Stacking growth of in-plane InAs quantum-dot superlattices on GaAsSb/GaAs(001) for solar cell applications

Self-assembled InAs quantum dots(QDs) were grown on GaAsSb/GaAs(001) layer by solid-source molecular beam epitaxy (MBE) using Stranski-Krastanov (SK) mode. High dot density of about 4 × 10¹¹ cm^-2 was demonstrated on the GaAsSb/GaAs buffer layer. In spite of high dot density, coalescence of neighboring dots was effectively suppressed on the GaAsSb surface. PL spectra shifted toward high energy side, as the excitation power increased high energy side. It suggests that these ultra-high density QDs form in-plane QD superlattice structure. The Sb-mediated growth method is a promising way to fabricate ultra-high density QD structures on the GaAs(001) substrates for solar cell applications.