Photoluminescence Of Zincselenide Single Crystals Annealed In Zinc Or Selenium Atmosphere

1994 ◽  
Vol 348 ◽  
Author(s):  
Kenji Yoshino ◽  
Yasushi Matsushima ◽  
Hiroyoshi Kinoshita ◽  
Makoto Hiramatsu
Keyword(s):  
Single Crystals ◽  
Grown Crystal ◽  
Free Exciton ◽  
Bandgap Energy ◽  
Reflection Spectroscopy ◽  
Exciton Line ◽  
Annealing Effects ◽  
Sublimation Method ◽  
Pl Spectrum

ABSTRACTZincselenide single crystals grown by the sublimation method are annealed in Zn or Se atmosphere. The annealing effects are examined by means of photoluminescence (PL) and reflection spectroscopy at 4.2 K. In the PL spectrum for the as-grown crystal, bound exciton lines (I2, I1) are observed. For the Zn-annealed crystal, the free exciton line is clearly observed. For the Se-annealed crystal, peak positions of all lines shift to the higher energies and all lines become sharp, compared with the spectra for the as-grown crystal. It is concluded that Sc-vacancies affect the bandgap energy more than Zn-vacancies do.

The Effects Of Substitutional Alkaline Metals In Zinc Vacancy Of Zincselenide Single Crystals Grown By The Sublimation Method

1996 ◽  
Vol 442 ◽  
Author(s):  
Kenji Yoshino ◽  
Kouji Maeda ◽  
Atsuhiko Fukuyama ◽  
Yoshito Akashi ◽  
Kiyohisa Imada ◽  
...  
Keyword(s):  
Single Crystals ◽  
Free Exciton ◽  
Energy Shift ◽  
Acceptor Pair ◽  
Deep Acceptor ◽  
Impurity Atoms ◽  
Peak Energy ◽  
Sublimation Method ◽  
Donor Acceptor ◽  
Metal Doped

AbstractThe photoluminescence measurements of alkaline metal doped zincselenide (ZnSe) single crystals were carried out to investigate how the impurity atoms substitute the intrinsic vacancy. Sample are grown by the sublimation method and the Li and Na with the concentrations of 0.1, 0.25 and 0.5 mol% were incorporated simultaneously. In the PL spectra with lower impurity concentrations, bound exciton lines of deep acceptor and donor-acceptor pair (DAP) bands were clearly observed accompanied by a weak free exciton line. Although the bound exciton lines becomes smaller with increasing the impurity concentration, the DAP band remains strong and its peak energy shift to lower energy side with the concentration. The decrease of the bound exciton lines is drastic for Li-doped sample than Na-doped sample. This indicates that Li atoms more easily occupy the Zn vacancies than Na.

Studies on the Temperature Stability of Pure and Doped Triglycine Sulphate Crystals Using TGA/DTA

2020 ◽  
Vol 10 (3) ◽  
pp. 206-212
Author(s):  
Vijeesh Padmanabhan ◽  
Maneesha P. Madhu ◽  
Supriya M. Hariharan
Keyword(s):  
Thermal Analysis ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Temperature Stability ◽  
Bandgap Energy ◽  
Dsc Analysis ◽  
Slow Cooling ◽  
As Doping ◽  
Similar Dependence ◽  
Temperature Ranges

Aim: To study the temperature stability of TGS doped with ZnSO4, CdCl2, BaCl2, and compare it with that of pure TGS. Objectives: Synthesizing pure and doped TGS and studying their temperature dependence using TGA, DTA, and DSC analysis. Methods: Slow cooling solution growth was used to grow single crystals of pure and doped TGS. The TGA, DTA and DSC analysis was conducted for determining the temperature stability. Results: The thermal analysis of pure and doped TGS shows that the doped samples show a similar dependence on temperature as pure TGS. The temperature of decomposition of pure and doped samples (BTGS, ZTGS, CdTGS) was 226.60°C, 228.38°C, 229.13°C, and 239.13°C respectively. The melting onset of these samples was 214.51°C, 216.04°C, 217.69°C and 216.04°C respectively. Conclusion: The study shows that doping TGS with the above three described materials did not alter their temperature stability considerably. It is a good result as doping TGS, for varying its characteristics like absorbance, reflectance, bandgap energy, etc., which did not alter its temperature stability. Therefore, TGS doped with the above three dopants can be used at the same temperature ranges as of pure TGS but with much-improved efficiency.

