Formation and optical properties of CdTe∕ZnTe nanostructures with different CdTe thicknesses grown on Si (100) substrates

Abstract

Atomic force microscopy (AFM) and photoluminescence (PL) measurements were carried out to investigate the formation and the optical properties of CdTe∕ZnTe nanostructures with various CdTe thicknesses grown on Si (100) substrates by using molecular beam epitaxy and atomic layer epitaxy. AFM images showed that uniform CdTe∕ZnTe quantum dots with a CdTe layer thickness of 2.5 ML (monolayer) were formed on Si (100) substrates. The excitonic peaks corresponding to transitions from the ground electronic subband to the ground heavy-hole band in the CdTe∕ZnTe nanostructures shifted to a lower energy with increasing thickness of the CdTe layer. The activation energies of the carriers confined in the CdTe∕ZnTe nanostructures grown on Si (100) substrates were obtained from the temperature-dependent PL spectra. The present observations can help improve understanding of the formation and the optical properties in CdTe∕ZnTe nanostructures with different CdTe thicknesses grown on Si (100) substrates.

Exciton quantum confinement in nanocones formed on a surface of CdZnTe solid solution by laser radiation

“…The calculation of the quantum dot diameter using formula from [ 25 ] and the blue shift of A 0 XQC in the PL spectrum of 0.27 eV gives about 10.0 nm diameter of the quantum dots. These data correspond to the size of nanocones [ 26 ] (height and diameter of the bottom of the cones are 10.0 nm) measured using 3D image of AFM as can be seen in Figure 1 . An evidence of the presence of EQC in nanocones is the decrease of LO phonon energy by 0.7 meV in the PL spectrum.…”

Carrier dynamics and activation energy of CdTe/ZnTe nanostructures with different CdTe thicknesses

“…The increase in the activation energy of the electrons confined in CdTe/ZnTe nanostructures with increasing CdTe thickness from 2.5 to 4.0 ML is related to an enhancement of the quantum confinement effect resulting from an increase in the energy difference between the electronic state and the conduction band edge [21]. The decrease in the activation energy of the electrons confined in CdTe/ZnTe nanostructures with increasing CdTe thickness from 4.0 to 4.5 ML is attributed to a decrease in the quantum confinement effect, resulting from the dimensional transition from QDs to QWRs [22].…”