Hydrogen in optical germanium and reduction of its negative impact on the crystal properties by ultrasonic processing

Abstract

Hydrogen content and its effect on the properties of optical germanium has been first investigated. Large coarse-grained plates of Na-doped optical germanium, grown in an inert atmosphere, are shown to contain dissolved hydrogen in a concentration about 1.9 × 1017 cm− 3. It is shown that the presence of hydrogen can lead to the porosity of the plates, to the plate cracking and to the release of toxic gases during plate machining, as well as to some other negative effects. A technique for ultrasonic plate processing has been developed, which leads to a decrease in the hydrogen content by about 7 times, to an increase in the mechanical strength of the plates, to an increase in the material density, to a decrease in the Ge lattice parameter, and ultimately to eliminating all listed negative effects caused by the presence of hydrogen. The developed method of plate processing has found a successful application in the industrial production of protective screens for thermal imaging systems of night vision based on optical germanium plates.