THE EFFECT OF PRESSURE ON THE OPTICAL-ABSORPTION EDGE IN (GA0.3IN0.7)2SE3

The influence of hydrostatic pressure (up to 0.4 GPa) on optical trans itions of (Ga0.3In0.7)2Se3 in the long-wave end of the fundamental abs orption edge is studied at 296 K. The application of higher pressure c auses an increase of the indirect optical energy gap as well as a high er transparency in the near-edge region, the emergence of a step-like structure in the absorption spectrum due to the formation and decay of free excitons, and the increase of steepness parameter sigma of the U rbach tail in the exponential region. All these changes are interprete d as a result of diminished disorder in the crystals.