Linewidth broadening of quantum dot emission caused by temperature fluctuations

The temperature dependence of the homogeneous linewidth of optical transiti ons in a single semiconductor quantum dot (QD) due to temperature fluctuati ons is calculated. Since the temperature fluctuations are inversely proport ional to the considered volume and the QD volume is very small, the tempera ture of a QD and therefore its energy states are not well defined. Therefor e, the emission and absorption spectra are homogeneously broadened. The bro adening is calculated for simplified cuboid-like electron and hole wavefunc tions assuming spatially constant material parameters. The linewidth is str ongly dependent on temperature and volume of the QD, whereas the shape of t he wavefunction is less important. For cubic In0.5Ga0.5As QDs with volume ( 5 nm)(3), the broadening is similar to 10 mu eV below 100 K and reaches sim ilar to1.4 meV at room temperature.