Optical
transmission of IR radiation by coarse-grained Ge:Na plates is the same as in
Ge:Na
single crystals
and is higher than in Ge:Sb crystals
High optical
transmission of crystalline Ge:Na is due to the absence of impurity clouds that
could scatter the incident IR radiation
The advantages
of polycrystalline Ge:Na as a material of IR optics have been confirmed in the
process of its industrial application
Semiconductor Physics, Quantum Electronics & Optoelectronics, 21 (2), P. 173-179 (2018).
DOI: https://doi.org/10.15407/spqeo21.02.173
Large polycrystalline optical germanium Ge:Na plates with improved
optical parameters and their application
G.S. Pekar1, A.F. Singaevsky1, M.M. Lokshin1, V.I. Gordienko2, I.V. Mazurin2
1V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine,
41, prospect Nauky, 03680 Kyiv, Ukraine,
E-mail: pekar@isp.kiev.ua, 511alexsin@gmail.com
2State Enterprise Research & Production Complex “Photoprylad”,
85, B. Vyshnevetskoho str., 18001 Cherkasy, Ukraine
Abstract. It has been experimentally shown that transmission and scattering of IR radiation by Na-doped соarse-grained large germanium plates are the same as of Ge:Na single crystals and exceeds the parameters in the commonly used optical germanium Ge:Sb grown from the same raw material. Being based on experimental results, a conclusion has been made that the nature of the dopant in Ge:Na is a decisive factor defining its optical parameters, along with the usual requirements of high purity of the raw material, resistance values below about 20 Ohm·cm and a sufficiently large grain size (for polycrystalline material). It is assumed that, most likely, Na in Ge:Na, contrary to Sb in Ge:Sb, doesn’t form impurity clouds that scatter the incident IR radiation. The advantages of the polycrystalline Ge:Na as a material for IR optics were proved when using it for industrial manufacturing the protective screens for night vision systems.
Keywords: Na-doped germanium, large coarse-grained plates, optical transmission, protective screens, thermal imaging systems.
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