Free‐exciton absorption in bulk CdTe: temperature dependence

Self Cite

In this paper we report on the measurements of the dephasing of free carriers and excitons using a selfdiffraction technique in thin platelets of CdTe with different concentration of preparation-induced dislocations. We show that in a high-quality sample at low temperature the characteristic dephasing time constant is 1 ps and 2 ps for free carriers and excitons, respectively. The increased concentration of preparationinduced dislocations leads to much stronger acceleration of the dephasing for free carriers than for excitons. We also discuss the intensity and temperature dependence of the dephasing.

Section: Resultsmentioning

confidence: 95%

Dephasing of free carriers and excitons in bulk CdTe

Sprinzl

Kunc

Ostatnický

et al. 2007

Self Cite

“…Following our recent work on the temperature dependence of the fundamental energy band-gap (E g ) in CdTe [10], we conclude that the NBEL maximum lies below the FX resonance (1.516 eV at 300 K [10]). Based on these facts, we propose a completely new interpretation of the NBEL band's origin.…”

Section: Introductionmentioning

confidence: 85%

“…In the following text this rectification of PL shape is done. Figure 7 shows the temperature evolution of the E g (T) dependence [10] and of dips and maxima of the edge PL for several samples, and also together data from [7]. Based on the detailed analysis of the absorption coefficient of thin samples [10], we demonstrate that the maximum of the RT NBEL is below both the energy gap and the FX resonance (also see Fig.…”

Section: Nature Of Room Temperature Photoluminescencementioning

confidence: 92%

“…Samples for PL measurements were polished and chemically etched by a solution of bromine in methanol. CdTe samples for transmittance measurement were mechanically polished to the thickness of 12 µm and further thinned by etching to 2-3 µm (their preparation is described in [10]). Photoluminescence and transmittance measurements were carried out using Fourier-transform infrared spectrometer Bruker IFS 66/S and flow helium cryostat Leybold Hereaus VSK 4-300.…”

Section: Methodsmentioning

confidence: 99%

“…For samples with a large crystal disorder, the PL spectrum does not show any dip at all. This characteristic PL dip, if present, can be used to determine the sample temperature (using a suitable temperature dependence of the E g [10]) or the zinc content for the ternary Cd 1-x Zn x Te alloy [13]. We will derive in this paragraph a simple theoretical model describing the photo-excited particle (electrons, holes or excitons) concentration profile near the sample surface in order to evaluate exactly the correction of the PL spectra for the variation of the absorption coefficient.…”

Section: -100 K Reabsorption Of Pl By Fx Resonancementioning

confidence: 99%

See 2 more Smart Citations

Band‐edge photoluminescence in CdTe

Horodyský¹,

Grill

Hlı́dek

2006

Self Cite

PACS 71.35. Cc, 78.40.Fy, 78.55.Et Near band-gap photoluminescence (PL) and absorption of bulk crystals of CdTe were measured over a wide range of temperatures (4 -500 K). It is demonstrated that the high-temperature (above 150 K) PL intensity correlates with a lower quality of the samples and quasiparticle localization induced by the crystal potential fluctuations. The influence of the high absorption coefficient at the free-exciton resonance energy on the PL spectra is analytically studied by solving the diffusion-recombination equation. We show that the reabsorption of the radiation by the free-exciton states creates two illusory PL maxima. No dead surface layer is needed to explain reabsorption effects. The room-temperature PL maximum matches neither the free-exciton resonance nor the band-gap energy. The high temperature PL is explained by the recombination of electrons and holes localized on potential fluctuations.

Photoelectric and photoluminescence properties of CdTe–GaTe composite

Caraman

Spalatu

Evtodiev

et al. 2016

A GaTe-CdTe composite was obtained by thermal treatment at 1020 K of GaTe single crystals in Cd vapor atmosphere. The composite photoluminescence, photoconductivity, and composition are studied in this work. The photosensitivity and photoluminescence band structure are determined for both the primary crystals and the composite. The CdTe crystallites create, in the GaTe bandgap, recombination and trapping levels, which determine the structure of the photoluminescence spectra and the spectral range of composite photosensitivity. The photoluminescence spectrum of the composite at 80 K contains characteristic bands of both composite components, GaTe and CdTe. From the analysis of thermally stimulated luminescence curves, the energies of the electron trapping levels in the composite are determined.