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Femtosecond Pump Probe Reflectivity Spectra in CdTe and GaAs Crystals at Room Temperature

Ultrafast pump probe reflectivity (PPR) signal near band edge is modeled by taking into account band filling (BF) and band gap renormalization (BGR) effects with the carrier density of ~10(17)/cm(3) in GaAs crystal at room temperature. The calculated results indicate that the transient reflectivity...

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Autores principales: Sun, Hao, Ma, Hong, Leng, Jiancai
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6981574/
https://www.ncbi.nlm.nih.gov/pubmed/31935849
http://dx.doi.org/10.3390/ma13010242
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author Sun, Hao
Ma, Hong
Leng, Jiancai
author_facet Sun, Hao
Ma, Hong
Leng, Jiancai
author_sort Sun, Hao
collection PubMed
description Ultrafast pump probe reflectivity (PPR) signal near band edge is modeled by taking into account band filling (BF) and band gap renormalization (BGR) effects with the carrier density of ~10(17)/cm(3) in GaAs crystal at room temperature. The calculated results indicate that the transient reflectivity ΔR/R is determined by BF and BGR effects. The most interesting feature is that ΔR/R signal experiences a sign change from photo-bleaching (PB) to photo-absorption (PA) due to the competition between BF and BGR effects. We experimentally measured ΔR as a function of photon energy across band edge with carrier density of ~10(17)/cm(3) in GaAs and CdTe crystals, which has a similar trend as that calculated according to our model. In addition, the reflectivity is very sensitive to electron spin orientation, which is well confirmed by the corresponding experiments with 100 fs pump probe reflectivity spectroscopy in bulk CdTe. Our research in this work provides a method to study optoelectronic properties of conventional semiconductors at moderate carrier density excited by ultrafast laser pulse. Importantly, this model can be used for other novel semiconductor materials beyond GaAs and will provide new insights into the underlying spin dependent photophysics properties for new materials.
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spelling pubmed-69815742020-02-03 Femtosecond Pump Probe Reflectivity Spectra in CdTe and GaAs Crystals at Room Temperature Sun, Hao Ma, Hong Leng, Jiancai Materials (Basel) Article Ultrafast pump probe reflectivity (PPR) signal near band edge is modeled by taking into account band filling (BF) and band gap renormalization (BGR) effects with the carrier density of ~10(17)/cm(3) in GaAs crystal at room temperature. The calculated results indicate that the transient reflectivity ΔR/R is determined by BF and BGR effects. The most interesting feature is that ΔR/R signal experiences a sign change from photo-bleaching (PB) to photo-absorption (PA) due to the competition between BF and BGR effects. We experimentally measured ΔR as a function of photon energy across band edge with carrier density of ~10(17)/cm(3) in GaAs and CdTe crystals, which has a similar trend as that calculated according to our model. In addition, the reflectivity is very sensitive to electron spin orientation, which is well confirmed by the corresponding experiments with 100 fs pump probe reflectivity spectroscopy in bulk CdTe. Our research in this work provides a method to study optoelectronic properties of conventional semiconductors at moderate carrier density excited by ultrafast laser pulse. Importantly, this model can be used for other novel semiconductor materials beyond GaAs and will provide new insights into the underlying spin dependent photophysics properties for new materials. MDPI 2020-01-06 /pmc/articles/PMC6981574/ /pubmed/31935849 http://dx.doi.org/10.3390/ma13010242 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Sun, Hao
Ma, Hong
Leng, Jiancai
Femtosecond Pump Probe Reflectivity Spectra in CdTe and GaAs Crystals at Room Temperature
title Femtosecond Pump Probe Reflectivity Spectra in CdTe and GaAs Crystals at Room Temperature
title_full Femtosecond Pump Probe Reflectivity Spectra in CdTe and GaAs Crystals at Room Temperature
title_fullStr Femtosecond Pump Probe Reflectivity Spectra in CdTe and GaAs Crystals at Room Temperature
title_full_unstemmed Femtosecond Pump Probe Reflectivity Spectra in CdTe and GaAs Crystals at Room Temperature
title_short Femtosecond Pump Probe Reflectivity Spectra in CdTe and GaAs Crystals at Room Temperature
title_sort femtosecond pump probe reflectivity spectra in cdte and gaas crystals at room temperature
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6981574/
https://www.ncbi.nlm.nih.gov/pubmed/31935849
http://dx.doi.org/10.3390/ma13010242
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