The Influence of Growth Temperature on InAs/GaAs Quantum Dots

For InAs quantum dots (QDs) grown on GaAs by molecular-beam epitaxy (MBE), we demonstrate the surface morphology and optical characteristics of dots formed under different growth temperatures of 480, 500, 520 °C. From the atomic force microscopy (AFM) results, all sample exhibited two-group size distributions which are attributed to the QDs coalescence resulting from the slow cooling procedure after quantum-dot growth (~15 °C/min.). Simultaneously, the decrease of dots density with increasing growth temperature is attributed to the enhancement of In adatom migration length at higher growth temperature. The observation of higher-order excited state luminescence for QDs grown at 500 °C has indicated a high carrier lifetime for the photo-excited electrons. From PL results of sample B, 500 °C is the optimum growth temperature for InAs/GaAs QDs.