共查询到20条相似文献,搜索用时 640 毫秒
1.
Single crystals of zirconium diselenide (ZrSe2) were grown by chemical vapour transport method using iodine as the transporting agent. The crystals were found to exhibit
metallic behaviour in the temperature range 77–300 K and semiconducting nature in 300–443 K range. The measurements of thermoelectric
power and conductivity enabled the determination of both carrier mobility and carrier concentration. The variation of carrier
mobility and carrier concentration with temperature indicates the presence of deep trapping centres and their reduction with
temperature in these crystals. 相似文献
2.
Single crystals of ternary mixed compounds of group IV-VI in the form of a series, SnSxSe1-x (wherex = 0, 0.25, 0.50, 0.75 and 1), have been grown using direct vapour transport technique. The grown crystals were characterized
by the X-ray diffraction analysis for their structural parameter determination. All the grown crystals were found to be orthorhombic.
The microstructure analysis of the grown crystals reveals their layered type growth mechanism. From the Hall effect measurements
Hall mobility, Hall coefficient and carrier concentration were calculated with all crystals showingp-type nature. The d.c. electrical resistivity measurements perpendicular toc-axis (i.e. along the basal plane) in the temperature range 303–453 K were carried out for grown crystals using four-probe
method. The d.c. electrical resistivity measurements parallel to c-axis (i.e. perpendicular to basal plane) in the temperature
range 303–453 K were carried out for the same crystals. The electrical resistivity measurements showed an anisotropic behaviour
of electrical resistivity for the grown crystals. The anisotropic behaviour and the effect of change in stoichiometric proportion
of S and Se content on the electrical properties of single crystals of the series, SnSxSe1-x (wherex = 0, 0.25, 0.50, 0.75 and 1), is presented systematically. 相似文献
3.
A series of zirconium sulphoselenide (ZrS
x
Se3−x
, where x = 0, 0·5, 1, 1·5, 2, 2·5, 3) single crystals have been grown by chemical vapour transport technique using iodine as a transporting
agent. The optimum condition for the growth of these crystals is given. The stoichiometry of the grown crystals were confirmed
on the basis of energy dispersive analysis by X-ray (EDAX) and the structural characterization was accomplished by X-ray diffraction
(XRD) studies. The crystals are found to possess monoclinic structure. The lattice parameters, volume, particle size and X-ray
density have been carried out for these crystals. The effect of sulphur proportion on the lattice parameter, unit cell volume
and X-ray density in the series of ZrS
x
Se3−x
single crystals have been studied and found to decrease in all these parameters with rise in sulphur proportion. The grown
crystals were examined under optical zoom microscope for their surface topography study. Hall effect measurements were carried
out on grown crystals at room temperature. The negative value of Hall coefficient implies that these crystals are n-type in nature. The conductivity is found to decrease with increase of sulphur content in the ZrS
x
Se3−x
series. The electrical resistivity parallel to c-axis as well as perpendicular to c-axis have been carried out in the temperature range 303–423 K. The results obtained are discussed in detail. 相似文献
4.
Sn0.2Bi1.8Te3 thin films were grown using the thermal evaporation technique on a (001) face of NaCl crystal as a substrate at room temperature.
The optical absorption was measured in the wave number range 500–4000 cm−1. From the optical absorption data the band gap was evaluated and studied as a function of film thickness and deposition temperature.
The data indicate absorption through direct interband transition with a band gap of around 0.216 eV. The detailed results
are reported here. 相似文献
5.
A. Finley D. Schleich J. Ackerman S. Soled A. Wold 《Materials Research Bulletin》1974,9(12):1655-1659
Large, well-formed plates of Pt0.97 S2 were grown by chemical vapor transport. A combination of phosphorus and chlorine was used as the transport agent. The best crystals were grown when the charge zone was maintained at 800°C and the growth zone at 740°C. The crystals were found to be diamagnetic with a susceptibility of ?31(2) × 10?6 emu/mole at 77°K and showed semiconducting behavior with a band gap of 0.20(2)eV. From Hall voltage measurements, the sign of the carriers was ascertained to be positive. Pt0.97S2 particles less than 63μ underwent thermal decomposition in air at 270(10)°C. 相似文献
6.
