Lviv Polytechnic National University
Lviv Polytechnic National University
Lviv Polytechnic National University
Lviv Polytechnic National University
Lviv Polytechnic National University

The zinc sulfide (ZnS) and zinc selenide (ZnSe) films of belongs to the AIIBVI group of semiconductors type, which are the main part of photosensitive elements of electronic devices. An analytical review of the scientific and technical literature shows that in recent years intensive research has been conducted to replace toxic cadmium-containing films with non-toxic counterparts, while maintaining the effectiveness of photovoltaic elements. The ZnS and ZnSe films are the most promising for this replacement. This means that the production of ZnS and ZnSe solid semiconductor films with a simple and reproducible method that must satisfy the economic and environmental aspects of production and provide high quality material is an important and actual scientific task.

In recent years, the ZnS and ZnSe films are obtained by methods that are based on physical or chemical processes. The first ones include electron-beam deposition, molecular beam epitaxy, impulse laser deposition, and radio frequency magnetron sputtering. To the latter – electrochemical deposition, sol-gel deposition, chemical deposition from the gas phase, sequential ion-layer adsorption with reaction and chemical deposition. The obtaining conditions and properties of zinc chalcogenide films, synthesized by various methods, are summarized in one table.

Physical methods are quite energy-intensive, require the use of high temperature, often vacuum, expensive equipment. The crystal structure of the films is predominantly cubic. This can be explained by the fact that they are obtained from powders of ready compounds of zinc chalcogenides, which have the same structure. The energy for the complete phase transformation to hexagonal phase is small. Chemical methods are simpler, cheaper, less energy consumer than physical. They do not require the use of expensive equipment. The exception is chemical vapor deposition. The films obtained by these methods are not inferior of their characteristics to those obtained by physical methods. The crystalline structure of the films can occur of both cubic and hexagonal or their mixture, because, unlike physical methods, the zinc chalcogenide compound is obtained on a substrate from initial reagents containing zinc and chalcogen, while passing a chemical reaction between them.

The method of chemical deposition is noted as the optimal for the obtaining of ZnS and ZnSe films. It is ideal for the manufacture of thin films on large areas of substrates. Synthesis of coatings takes place at temperatures below 100 °C and atmospheric pressure. By describing the chemical deposition method, the chemistry of the formation process of slightly soluble compounds of ZnS and ZnSe is given.

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