PHOTO- AND ELECTROLUMINESCENCE IN ZINC GERMANATE AND ZINC SILICATE POWDERS AND ACTFEL DEVICES

摘要

Manganese-doped zinc germanate and silicate powders exhibit bright green photoluminescence with excellent chromaticity, affording a variety of applications in displays and lighting. Typical preparative methods include high temperature solid-state reactions between the appropriate starting materials. These temperatures can exceed 1273 K. Likewise, thin-film methods require annealing of the as-deposited films at temperatures above 873 K. In this contribution, we describe a new, low-cost and easy way to make zinc germanate and zinc silicate powders and films at temperatures as low as 398 K. Zinc silicate has been prepared by both low- and high-temperature methods. Precipitation reactions can be carried out to form a hydroxylated species. Dehydration of this product in air at 473 K leads to the production of an amorphous product. If, however, the precipitate is placed in a Teflon-lined high-pressure reaction vessel at 473 K for a period of 12 h, a highly crystalline product is formed. Since as-deposited, sputtered films of zinc germanate are amorphous, high temperature anneals are generally required in order to produce a crystalline material. Depending on the method used, annealing temperatures of 873 to 1073 K are usually employed. The hydrothermal anneal described above can be used to produce a crystalline thin-film of zinc germanate at temperatures as low as 398 K.