H.T. Shaban 《Materials Chemistry and Physics》2010,119(1-2):131-134
TlGaSe2 single crystals were grown by modified Bridgman method. The crystals were identified structurally by X-ray diffraction. Measurements of electrical conductivity and Hall effect were performed in the range (200–492 K) and (163–602 K) for thermoelectric power (TEP) measurements. Anisotropic nature of the layered TlGaSe2 crystal was investigated. Hall effect and thermoelectric power measurements revealed the extrinsic p-type conduction in the low temperature range of the study. The analysis of the temperature-dependent electrical conductivity and carrier concentration reveal that the acceptor level is located at 0.2 eV above the valence band of TlGaSe2. From the obtained experimental data, the main characteristic parameters of the crystals have been estimated. Energy gap and acceptor concentration were 2.23 eV and 9.6 × 1013 cm?3 respectively. 相似文献
7.
N. M. Shah J. R. Ray V. A. Kheraj M. S. Desai C. J. Panchal Bharti Rehani 《Journal of Materials Science》2009,44(1):316-322
Copper indium diselenide (CuInSe2) compound was synthesized by reacting its elemental components, i.e., copper, indium, and selenium, in stoichiometric proportions
(i.e., 1:1:2 with 5% excess selenium) in an evacuated quartz ampoule. Structural and compositional characterization of synthesized
pulverized material confirms the polycrystalline nature of tetragonal phase and stoichiometry. CuInSe2 thin films were deposited on soda lime glass substrates kept at different temperatures (300–573 K) using flash evaporation
technique. The effect of substrate temperature on structural, morphological, optical, and electrical properties of CuInSe2 thin films were investigated using X-ray diffraction analysis (XRD), atomic force microscopy (AFM), optical measurements
(transmission and reflection), and Hall effect characterization techniques. XRD analysis revealed that CuInSe2 thin films deposited above 473 K exhibit (112) preferred orientation of grains. Transmission and reflectance measurements
analysis suggests that CuInSe2 thin films deposited at different substrate temperatures have high absorption coefficient (~104 cm−1) and optical energy band gap in the range 0.93–1.02 eV. Results of electrical characterization showed that CuInSe2 thin films deposited at different substrate temperatures have p-type conductivity and hole mobility value in the range 19–136 cm2/Vs. Variation of energy band gap and resistivity of CuInSe2 thin films deposited at 523 K with thickness was also studied. The temperature dependence of electrical conductivity measurements
showed that CuInSe2 film deposited at 523 K has an activation energy of ~30 meV. 相似文献
8.
A. Sivasankar Reddy P. Sreedhara Reddy S. Uthanna G. Mohan Rao 《Journal of Materials Science: Materials in Electronics》2006,17(8):615-620
Thin films of copper aluminum oxide (CuAlO2) were prepared on glass substrates by dc magnetron sputtering at a substrate temperature of 523 K under various oxygen partial
pressures in the range 1 × 10−4–3 × 10−3 mbar. The dependence of cathode potential on the oxygen partial pressure was explained in terms of oxidation of the sputtering
target. The influence of oxygen partial pressure on the structural, electrical and optical properties was systematically studied.
p-Type CuAlO2 films with polycrystalline nature, electrical resistivity of 3.1 Ω cm, Hall mobility of 13.1 cm2 V−1 s−1 and optical band gap of 3.54 eV were obtained at an oxygen partial pressure of 6 × 10−4 mbar. 相似文献
9.
M.P. Deshpande J.B. Patel Nilesh N. Pandya M.N. Parmar G.K. Solanki 《Materials Chemistry and Physics》2009,117(2-3):350-354
Single crystals of rhenium doped tungsten diselenide i.e. RexW1−xSe2 (x = 0, 0.0005, 0.001, 0.05, 0.1) are grown by vapour phase technique. The stoichiometry of grown single crystals is confirmed by energy dispersive analysis of X-rays. X-ray powder diffractograms obtained of these compounds were used for lattice parameter determination based on hexagonal system similar to that of host WSe2.The crystallite size for each sample for different reflection is calculated using Scherrer's formula. Surface morphology as observed under optical microscope reflects that screw dislocation mechanism is responsible for growth of crystals. Electrical properties viz. Hall effect at room temperature, resistivity measurements at low temperature, and high pressure resistivity measurements indicates the semiconducting behaviour of RexW1−xSe2 (x = 0, 0.0005, 0.001, 0.05, 0.1) single crystals. Thermoelectric power measurements shows p-type nature of host WSe2 whereas n-type nature of rhenium doped WSe2 which matches with the results of Hall effect. 相似文献
10.
Large single crystals of a few important members (x=0, 1, 2) of the series ZrS
x
Se2−x
compounds have been obtained by chemical vapour (iodine) transport method. The crystals have been characterized for several
properties. Their semiconducting nature is inferred from resistivity vs temperature measurements, their optical absorption
data reveal indirect gap transitions, their thermoscans indicate their stability over a limited temperature range, and they
essentially grow by the mechanism of two dimensional layer propagation. 相似文献
11.
