Effect of growth temperature on photoluminescence of self-assembled Ge(Si) islands confined between strained Si layers

The effect of growth temperature on photoluminescence is studied for structures with Ge(Si) islands grown on relaxed SiGe/Si(001) buffer layers and confined between strained Si layers. It is shown that, with decreasing growth temperature in the range from 700 to 630 deg. C, the photoluminescence peak associated with the islands shifts to lower energies, which is due to the increase in Ge content in the islands and to suppression of degradation of the strained Si layers. The experimentally observed shift of the photoluminescence peak to higher energies with decreasing temperature from 630 to 600 deg. C is attributed to the change in the type of the islands from domelike to hutlike in this temperature range. This change is accompanied by an abrupt decrease in the average height of the islands. The larger width of the photoluminescence peak produced by the hut islands in comparison with the width of the peak produced by the domelike islands is interpreted as a result of a wider size dispersion of the hutlike islands