scholarly journals The Undoped Polycrystalline Diamond Film—Electrical Transport Properties

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6113
Author(s):  
Szymon Łoś ◽  
Kazimierz Fabisiak ◽  
Kazimierz Paprocki ◽  
Mirosław Szybowicz ◽  
Anna Dychalska

The polycrystalline diamonds were synthesized on n-type single crystalline Si wafer by Hot Filament CVD method. The structural properties of the obtained diamond films were checked by X-ray diffraction and Raman spectroscopy. The conductivity of n-Si/p-diamond, sandwiched between two electrodes, was measured in the temperature range of 90–300 K in a closed cycle cryostat under vacuum. In the temperature range of (200–300 K), the experimental data of the conductivity were used to obtain the activation energies Ea which comes out to be in the range of 60–228 meV. In the low temperature region i.e., below 200 K, the conductivity increases very slowly with temperature, which indicates that the conduction occurs via Mott variable range hopping in the localized states near Fermi level. The densities of localized states in diamond films were calculated using Mott’s model and were found to be in the range of 9×1013 to 5×1014eV−1cm−3 depending on the diamond’s surface hydrogenation level. The Mott’s model allowed estimating primal parameters like average hopping range and hopping energy. It has been shown that the surface hydrogenation may play a crucial role in tuning transport properties.

1996 ◽  
Vol 8 (10) ◽  
pp. 2505-2509 ◽  
Author(s):  
V. Zima ◽  
M. Vlček ◽  
L. Beneš ◽  
M. Casciola ◽  
L. Massinelli ◽  
...  

2013 ◽  
Vol 743-744 ◽  
pp. 59-64
Author(s):  
Liang Wei Fu ◽  
Jun You Yang ◽  
Ye Xiao ◽  
Jiang Ying Peng ◽  
Ming Yang Zhang

AgSbTe2compounds have been synthesized via melting and subsequent cooling processes. The effect of cooling process, from air-cooling, water quenching to liquid nitrogen-quenching, on the microstructure and the electrical transport properties of AgSbTe2has been investigated by means of powder X-ray diffraction, electron microscope, electrical resistivity, and Hall coefficient measurements. It has been found that the cooling process has apparent influence on the microstructure and corresponding electrical properties. The phase components and morphology changed as the cooling process altered. The electrical resistivity and the Seebeck coefficient of the as-prepared samples increased from air-cooled to liquid nitrogen-quenched sample.


2013 ◽  
Vol 652-654 ◽  
pp. 576-580 ◽  
Author(s):  
Mya Theingi ◽  
Ji Ma ◽  
Hui Zhang ◽  
Xiang Gao ◽  
Jian Hong Yi ◽  
...  

Manganite perovskite La1-xCaxMnO3(x=0.33, 0.5 and 0.9) have been prepared by chemical co-precipitation method. Ammonium carbonate was used to coprecipitate lanthanum, calcium and manganese ions as carbonates under basic condition. This precursor on calcining at 900°C yields La-Ca-Mn-O perovskite phase. Follow by sintering at 1200°C after the powders were pressed into pellets gave La1-xCaxMnO3(LCMO) polycrystalline ceramics. The crystal phases of the resulting powders and ceramics were examined by X-ray diffraction (XRD) technique. The morphology of the powders was observed by scanning electron microscopy (SEM) and electrical transport properties of ceramics were measured by conventional four-point probe technique.


2003 ◽  
Vol 793 ◽  
Author(s):  
Yasuhiro Ono ◽  
Shingo Inayama ◽  
Hideaki Adachi ◽  
Satoshi Yotsuhashi ◽  
Yuzuru Miyazaki ◽  
...  