The sample thickness effect on the optical properties of TlInS2 layered crystals has been investigated at room temperature. The absorption coefficient of the samples calculated from the
experimental transmittance and reflectance in the photon energy range of 1.10–3.10 eV has two absorption regions. The first
is a long-wavelength region of 1.16–1.28 eV. The second region lies above 2.21 eV with a thickness-dependent indirect band
gap. The energy gap decreases from 2.333 to 2.255 eV as the sample thickness increases from 27 to 66 μm. The differential
spectra of absorption coefficient demonstrates the existence of a thickness-dependent impurity level being lowered from 2.360
to 2.307 eV as sample thickness increases from 27 to 66 μm. 相似文献
12.
Metin Bedir Mustafa Öztaş Hüsniye Kara 《Journal of Materials Science: Materials in Electronics》2013,24(2):499-506
Boron doped CdS films have been deposited by spray pyrolysis method onto glass substrate temperature in the range of 350–450 °C. And the effect of substrate temperature (T s) on the structural, electrical and optical properties of the films were studied. The structural properties of boron doped CdS films have been investigated by (XRD) X-ray diffraction techniques. The X-ray diffraction spectra showed that boron doped CdS films are polycrystalline and have a hexagonal (wurtzite) structure. By using SEM analysis, the surface morphology of the films was observed as an effect of the variation of substrate temperature. The substrate temperature is directly related with the shift detected in the band gap values derived from optical of parameters and the direct band gap values were found to be in the region of 2.08–2.44 eV. The electrical studies showed that the film deposited at the substrate temperature 400 °C had high carrier concentration and Hall mobility and minimum resistivity. This resistivity value decreased with increase in temperature up to 400 °C indicating the semiconducting nature of B- doped CdS films. The lattice parameter, grain size, microstrain and dislocation densities were calculated and correlated with the substrate temperature (T s ). 相似文献
13.
Synthesis and characterizations of CdS nanorods by SILAR method: effect of film thickness 总被引:1,自引:0,他引:1
D. S. Dhawale D. P. Dubal M. R. Phadatare J. S. Patil C. D. Lokhande 《Journal of Materials Science》2011,46(14):5009-5015
In this investigation, we have successfully synthesized CdS nanorods by simple and inexpensive successive ionic layer adsorption
and reaction (SILAR) method. The effect of film thickness on the physico-chemical properties such as structural, morphological,
wettability, optical, and electrical properties of CdS nanorods has been investigated. The XRD pattern revealed that CdS films
are polycrystalline with hexagonal crystal structure. SEM and TEM images showed that CdS film surface are composed of spherical
grains along with some spongy cluster and an increase in film thickness up to 1.23 μm causes the formation of matured nanorods
having diameter 150–200 nm. The increases in water contact angle form 105° to 130° have been observed as film thickness increases
from 0.13 to 1.23 μm indicating hydrophobic nature. The optical band gap was found to be increased from 2.02 to 2.2 eV with
increase in film thickness. The films showed the semiconducting behavior with room temperature electrical resistivity in the
range of 104–106 Ω cm and have n-type electrical conductivity. 相似文献
14.
M. A. Abdullaev A. K. Akhmedov D. Kh. Magomedova P. P. Khokhlachev 《Inorganic Materials》2012,48(10):987-990
n-Type AgInSe2 films 0.5 to 0.9 μm thick were grown by dc magnetron sputtering. As targets, we used AgInSe2 crystals grown by a modified Bridgman process using high-purity precursors. The crystal structure, morphology, electrical conductivity, and Hall coefficient of the films were studied at various temperatures. We determined the optimal growth and annealing temperatures of the films (500 and 250°C, respectively). Using structures based on the films, we obtained the spectral dependences of their photoresponse, established the nature of interband transitions in the films, and evaluated their band gap. The ability to vary electrical and optical properties with no changes in stoichiometry is of interest for concentrated solar power applications. 相似文献
15.
C. H. Liang K. K. Tiong Y. S. Huang D. Dumcenco C. H. Ho 《Journal of Materials Science: Materials in Electronics》2009,20(Z1):476-479
Au-doped ReS2 layer crystals were grown by chemical vapour method with iodine as the transport agent. Room temperature Hall effect measurement
showed p-type semiconducting character for the doped sample. The electrical conductivities parallel and perpendicular to the
crystal b-axis were investigated. The near band-edge temperature-dependent in-plane anisotropic optical properties were studied by
the polarization-dependent photoconductivity measurements, with the incident light beam parallel and perpendicular to the
crystal b-axis, in the temperature range from 20 to 300 K. The influence of Au in the measured conductivity anisotropy and photoconductivity
spectra of doped ReS2 were analysed and discussed. 相似文献
16.
