Melting Threshold and Thermal Conductivity of CdTe Under Pulsed Laser Irradiation
The paper is devoted to the study of the features of CdTe surface treatment under laser irradiation with both different wavelengths (λ = 300–800 nm) and pulse durations (τp = 7 ns–1 ms). The thermal conductivity of the semi-insulating p-like CdTe semiconductor crystals was evaluated using the photoacoustic gas-microphone method. Simulations of the melting threshold were performed based on the three stage model of the laser induced excitation and relaxation. In particular, the following processes were considered in frames of the model: (i) rapid interband thermalization, (ii) nonradiative interband and (iii) nonradiative surface recombination. It was revealed that in the range of pulse durations from 7 ns to 1 μs, the melting threshold of the CdTe mainly depended on the absorption coefficient α(λ). For pulse durations longer than 1 μs the threshold started to depend also on the spectra of the reflectivity coefficient R(λ). The obtained results have been used for optimization of the laser-assisted techniques of surface processing and stimulated doping of CdTe crystals.
KeywordsCdTe Melting threshold Photoacoustic method Pulsed laser irradiation
This research was supported by the following research projects: “Laser pulsed photothermoacoustic formation of CdTe-based sensor structures with super-high resolution for radiation monitoring systems” (State Fund For Fundamental Research of Ukraine, grant number F85), “Features of photothermal and photoacoustic processes in low-dimensional silicon-based semiconductor systems” (Program of the Ministry of Education and Science of Ukraine, state registration number 0118U000242), “Development of Cd(Zn)Te-based X/gamma-ray detectors with high resolution for security and diagnostics instruments” (The 2019 Cooperative Research at Research Center of Biomedical Engineering, Japan, grant number 2022), “Development of perovskite single crystal X/gamma-ray detectors for environmental radioactive contamination monitoring” (The Short-term Recruitment Program of Foreign Experts in Anhui (APFEP, 2019, China), “Exploring novel perovskite single-crystal based gamma-ray detector for trace environmental radioactivity monitoring” (Program of the Joint Ukraine - The People’s Republic of China R&D Projects for the period of 2019–2020 adopted by the Ministry of Science and Technology of the People’s Republic of China, grant number CU03-15).
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