Influence of Laser Radiation on Optical Properties and Surface Structure of CdZnTe Crystal

2011 ◽  
Vol 222 ◽  
pp. 130-133 ◽  
Author(s):  
A. Mychko ◽  
Artur Medvid' ◽  
Janis Barloti ◽  
Yu. Naseka
Keyword(s):  
Laser Radiation ◽  
Surface Relief ◽  
Crystal Morphology ◽  
Interaction Process ◽  
Main Role ◽  
Optical Window ◽  
Graded Band Gap ◽  
Band Gap Structure ◽  
Thermogradient Effect ◽  
Atom Force Microscope

The change of surface of Cd0.9Zn0.1Te crystal morphology after irradiation by pulsed Nd:YAG laser has been studied. Thermogradient effect (TGE) has the main role in the interaction process of laser radiation with semiconductors. A change of the irradiated surface relief has been observed by atom force microscope. Self-organizing nano-cones are observed on the irradiated surface of Cd0.9Zn0.1Te crystal at intensity of the laser in the range of 4.0 – 12.0 MW/cm2. A graded band gap structure with optical window was formed at the top of nano-cones.

Laser Induced Nanostructure Formation on a Surface of CdZnTe Crystal

2010 ◽  
Vol 11 ◽  
pp. 107-112 ◽  
Author(s):  
Arthur Medvid ◽  
A. Mychko ◽  
A. Pludons ◽  
Yu. Naseka
Keyword(s):  
Laser Radiation ◽  
Band Gap ◽  
Nd:Yag Laser ◽  
Quantum Confinement ◽  
Optical Window ◽  
Nanometer Size ◽  
Cdznte Crystal ◽  
Graded Band Gap ◽  
Band Gap Structure ◽  
First Time

For the first time, a new PL band at 1.8718 eV is observed after irradiation of Cd1-xZnxTe (x = 0.1) crystal by Nd:YAG laser at intensity 12.0 MW/cm2. The origin of this PL band we connect with formation of strongly enriched layer by Zn atoms at the irradiated surface of the sample due to a themogradient effect. Self-organizing structures of nanometer size are observed on the surface of a CdZnTe crystal (x = 0.1) irradiated by strongly absorbed Nd:YAG laser radiation at intensities 4.0-12.0 MW/cm2. The effect of exciton quantum confinement manifested by a shift to higher energies of the A0,X exciton line in the photoluminescent spectrum is present in structures of 10–15 nm in diameter at the top of nanohills. A graded band gap structure with optical window is formed on the top of nanohills.

scholarly journals Relativistic self-focusing of transmitted laser radiation in plasmas

2000 ◽  
Vol 18 (1) ◽  
pp. 101-107 ◽  
Author(s):  
MEENU V. ASTHANA ◽  
DINESH VARSHNEY ◽  
M.S. SODHA
Keyword(s):  
Dielectric Constant ◽  
Laser Radiation ◽  
Critical Power ◽  
Interaction Process ◽  
Gaussian Laser Beam ◽  
Laser Plasma Interaction ◽  
Paraxial Ray Approximation ◽  
Self Focusing ◽  
Beam Incident ◽  
Paraxial Ray

This paper presents an analysis of relativistic self-focusing of a Gaussian laser beam incident normally on a plane interface of a linear medium and a nonlinear, nonabsorbing plasma with an intensity dependent dielectric constant. Considering the nonlinearity to arise from the relativistic variation of mass and the Lorentz force on electrons. Following Wentzel–Kramers–Brillouin (WKB) and paraxial ray approximation the phenomenon of relativistic self-focusing of the transmitted laser radiation has been analyzed for the arbitrary magnitude of nonlinearity. Change in the intensity distribution along the wavefront of the Gaussian beam, due to refraction at the interface has also been taken into account. The variation of beamwidth parameter with distance of propagation, self trapping condition and critical power has been evaluated. Numerical estimates for typical parameters of laser plasma interaction process indicate the refraction at the interface to have a significant effect on self-focusing.

