ANOMALIES IN PHOTOLUMINESCENCE LINEWIDTH OF INGAAS/GAAS STRAINED-LAYER QUANTUM-WELLS

Anomalous temperature dependences of photoluminescence (PL) linewidth were found in InxGa1-xAs/GaAs strained-layer quantum wells (QW's). The PL linewidth exhibited two different types of anomalous behavior depending on the well width L(z) and the indium composition x. With increasing temperature, (i) QW's with L(z) exceeding the critical layer thickness exhibited a linear increase followed by an abrupt decrease of the linewidth, whereas (ii) QW's with x greater-than-or-equal-to 0.144 and L(z) almost-equal-to 50-70 angstrom showed linewidth narrowing. We explain these phenomena as due to (i) competition between free excitonic and dislocation-related emissions and (ii) exciton localization due to alloy disorder, respectively. By taking account of these anomalous behaviors, the dependence of the PL linewidth on L(z) was satisfactorily explained in terms of alloy disorder.