Method of manufacturing light absorbing layer for solar cell using selenization process under element selenium vapor ambience and thermal treatment apparatus for manufacturing light absorbing layer

A method of manufacturing a light absorbing layer for a solar cell by performing thermal treatment on a specimen configured to include thin films of at least one or more of copper, indium, and gallium on a substrate and a source material including element selenium, comprising steps of:

• (a) heating wall of a chamber up to a pre-defined thin film formation temperature;
• (b) mounting a source material including the element selenium and the specimen on a susceptor at the room temperature and loading the susceptor on which the source material and the specimen are mounted in the chamber of which wall is heated;
• and
• (c) while controlling a temperature of the source material including the element selenium inserted into the chamber and a temperature of the specimen, performing thermal treatment on the specimen and the element selenium on the susceptor up to the thin film formation temperature,
• wherein, in the step (c), during the thermal treatment, the temperature of the element selenium and the temperature of the specimen are individually controlled so that the selenium is not condensed on the specimen.