Anthracene fluorescence at low temperatures. I. Purified single crystals

1972 ◽  
Vol 25 (7) ◽  
pp. 1411 ◽  
Author(s):  
LE Lyons ◽  
LJ Warren
Keyword(s):  
Low Temperature ◽  
Single Crystals ◽  
Fluorescence Spectrum ◽  
Low Temperatures ◽  
Free Exciton ◽  
Deformation Bands ◽  
Exciton Emission ◽  
Polarized Emission ◽  
Impurity Bands ◽  
Phonon Structure

The low-temperature fluorescence spectrum of purified vapour-grown anthracene single crystals is presented and the free-exciton emission distinguished from a number of defect or impurity bands present even in the purest crystals. In assigning the observed bands the symmetry of the active vibrations and the origin of background fluorescence and deformation bands are discussed. The phonon structure in the region of the fluorescence origin was found to be almost completely b-polarized. Emission of electronic origin (25103 cm-1) was too weak to be observed. Polarization ratios of the principal vibronio bands at 5.6 K are given.

scholarly journals Discontinuities at the melting point of bismuth

1931 ◽  
Vol 133 (821) ◽  
pp. 162-172 ◽  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Random Distribution ◽  
Grown Crystal ◽  
Perfect Crystal ◽  
Real Property ◽  
Resistance Change ◽  
X Ray ◽  
Almost All ◽  
Brittle Crystals

During the last two or three years considerable attention has been given to the growth of single crystals of bismuth and to their physical properties. The result of this work has shown that the preparation of a good single crystal is exceedingly difficult, the process being easily disturbed in many ways, and the conclusion must be drawn that it has not yet been possible to obtain anything approaching a perfect crystal. In all cases where the grown crystal has been adequately examined, it has been necessary to admit that the supposed single crystal was full of discontinuities. This was shown by Kapitza* in his work on the growth and magneto­-resistance change of single crystals of bismuth. He found it very difficult to produce a crystal rod parallel to the hexagonal axis that was flexible. Almost all the crystals grown with this orientation were apparently brittle in that a very little strain would cause a sharp fracture parallel to the principal cleavage plane. Some crystals indeed broke up into small pieces 2 or 3 mm. long when dropped from a height of a few centimetres on a table. As the separate pieces proved to be fairly flexible this brittleness is not a real property of the crystal, but appears to be due to isolated cracks or discontinuities in the crystal (the word “crack” is used with the meaning defined by Kapitza in his paper, where further arguments for their existence from X-ray and resistance measurements are given). These cracks are not characteristic only of the brittle crystals, but appear to be present in many flexible crystals as well, their flexibility being due to a random distribution of a comparatively large number of cracks small in area compared to the dimensions of the rod.

The Method for Enhancing Nitrogen Doping in 6H-SiC Single Crystals Grown by Sublimation Process: The Effect of Si Addition in SiC Powder Source

2006 ◽  
Vol 527-529 ◽  
pp. 55-58 ◽  
Author(s):  
Kwan Mo Kim ◽  
Soo Hyung Seo ◽  
Jae Woo Kim ◽  
Joon Suk Song ◽  
Myung Hwan Oh ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Single Crystals ◽  
Nitrogen Doping ◽  
Doping Concentration ◽  
Silicon Powder ◽  
Mixed Powder ◽  
Nitrogen Doped ◽  
Sublimation Method ◽  
Si Content ◽  
Si Addition

The variation of nitrogen doping concentration was systematically investigated with respect to the amount of silicon powder added to the SiC powder for growing n-type 6H-SiC single crystal by the sublimation method. To change intentionally the Si content in the SiC powder, 0wt% to 2wt% of a silicon powder was added to first-thermal treated SiC powder and the mixed powder was treated again at 1800oC for 3 hours to eliminate excess free-metallic silicon. Nitrogen doped 6H-SiC single crystals were grown by using 2nd-thermal treatment SiC powder at fixed N2/(Ar + N2) (3%). The nitrogen doping concentration of 6H-SiC crystals increased with increasing Si content in the SiC powder. In this work, we could identify that the additional silicon powder in SiC powder plays a role in the enhancement of nitrogen doping in 6H-SiC crystals grown by the sublimation method.

