HYDROTHERMAL GROWTH OF ZINC OXIDE CRYSTALS.

A pilot line for the production of large high quality ZnO single crystals was established and many large crystals were produced. The pilot line can be divided into two units, 1 a molten salt line for the production of seed plates to be used in 2 the hydrothermal crystal growth pilot line. The design and construction of both lines were successfully completed and functioned as planned. The molten salt crystal growth effort was not as successful as had been anticipated. Large area, high quality crystals could not be made reproducibly by this technique. The most apparent reasons for the failure to do so rests in thermal gradient control during the growth cycle andor the presence of impurities. Although these problems were not completely resolved the molten salt pilot line did yield sufficient plates for the initial portion of the hydrothermal pilot line, and hydrothermally grown crystals were sectioned and used as seeds for subsequent runs. The area of the crystals were increased by continued growth until large high quality crystals weighting more than 150 grams could be grown on such seeds within reasonable operating times.