Growing optical Ge plates with an improved high-yield method of horizontal directed crystallization

Abstract

This paper aims to disseminate an improved technique of horizontal directed crystallization (HDC) which allows several polycrystalline or single-crystalline plates to grow in each growth process. This technique is more productive and cost-effective than the usual HDC method which allows only one plate to grow. The plates are grown under the same process conditions, and if necessary, they can be doped at the same or different impurity concentrations. The main feature of the technique developed is that the growth container is made of a heat-resistant material, for example, graphite, and has several cavities (chambers) for the raw material, sequentially located along the length of the container. For growing single-crystalline plates, all the chambers are interconnected by thin channels. We have applied this technique for growing Na-doped optical germanium plates with an area of up to 400 cm² used for the industrial manufacturing of protective screens for thermal imaging systems used for night vision.