Properties of Nanostructure Formed on SiO2/Si Interface by Laser Radiation

2007 ◽  
Vol 131-133 ◽  
pp. 559-562 ◽  
Author(s):  
Arthur Medvid ◽  
Igor Dmitruk ◽  
Pavels Onufrijevs ◽  
Iryna Pundyk
Keyword(s):  
Optical Properties ◽  
Laser Radiation ◽  
Band Gap ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Confinement Effect ◽  
Visible Range ◽  
Pulsed Nd:Yag Laser ◽  
Self Organized ◽  
Graded Band Gap

The aim of this work is to study optical properties of Si nanohills formed on the SiO2/Si interface by the pulsed Nd:YAG laser radiation. Nanohills which are self-organized on the surface of Si, are characterized by strong photoluminescence in the visible range of spectra with long wing in the red part of spectra. This peculiarity is explained by Quantum confinement effect in nanohillsnanowires with graded diameter. We have found a new method for graded band gap semiconductor formation using an elementary semiconductor. Graded change of band gap arises due to Quantum confinement effect.

scholarly journals Noise minimised high resolution digital holographic microscopy applied to surface topography

2018 ◽  
Vol 42 (2) ◽  
pp. 267-272 ◽  
Author(s):  
E. Achimova ◽  
V. Abaskin ◽  
D. Claus ◽  
G. Pedrini ◽  
I. Shevkunov ◽  
...  
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Surface Relief ◽  
Digital Holographic Microscopy ◽  
Surface Microstructure ◽  
Wavefront Reconstruction ◽  
Quantitative Measurements ◽  
Holographic Microscopy ◽  
Surface Relief Gratings ◽  
Atom Force Microscope

The topography of surface relief gratings was studied by digital holographic microscopy. The applicability of the method for quantitative measurements of surface microstructure at nanoscale was demonstrated. The method for wavefront reconstruction of surface relief from a digital hologram recorded in off-axis configuration was also applied. The main feature is noise filtration due to the presence of noise in the recorded intensity distribution and the use of all orders of the hologram. Reconstruction results proved a better effectiveness of our approach for topography studying of relief grating patterned on a ChG As2S3 – Se nanomultilayers in comparison with standard Fourier Transform and Atom Force Microscope methods.

Formation Chemistry of Polycrystalline Cu(InGa)Se2 Thin-Film Absorbers Prepared by Selenization of Cu-Ga/In Stacked Precursor Layers with H2Se Gas

1996 ◽  
Vol 426 ◽  
Author(s):  
K. Kushiya ◽  
S. Kuriyagawa ◽  
T. Kase ◽  
I. Sugiyama ◽  
M. Tachiyuki ◽  
...  
Keyword(s):  
Thin Film ◽  
Band Gap ◽  
Fabrication Process ◽  
Simplified Model ◽  
Cigs Thin Film ◽  
Precursor Layer ◽  
Graded Band Gap ◽  
Band Gap Structure ◽  
Selenization Process ◽  
Gap Structure

AbstractThe purpose of this study is to improve the reliability and reproducibility of our fabrication process for polycrystalline Cu(InGa)Se2 (CIGS) thin-film absorbers and to make a better absorber with higher efficiency. The current baseline process of selenization has been evaluated through the investigation of the formation chemistry of the device-quality CIGS thin-film absorbers with a graded band-gap structure. It has been verified that the current selenization process has been performed in a good balancing point with both Cu/III ratio and thickness of the precursor layer and the total amount of Se through H2Se gas incorporated from the surface during the selenization. A simplified model to explain the formation chemistry of the selenization in this study has been proposed.

Homo- and Hetero-Structure Formation in Semiconductors by Laser Radiation: First Stage of Quantum Cones Formation

2013 ◽  
Vol 205-206 ◽  
pp. 475-479 ◽  
Author(s):  
Artur Medvids ◽  
Pavels Onufrijevs ◽  
Edvins Dauksta ◽  
Nikolai A. Sobolev
Keyword(s):  
Laser Radiation ◽  
Solid Solutions ◽  
Point Defects ◽  
Radiation Absorption ◽  
Gradient Field ◽  
Hetero Structure ◽  
Impurity Atoms ◽  
Cone Formation ◽  
New Phase ◽  
Thermogradient Effect