K. Venkata Subba Reddy A. Sivasankar Reddy P. Sreedhara Reddy S. Uthanna 《Journal of Materials Science: Materials in Electronics》2007,18(10):1003-1008
Copper nitride (Cu3N) films were deposited on glass substrates by sputtering of copper target under various substrate temperatures in the range
303–523 K using dc reactive magnetron sputtering. The substrate temperature highly influenced the structural, mechanical,
electrical and optical properties of the deposited films. The X-ray diffraction measurements showed that the films were of
polycrystalline nature and exhibit preferred orientation of (111) phase of Cu3N. The microhardness of the films increased from 2.7 to 4.4 GPa with the increase of substrate temperature from 303 to 473 K
thereafter decreased to 4.1 GPa at higher temperature of 523 K. The electrical resistivity of the films decreased from 8.7 × 10−1 to 1.1 × 10−3 Ωcm and the optical band gap decreased from 1.89 to 1.54 eV with the increase of substrate temperature from 303 to 523 K
respectively. 相似文献
17.
M. Öztaş M. Bedir R. Kayalı F. Aksoy 《Journal of Materials Science: Materials in Electronics》2006,17(10):841-845
InP thin films were prepared by spray pyrolysis technique using aqueous solutions of InCl3 and Na2HPO4, which were atomized with compressed air as carrier gas. The InP thin films were obtained on glass substrates. Thin layers
of InP have been grown at various substrate temperatures in the range of 450–525°C. The structural properties have been determined
by using X-ray diffraction (XRD). The changes observed in the structural phases during the film formation in dependence of
growth temperatures are reported and discussed. Optical properties, such as transmission and the band gap have been analyzed.
An analysis of the deduced spectral absorption of the deposited films revealed an optical direct band gap energy of 1.34–1.52 eV
for InP thin films. The InP films produced at a substrate temperature 500°C showed a low electrical resistivity of 8.12 × 103 Ω cm, a carrier concentration of 11.2 × 1021 cm−3, and a carrier mobility of 51.55 cm2/Vs at room temperature. 相似文献
18.
Single crystals of the semiorganic material, dichlorobis(l-proline)zinc(II) (DCBPZ), were grown from aqueous solution. The grown crystals were tested by single crystal X-ray diffraction, energy-dispersive spectrometry, FT-IR, UV–vis and TG–DTA. The structural prefection of the grown crystals has been analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. The dielectric and mechanical behavior of the specimen was also studied. The SHG efficiency of DCBPZ is three times greater than that of KDP. Measuring transmittance of DCBPZ permitted the calculation of the refractive index n, the extinction coefficient K and both the real ?r and imaginary ?i components of the dielectric constant as functions of photon energy. The optical band gap of DCBPZ is 4.8 eV. 相似文献
19.
B Ya Kotyuzhanskii 《Bulletin of Materials Science》1991,14(3):753-758
The effect of oxygen content in the single crystals of high-temperature superconductor YBa2Cu3O7−x
on the electrical resistivity, the Hall effect in the plane perpendicular to thec axis and the energy gap Δ, measured with tunnelling electron microscope, has been studied. The distribution of the gap along
the surface of the crystal was also studied. The results of the study on the relationship between the magnitude of the energy
gap Δ and the superconducting transition temperatureT
c
of single crystals with various oxygen contents are approximated by the linear dependence 2Δav=4·4kT
c
. 相似文献
20.
We have grown Mg2Si bulk crystals by the vertical Bridgman method using a high-purity Mg (6N-up) source. The grown crystals were single-phase Mg2Si and had well-developed grains (1-5 mm3). Laue observations and SEM-EDX observations confirmed that crystalline quality in the grains was single crystal with stoichiometric composition. Electron concentration of the single crystalline specimens grown from 6N-up-Mg was 4.0 × 1015 cm− 3 at room temperature (RT). This value is more than one order of magnitude lower than that of specimens grown from 4N-Mg [(5-7) × 1016 cm− 3]. The Hall mobility of 14,500 cm2/Vs was observed at 45 K in the crystals grown from 6N-up-Mg. We also found that Al impurity plays an important role in the crystals grown from a low-purity Mg source. From the optical absorption measurement, we estimated that the indirect energy gap was about 0.66 eV at 300 K and about 0.74 eV at 4 K. 相似文献