Aligned In0.5Ga0.5As quantum dots on laser patterned GaAs substrate

Abstract

It has been studied the selective InGaAs quantum dots growth on laser-patterned GaAs substrate by atmospheric pressure metal organic chemical vapor deposition (APMOCVD). We have patterned the samples below etching threshold power density 8.84 MW/cm(2) by argon ion laser (514 nm). The depth and lateral size of the pattern are about 8 nm and 100 nm, respectively. The QDs (quantum dots) were grown on AlGaAs matrix. The formation of QDs on the matrix can be obtained a wider energy gap between the states of QDs and the matrix materials than on GaAs matrix. The buffer layer consisted of a 0.6 um AlGaAs matrix layer and a 0.4 um GaAs layer. AlAs mole fraction of AlxGa1-xAs to realize graded refractive index is varied from 0.05 to 0.35. Structural and optical properties of InGaAs QDs were studied by scanning electron microscope (SEM), atomic force microscopy (AFM), and photoluminescence (PL). The QDs have a lateral size of about 20 nm and density of 3x10(10) cm(-2). Density and uniformity of QDs obtained on AlGaAs matrix are superior to on GaAs matrix. The PL peak of aligned InGaAs QDs is observed in the 900 nm.