Parametric study on optical properties of digital-alloy In(Ga1-zAlz)As/InP grown by molecular-beam epitaxy

Abstract

Optical properties of digital-alloy InGaAlAs grown by molecular-beam epitaxy were parametrically investigated by 10-K-photoluminescence (PL) study on (In0.53Ga0.47As)(n)/(In0.52Al0.48As)(n) short-period superlattices (SPSs) in the range of n=1-5 monolayers. Two different peaks are resolved in PL spectra, and the higher energy peak (H) results from an excitonic transition while the lower energy peak (L) is related to a phonon-assisted transition. The H peak energies decrease monotonously as n increases, and it is in good agreement with the band-gap calculation with transfer matrix methods. It is found that two monolayer-period length (n=2) is the optimum one, where the PL intensity is largest and the ratio of L peak to H peak intensity is lowest. The various compositions (z) of digital-alloy In(Ga1-zAlz)As are prepared and their optical properties are investigated for z=0.2, 0.4, 0.6, and 0.8. The linewidths of 9-K-PL spectra for various z values are within the range of 10-15 meV, which are comparable to the best analog-alloy InGaAlAs. (C) 2004 American Institute of Physics.