<title>Luminescence polarization anisotropy in (Al,Ga)As serpentine quantum wire arrays</title>

Abstract

Serpentine superlattices (SSL) with a parabolic-crescent cross section defining the wells and barriers, have been grown on vicinal GaAs substrates by molecular beam epitaxy. The SSL structures have been studied by photoluminescence (PL) and photoluminescence excitation (PLE) measurements at 1.4 K, showing a strong polarization anisotropy in both PL and PLE. The carrier confinement has been characterized by measuring the linear polarization dependence of the PL from the surface as well as from the cleaved edges by using a photoelastic modulation technique. Calculations of the conduction band and valence band electronic structure describe the polarization dependence as a function of segregation into lateral wells and barriers. We find that about 30% of the Al intended for the barriers end up in the well giving AlxGa1-xAs wells and barriers of x equals 0.12 and 0.21, instead of the nominally intended values of 0.00 and 0.33, corresponding to a lateral conduction band barrier of 70 meV. Linear polarized PLE has been used to reveal the laterally induced heavy-light hole splitting. PL decay time measurements of the serpentine emission, shows a longer decay time than for a reference alloy-well structure, indicating a reduced carrier relaxation in the serpentine structure. The linear polarization of the PL is found to be rather constant over large areas of the wafer indicating uniform quantum wire like states, showing the intended advantage of the serpentine structure over tilted superlattices.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.