the image sensor will be easily influenced by the huge optical gain, which is brought in the image sensor by the external optical system and microlens on the surface of the device. Laser has a great influence on the image sensor, which is a sensitive link of the anti-laser reinforcement of the imaging system. Improving the performance in extreme light conditions in order to study the vulnerability of image has an important significance of reinforcement. As a typical visible light image sensor, which has advantages of sensitivity, high dynamic, small, light and so on, IT-CCD has been widely used in the fields of reconnaissance, detection and military. An 800nm femtosecond pulse laser was used to carry out experimental research on the laser irradiation effect of IT-CCD. The results shown that the local pixel of IT-CCD was in a state between undamaged and the white point damaged after irradiating by the laser, which was named by gray point. It was shown that the influenced pixels of IT CCD were changed by the laser, but no obvious deformation occurred. Through microscopic detection and analysis, the damage mechanism was expounded, further analysis was done. With focus ion beam (FIB) technique, it was found that there was photosensitive potential well, micro-structure of SiNx filling layer under microlens of the IT-CCD. When the gray point damage occurred, neither the photosensitive potential well at the bottom of the device was damaged, nor was the microlens structure on the surface. It turned out that the SiNx filling layer was influenced by the laser. Through elucidating the mechanism of this damage of the gray point, it lays a foundation for damage mechanism research.

Germanium is widely used as lens or windows in infrared optical systems, however, germanium optical elements may be damaged by melting under high energy laser irradiation. Therefore, it is necessary to carry out theoretical and experiment research on laser damage threshold of the germanium optical material. In this paper, the effect of laser beam diameter on the damage threshold of germanium was analyzed by numerical calculation. Besides, the difference of damage threshold represented using line power density and area power density was compared. It was found that when the diameter ratio of beam spot to sample was 0.02 to 0.09, the damage threshold decreased by 27.9% and 85.6%, respectively, when using W/cm and W/cm2 as the unit correspondingly. Considering the difference between the size of the beam and the element in optical system, the line power density is more suitable for extrapolation and comparison. In addition, the numerical results were verified by damage threshold experiment under the continuous laser of 1080 nm, which indicates the damage threshold of germanium is 263W/cm, 280W/cm and 290W/cm respectively, and the beam diameter is 0.5mm, 1mm and 2mm correspondingly. It was found that when the diameter ratio of beam spot to sample was 0.021 to 0.083, the damage threshold increased by 10.3% and decreased by 85.6%, respectively, when using W/cm and W/cm2 as the unit correspondingly. These results provide data support for the design and application of germanium optical elements to ensure the reliability of the high energy laser system.