Photoluminescence study of CdTe/ZnTe self-assembled quantum dots

Abstract

We report on optical properties of CdTe self-assembled quantum dots ͑SADs͒ grown by molecular beam epitaxy on ZnTe. Formation of SADs was achieved by deposition of 1.5-2.5 monolayers of CdTe at a substrate temperature of 420°C and by applying growth interrupts for few seconds in Cd flux. The resulting dots have a typical diameter of 2 nm and a sheet density of 10 12 cm Ϫ2 . At Tϭ2 K the photoluminescence ͑PL͒ spectra consist of two emission lines. The high-energy line originates from excitonic recombination in a wetting layer while the low-energy emission PL band is assigned to recombination in SADs. The increase in temperature up to 70 K does not affect the SADs-related emission intensity. It shifts, however, the PL peak energy towards low energies and causes a significant narrowing of the PL linewidth, from 80 meV at 1.9 K to 50 meV at 130 K. The activation energy of the thermal quenching of SADs-related PL emission was found to be equal to 47 meV. This value is three times greater than the one observed in CdTe/ZnTe quantum wells, that is, 12-17 meV.

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

“…2.2-(b)) within the same temperature region where the peak position exhibits a red shift relative to the bandgap ( Fig. 2-(c)); this means that one is dealing with an ensemble of such low dimensional structures (Brusaferri et al, 1996;Sanguinetti et al, 1999;Karczewski et al, 1999). It is more important that the careful analysis of the green band peak position at various excitation intensities showed that it increases linearly with the cubic root of excitation intensity (the lower inset in Fig.…”

Excitation Mechanisms of CdTe/ZnTe Quantum Dots under Non-Resonant and Quasi-Resonant Regime

“…Two sam- * corresponding author; e-mail: Tomasz.Kazimierczuk@fuw.edu.pl ple growth procedures were used. The first studies on non-resonant excitation mechanisms were performed on dots formed with growth-interrupt method [6]. More advanced experiments under non-resonant and quasi--resonant regime were done on dots grown with amorphous tellurium technique described in Ref.…”

Coupling of Quantum Dots with Quantum Wells in a System Based on (Cd,Zn,Mg)Te

“…In particular, in telluride systems, good optical properties can be obtained for CdTe QWs embedded in (Cd,Mg)Te barriers, and CdTe QDs in ZnTe barriers. However emission energy of such QWs is about 1.6 eV [18], and about 2 eV for QDs [19]. Moreover ZnTe barrier exhibit much smaller lattice parameter than CdTe or (Cd,Mg)Te.…”