A possibility of formingquantum cones (QC) by Nd:YAG laser radiation on the surface of semiconductorssuch as Si and Ge crystals, and SiGe and CdZnTe solid solutions has been shown.A two-stage mechanism of quantum cone formation has been proposed. The first stage is generation and redistribution of point defects (impurity atoms and intrinsic point defects – vacancies and self-interstitials) in a temperature gradient field, the so-called thermogradient effect. As a result a new phase is formed on the irradiated surface, for example a Ge phase forms on the surface of a SiGe solid solution. The second stage is characterized by mechanical plastic deformation of the strained top layer leading to the formation of quantum cones, due to selective laser radiation absorption of the top layer. The first stage is more difficult for understanding of the physical processes which takeplace during of growth of QC, especially in pure intrinsic elementary semiconductors (Ge, Si) and compounds (CdTe, GaAs). Therefore, this research is focused on the investigation of the first stage of QC formation by laser irradiation. As a result of the investigation, a new mechanism for p-n junction formation in the elementary semiconductors and heterojunction in solid solutions by laser radiation as a first stage of QC formation is proposed.

EXCITATION OF SURFACE CAPILLARY WAVES BY SPATIALLY PERIODICAL LASER RADIATION

2004 ◽  
Vol 13 (01) ◽  
pp. 1-6 ◽  
Author(s):  
R. S. HAKOBYAN ◽  
B. YA. ZELDOVICH
Keyword(s):  
Laser Radiation ◽  
Liquid Crystals ◽  
Light Intensity ◽  
Surface Relief ◽  
Capillary Waves ◽  
Hydrodynamic Waves ◽  
Polymer Dispersed Liquid Crystals ◽  
Polymer Dispersed ◽  
Theoretical Results ◽  
Zero Frequency

In this paper we report theoretical results on thermocapillary hydrodynamic waves induced by travelling spatially periodical distribution of light intensity. The phase of the local elevation in capillary waves is close to the phase of interference pattern when the frequency is far from zero and from eigenfrequency of free capillary waves. This phase difference is exactly π/2 for zero frequency. Predicted thermocapillary mechanism of induced surface waves and boundary disturbances can have an important role for surface relief grating in the polymer-dispersed liquid crystals.

Increase of Solar Cell Efficiency in Graded Band Gap Structure

2015 ◽  
Vol 1117 ◽  
pp. 114-117
Author(s):  
J. Kaupužs ◽  
Arturs Medvid'
Keyword(s):  
Solar Cell ◽  
Band Gap ◽  
High Surface ◽  
Surface Recombination ◽  
Surface Recombination Velocity ◽  
Solar Cell Efficiency ◽  
Cell Efficiency ◽  
Recombination Velocity ◽  
Graded Band Gap ◽  
Band Gap Structure

The photo current-voltage characteristic of a solar cell with graded band gap is calculated numerically based on the drift-diffusion equation and Poisson equation. The calculated efficiency of the CdTe solar cell with p-n junction located in 1μm depth increases remarkably when the band gap of the front n-type layer is graded. The effect is strong for high surface recombination velocity and is remarkable even at: the calculated efficiency increases from 19.6% to 24.3%.

Suppression of Pores Formation on a Surface of p-Si by Laser Radiation

2009 ◽  
Vol 156-158 ◽  
pp. 337-341 ◽  
Author(s):  
Arthur Medvid ◽  
Pavels Onufrijevs ◽  
L. Fedorenko ◽  
N. Yusupov ◽  
Edvins Dauksta
Keyword(s):  
Laser Radiation ◽  
Electrochemical Etching ◽  
Morphological Changes ◽  
Optical Microscope ◽  
Optical Recording ◽  
Atomic Force ◽  
Porous Part ◽  
P Type ◽  
And Storage ◽  
Thermogradient Effect

The influence of strongly absorbing N¬2 laser radiation on pores formation on a surface of Si single crystal has been investigated using optical microscope, atomic force microscope and photoluminescence. After irradiation by the laser and subsequent electrochemical etching in HF acid solution morphological changes of the irradiated parts of a surface of Si were not observed. At the same time, pores formation on the non-irradiated parts of Si surface took place. The porous part of the Si surface is characterized by strong photoluminescence in red part of spectra with maximum at 1.88 eV and intensity of photoluminescence increases with current density. Suppression of the pores formation by the laser radiation is explained with inversion of Si type conductivity from p-type to n-type. This fact is explained by Thermogradient effect – generation and redistribution of the intrinsic defects in gradient of temperature. It was shown that the depth of n-Si layer on p-Si substrate depends on intensity of laser radiation and it increases with intensity of laser radiation. The results of the investigation can be used for optical recording and storage of information on surface of semiconductors.

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