Optical studies of InAs/GaAs on GaAs short-period strained-layer superlattices grown by MBE and MEE

Abstract

We have grown InAs/GaAs short-period strained-layer superlattices (SPSLSs) by both conventional molecular beam epitaxy (MBE) and migration enhanced epitaxy (MEE). Our efforts have been directed towards the optimization of growth parameters including shutter times, growth interrupt times, and substrate temperatures for both growth techniques. We have investigated several structures with different numbers and thicknesses of InAs and GaAs layers. Optical measurements, including absorbance, CW photoluminescence (PL), and time resolved PL, have been employed to determine the quality of the samples. We have grown samples with 50 repetitions of the SPSLS separated by 20 nm GaAs barrier layers which have exhibited excellent 5 K CW PL peaks with full width at half maximum (FWHM) of less than 9 meV. In addition, several samples have shown room temperature exciton features in absorbance spectra. A synchronously mode-locked Styryl 9 dye laser has been used in conjunction with a streak camera to perform time resolved PL measurements, thereby determining carrier lifetimes in the samples. We will discuss our results, comparing the growth conditions as well as the different SPSLS structures, in terms of the optical data that we have obtained.