High-Density Inas/Gaas1-Xsbx Quantum-Dot Structures Grown By Molecular Beam Epitaxy For Use In Intermediate Band Solar Cells

InAs quantum-dot structures were grown using a GaAs1-xSbx matrix on a GaAs(001) substrate. The use of GaAs1-xSbx for the buffer and cap layers effectively suppressed coalescence between dots and significantly increased the dot density. The highest density (similar to 3.5 x 10(11)/cm(2)) was obtained for a nominal 3.0 monolayer deposition of InAs with an Sb composition of x = 13-14% in the GaAs1-xSbx matrix. When the Sb composition was increased to 18%, the resulting large photoluminescent red shift (similar to 90 meV) indicated the release of compressive strain inside the quantum dots. For x > 13%, we observed a significant decrease in photoluminescence intensity and an increase in the carrier lifetime (>= 4.0 ns). This is attributed to the type-II band alignment between the quantum dots and matrix material. (C) 2016 AIP Publishing LLC.