ABSTRACTElectrical transport properties of NbCoSn1−xSbx (x =0, 0.01, 0.02 and 0.05), a half-Heusler compound and its alloys, have been studied in the temperature range from 80 K to 850 K. As-prepared samples exhibit metallic conduction and similar Seebeck coefficients near 300 K (S = –100 μVK−1). Except for NbCoSn0.95Sn0.05, both electrical resistivity, ρ, and the absolute value of S appreciably increase during the annealing for 6 days at 1123 K. Unusual increase in ρ of the annealed NbCoSn sample is found at about 200 K. ρ-T curves of the other annealed samples remain metallic over the measured temperature range and the ρ value noticeably decreases with increasing Sb content, x. Among the annealed samples, the high power factor, 25×10−4 Wm−1K−2 at 850 K, is obtained for NbCoSn0.95Sb0.05. The band structure of NbCoSn is calculated based on the determined crystal structure, indicating that NbCoSn is an indirect transition-type semiconductor with a band gap of approximately 1 eV. This is not consistent with the metallic behavior of ρ observed for the annealed NbCoSn sample above 400 K. Partial disordering of Nb and Co atoms is a conceivable answer.


2013 ◽  
Vol 800 ◽  
pp. 398-401 ◽  
Author(s):  
Qiang Wang ◽  
Ping Duan ◽  
Ji You Wang ◽  
Lei Chang ◽  
Jin Liang Zhao ◽  
...  

The polycrystalline La0.62Sb0.38MnO3 sample has been prepared by the solid-state reaction method. Structural, magnetic and electrical transport properties have been researched. X-ray diffraction analysis confirms the hexagonal crystal symmetry. Magnetization measurements indicate La0.62Sb0.38MnO3 experienced from paramagnetic to ferromagnetic state transition with decreasing temperature at about 225 K. Resistivity dependences on temperature exhibit metal-insulator transition (MIT), and the maximum magnetoresistance (MR) ratio is about 33 % at temperature of 189 K and magnetic field of 2 T.


2012 ◽  
Vol 12 (3) ◽  
pp. 765-772 ◽  
Author(s):  
B. Prasanna Lakshmi ◽  
M. Siva Pratap Reddy ◽  
A. Ashok Kumar ◽  
V. Rajagopal Reddy

2012 ◽  
Vol 510-511 ◽  
pp. 487-492
Author(s):  
M. Akram ◽  
M. Anis-ur-Rehman ◽  
S. Nasir ◽  
G. Asghar

Magnetic nanocomposites are offering a variety of novel features and tune able properties, mainly depending on particle size, cation distribution, morphology and porosity of the prepared materials. The aim of this research work is to understand the effects of Mn doping on the microstructures and hence consequences on the electrical transport properties with shift of cation distribution in CoFe2O4. Co1-xMnxFe2O4nanocrystallite particles with stoichiometric proportion (x) varying from 0.0 to 1.0 were prepared by co-precipitation method. X-ray diffraction patterns confirmed the FCC spinel structure of synthesized particles. The crystal structure is found to be inverse cubic spinel with a space group Fd3m and the lattice constants ranges from 8.36 Å to 8.46 Å The crystallite sizes were calculated from the most intense peak (311) using the Debye-Scherrer formula for all the samples those were synthesized at reaction temperature of 70°C. Then samples were sintered at 600°C for 3 hours, characterized by X-ray diffraction at room temperature and DC electrical resistivity measurements were done as a function of temperature by two-probe method from 370 K to 690 K. The measurements showed that DC electrical resistivity decreased with increase in temperature ensuring the semiconductor nature of the material in this temperature range. DC electrical resistivity results were discussed in terms of polaron hopping model under the effects of cation distribution. AC electrical properties were also analyzed. All the observed properties were correlated with observed microstructures.


1993 ◽  
Vol 07 (20) ◽  
pp. 1295-1299 ◽  
Author(s):  
P. VENUGOPAL REDDY ◽  
S. SHEKHAR ◽  
Y. PURUSHOTHAM

Electrical resistivity and thermoelectric power of glassy ribbons having compositions Fe 81 B 13.5 Si 3.5 C 2, Fe 67 Co 18 B 14 Si 1, Fe 39 Ni 39 Mo 4 Si 6 B 12, and Co 53 Ni 25 Fe 5 Si 11 B 6 have been studied over a temperature range of 300–750 K. The electrical transport properties of these materials are found to increase with increasing temperature, and their temperature variation has been explained on the basis of Ziman's theory.


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