Optical Characterization of InAs/GaAs1-xSbx Quantum-Dot Structures

InAs quantum-dot structure were grown on GaAs (001) substrate using GaAs1-xSbx matrix. The use of GaAs1-xSbx for the buffer and cap layers could suppress coalescence between dots effectively and increase the dot density significantly. Also, InAs/GaAs1-xSbx QDs show a band alignment transition from type-Ⅰ to type-Ⅱ as the Sb concentration increases. In this work, the quantum-dot structure has been studied using power-dependent photoluminescence to determine the band structure. At low Sb concentration (Sb<13%), InAs/GaAs1-xSbx maintain the type-Ⅰ alignment. At high Sb concentration (Sb>13%), InAs/GaAs1-xSbx demonstrate a type-Ⅱ band structure. Time-resolved photoluminescence measurement is performed to study carrier dynamics in the quantum-dot structure at 7K to understand the type-Ⅰ and type-Ⅱ transition in more detail