Thickness dependence of exciton and polariton spectra from ZnSe films grown on GaAs substrates

Abstract

of in-plane strain anisotropy in ZnSe(001)/GaAs layers using reflectance difference spectroscopy J.ZnSe films with thicknesses from 0.05 to 1.45 m were grown on GaAs substrates by molecular beam epitaxy. Low temperature photoluminescence ͑PL͒ and reflectance spectra are presented to show the thickness dependence of the exciton and polariton properties in the films. In addition to sharp PL peaks from free and donor bound excitons, an acceptor bound exciton peak was observed in the thin films and its intensity decreases rapidly with the film thickness. The PL characteristics show the acceptor centers being the defect states near the ZnSe/GaAs interface. The classical theory of exciton-polaritons was used to calculate the reflectance spectra and compared to the measured results. The comparison reveals the effects of strain, surface, and interface on the reflectance spectra from both heavy-and light-hole excitons. In addition to the strain-induced light-and heavy-hole splitting, the light-hole excitons show a larger damping and less sensitivity to the surface dead layer than the heavy-hole excitons. When the film thickness increases, the interference effects become more important and the contribution from the excited exciton states to the reflectance spectra may no longer be negligible.

Excitons in a GaAs Film on AlxGa1-xAs Influenced by the Thickness of the Substrate

“…Optical spectroscopy of large-momentum excitons in GaAs films was experimentally and theoretically investigated by some authors [2,3]. Photoluminescence (PL) spectrum measurements was used to treat exciton [4,5] and excitonpolaritons [6] problems and to determine the exciton binding energy [7,8] in various semiconductor films such as CdS, ZnSe, GaN and CsSnI 3 films. In particular, the GaAs film on Al x Ga 1−x As substrate is an important semiconductor low-dimensional structure.…”

Fractional-dimensional approach for excitons in GaAs films on Al x Ga 1− x As substrates

“…[2] The optical spectroscopy of large-momentum excitons in GaAs films was experimentally and theoretically investigated by some researchers. [3,4] Photoluminescence (PL) spectrum measurements were used to study exciton [5,6] and exciton-polariton [7] problems and to determine the exciton binding energies [8,9] in various semiconductor films, such as CdS, ZnSe, GaN, and CsSnI 3 films. In particular, the GaAs film on Al x Ga 1−x As substrate is an important semiconductor low-dimensional structure.…”

First principles studies of band structure and electronic properties of ZnSe

“…ZnSe (zincblende) is a II-VI semiconductor compound with a band gap of 2.70 eV [6]. Hence, it has played a prominent role in optoelectronic devices specifically, in the blue green region of the electromagnetic spectrum [7][8][9][10][11]. The electronic, transport and magnetic properties of the semiconductor compound have generated more interest in recent time due to the application of the compound in sprintonic [1].…”