Optical properties ofδ-doped ZnSe:Te grown by molecular beam epitaxy: The role of tellurium

Abstract

We have studied the optical properties of the ␦-doped ZnSe:Te system using photoluminescence ͑PL͒ and x-ray and Raman scattering. Two different types of sample were investigated, ͑1͒ with a single ␦ layer and ͑2͒ with three adjacent ␦ layers separated by undoped layers. All of these samples are of reasonable crystalline quality and have the symmetry of the host ZnSe lattice as determined by x-ray and Raman scattering. The PL from each sample is very similar to the PL from bulk Zn-Se-Te solutions at low Te concentrations. The PL from the single-␦-doped material shows emission relatively close to the band edge which we attribute partly to Te 2 clusters ͑nearest-neighbor pairs͒ and partly to non-nearest pairs. This PL changes with storage time, from which we conclude that the nearest-neighbor pairs are more stable than non-nearest-neighbor pairs. The triple-␦-doped material also shows a deeper PL feature, with a peak at about 2.48 eV, which we attribute to Te nу3 clusters as well as to corresponding non-nearest-neighbors pairs.

Time resolved photoluminescence studies of Zn–Se–Te nanostructures with sub‐monolayer quantities of Te grown by molecular beam epitaxy

“…We note that the cw PL of these type-II QIs shifts as a function of the excitation intensity [1] too, as expected for such systems [4]. For sample B, this type-II QI-related PL has a very weak intensity and appears only at the delay times larger than 10ns as a low-energy shoulder on the peak due to excitons bound to Te 2 isoelectronic centers [2]. Therefore, the shift of this type-II QI-related PL in sample B is more difficult to observe.…”

“…Recently it has been shown [1] that, in a so-called triple-delta-doped ZnSe:Te system (denoted further as δ 3 -ZnSe:Te, for growth details see Ref. [2]), there is formation of type-II quantum islands (QI), which contribute to photoluminescence (PL) with the maximum at ~2.46-2.51 eV ("green band"). In this paper, we investigate the effect of Te/Zn flux ratio used during the growth on such quantum structures using timeresolved photoluminescence (TRPL).…”

Non-equilibrium Approach to Doping of Wide Bandgap materials by Molecular Beam Epitaxy. Final Report

“…We show the PL spectra at various excitation intensities for a 63doped sample in Fig. 1 (see also Kuskovsky et al, 2001a). The spectra show two band at -2.65eV ("blue band") and 2.49eV ("green band").…”

“…The spectra show two band at -2.65eV ("blue band") and 2.49eV ("green band"). These had been, at the time, attributed by Kuskovsky et al (2001a) to isoelectronic excitons bound at centers consisting of several Te atoms. We note that one also observed a decrease of the full-width-athalf-maximum (FWHM) of the green band with temperature ( Fig.…”

“…In addition, we have also used it to characterize samples of ZnSe &doped with Te only (i.e. without N) as control samples (Kuskovsky et al, 2001a.…”