Optical properties of CdTe quantum dots

P. Wojnar ,  Marta Aleszkiewicz ,  Jacek Kossut ,  Grzegorz Karczewski 

Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland

Abstract

We investigated electroluminescence (EL), photoluminescence (PL) and micro-photoluminescence (μ-PL) of self assembled CdTe quantum dots (QDs) embedded in different II-VI materials: ZnCdTe, ZnMgTe and CdMgTe. Our structures were grown by Molecular Beam Epitaxy (MBE) employing a new self formation method of the QDs proposed recently by Tinjod et al. [1]. The most important advantage of this method is the possibility of quantum dots formation even when the lattice mismatch between the dot and the barrier material is as small as 2.8%. Another advantage is the possibility of in-situ observation of the 2D-3D transition by RHEED (Reflection of High Energy Electron Diffraction).
The surface of our structures was examined by Atomic Force Microscopy. From these measurements, we obtained the density of dots of the order of 1010 cm-2, the average in-plane diameter and the average height being about 30nm and 7nm, respectively.
For EL measurements we have introduced CdTe quantum dots layer into a p-n junction. We have chosen carefully the n-type and p-type materials taking into account their electrical and optical properties. The quality of p-n junctions was characterized by current-voltage measurements. We have studied temperature and voltage dependencies of the luminescence.
The typical PL and EL spectra of a quantum dots layer consist of a very broad line. Its spectral width is determined by inhomogeneity of the sizes and chemical compositions of the quantum dots in the ensemble. In the case of μ-PL, we decrease the diameter of the excitation spot down to 2 μm. The PL line splits into a large number of sharp spikes with the spectral width in range of 100 μeV. The narrow lines are attributed to individual quantum dots. We found that we can significantly shift the position of the luminescence line, when we change the composition of the barrier, from 1.7eV to 2.3eV.
[1] Tinjod F., Gilles B., Moehl S., Kheng K., Mariette H. Appl.Phys.Let.,v 82, 24, p.4340
[
[ABSTRACT TRUNCATED TO 2000 LETTERS]

Related papers
  1. Diluted magnetic semiconductors – from bulk crystals to low dimensional structures
  2. Neutron scattering studies of short-period MnTe/ZnTe superlattices: magnetic order, magnon propagation and confinement
  3. Transparent p-type ZnO obtained by Ag doping
  4. Raman spectroscopy of ZnTe-based nanowires grown by MBE *
  5. Resonant and non-resonant Raman spectra of CdTe/ZnTe self-assembled quantum dots
  6. Catalytic growth by molecular beam epitaxy and properties of ZnTe-based semiconductor nanowires
  7. MBE Growth and Optical Study of Magnetic CdMnTe Quantum Dots
  8. Time-resolved ODMR investigations of II-VI based DMS heterostructures
  9. Optical properties of p-type ZnO:(N, As, Sb)
  10. Optical and magnetooptical properties of the p-type ZnMnO.
  11. Periodic boundary conditions in micromagnetic modeling
  12. Magnetic stripe domains in Fe/Fe-N multilayers
  13. Quantitative study of Cd atoms distribution in CdTe/ZnTe quantum dots superlattice by HRTEM
  14. Preparation and characterization of hexagonal MnTe and ZnO layers
  15. p-type conducting ZnO: fabrication and characterisation
  16. Fabrication and characterization of II-VI diluted magnetic p-n junctions
  17. Folded Acoustic phonons in (CdTe)n/(MnTe)m superlattices
  18. Area detector as a tool to study properties of the magnetic multilayers by the neutron scattering
  19. Influence of hydrogen adsorption on magnetic properties of Fe films and multilayers
  20. Structure characterisation of MBE-grown ZnSe:Cr layers
  21. Medium scale modeling of the CdTe/ZnTe islands the empirical potential and finite element approach

Presentation: oral at E-MRS Fall Meeting 2004, Symposium F, by Piotr Wojnar
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-05-20 15:17
Revised:   2009-06-08 12:55
Google
 
Web science24.com
© 1998-2018 pielaszek research, all rights reserved Powered by the Conference Engine