Doping and Annealing Effects on the Optical Bandgap of the Nickel Doped Copper Oxide Thin Films

2021 ◽  
Vol 16 (2) ◽  
pp. 243-248
Author(s):  
Fatmah S. Bahabri ◽  
Alaa Y. Mahmoud ◽  
Wafa A. Alghameeti
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Doping Concentration ◽  
Cupric Oxide ◽  
Optical Bandgap ◽  
Visible Range ◽  
Bandgap Energy ◽  
Direct Bandgap ◽  
Annealing Temperatures ◽  
Annealing Effects

In this work, we study the optical properties of the Nickel doped cupric oxide Ni-CuO thin films with Ni various doping concentrations (0, 20, 30, 50, 70, and 80%), at two different annealing temperatures; 200 and 400 °C. The absorbance and optical bandgap for the films are calculated and compared. We find that all films exhibit clear peaks in the visible range, with the increase in the absorptivity via increasing both annealing and Ni concentration. We also find that the annealing affects the shape of the absorbance peaks to be narrowed and blue shifted. Investigation on the direct bandgap energy shows that all films exhibit large direct gap; ranging from 3.87 to 4.01 eV. For non-annealed films, direct bandgap increases with increasing the Ni concentration, while for the annealed samples, the direct bandgap generally decreases by annealing, and with increasing the doping concentration. For the indirect bandgap analysis, the calculated values of the bandgap are ranging from 0.62 to 1.96 eV. We find that for non-annealed films, the indirect bandgap increases with increasing the doping concentration, while after annealing, the bandgap decreases with increasing the doping concentration for the annealing at 200 and 400 °C, with more decreasing in the gap at 400 °C.

Basal plane bending of 4H-SiC single crystals grown by sublimation method with different seed attachment methods

CrystEngComm ◽  
2018 ◽  
Vol 20 (43) ◽  
pp. 6957-6962 ◽  
Author(s):  
Xianglong Yang ◽  
Jinying Yu ◽  
Xiufang Chen ◽  
Yan Peng ◽  
Xiaobo Hu ◽  
...  
Keyword(s):  
High Resolution ◽  
Single Crystals ◽  
Basal Plane ◽  
X Ray ◽  
Sublimation Method ◽  
Plane Bending

Basal plane bending of 4H-SiC single crystals grown using the sublimation method on an open or closed backside seed was measured using high-resolution X-ray diffractometry.

scholarly journals Action of the Cavity-Wall for the Synthesis of SiC Single Crystals by Sublimation Method

1968 ◽  
Vol 76 (873) ◽  
pp. 137-143 ◽  
Author(s):  
Yoshizo INOMATA ◽  
Mamoru MITOMO ◽  
Zenzaburo INOUE ◽  
Hiroshige SUZUKI
Keyword(s):  
Single Crystals ◽  
Cavity Wall ◽  
Sublimation Method

A Vibrational Analysis of Au Implanted Al2O3 Single Crystals: Ion and Thermal Annealing Effects

1992 ◽  
Vol 279 ◽  
Author(s):  
D. O. Henderson ◽  
S. H. Morgan ◽  
R. Mu ◽  
N. Chen ◽  
R. H. Magruder ◽  
...  
Keyword(s):  
Single Crystals ◽  
Thermal Annealing ◽  
Surface Plasmon ◽  
Vibrational Analysis ◽  
Amorphous Layer ◽  
Annealing Effects ◽  
Purple Color ◽  
Au Colloids

ABSTRACTThe implantation of Au into Al2O3 leads to disruption of the crystal order producing an amorphous layer. Annealing the implanted crystals at 1373 K restores the crystallinity and also imparts a purple color to the implanted layer which is attributed to a surface plasmon resulting from the formation of Au colloids.

Sign in / Sign up

Export Citation Format

Share Document