OBTAINING METHOD OF CRITICAL FILM THICKNESS OF COMPOUND SEMICONDUCTOR LAYER AND MANUFACTURE OF OPTICAL SEMICONDUCTOR DEVICE WHICH USES THE METHOD

摘要

PURPOSE: To provide a method for obtaining the crytical film thickness of an active layer or the like of an optical semiconductor device composed of a II-VI compound semiconductor layer, and form the optical semiconductor device under the optimum condition. CONSTITUTION: The relation between the film thickness of a compound semiconductor layer and the PL intensity is obtained by observing photoluminescence(PL) of the compound semiconductor layer which PL corresponds with the film thickness. The film thickness wherein the PL intensity forms a peak IP is obtained as the critical film thickness hPL. A relational equation for approximating the critical film thickness by setting the composition ratio of cadmium(Cd) in the compound semiconductor layer as a function is obtained. By using the relational equation, the critical film thickness of the compound semiconductor layer having a desired Cd composition ratio is obtained. The film thickness of the active layer is designed to be less than or equal to the critical film thickness obtained in the above manner. The active layer is formed to have the film thickness designed when a II-VI compound semiconductor layer containing an active layer is deposited on a substrate, and an optical semiconductor device is formed.