scholarly journals Optical and Transport Properties of p-Type GaAs

2012 ◽  
Vol 36 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Mehnaz Sharmin ◽  
Shamima Choudhury ◽  
Nasrin Akhtar ◽  
Tahmina Begum
Keyword(s):  
Light Intensity ◽  
Carrier Concentration ◽  
Hall Coefficient ◽  
Hall Mobility ◽  
Room Temperature ◽  
Diffraction Method ◽  
Lattice Parameter ◽  
Band Gap Energy ◽  
Hall Effect Measurements ◽  
P Type

Electrical properties such as electrical resistivity, Hall coefficient, Hall mobility, carrier concentration of p-type GaAs samples were studied at room temperature (300 K). Resistivity was  found to be of the order of 5.6 × 10-3?-cm. The Hall coefficient (RH) was calculated to be 7.69 × 10-1cm3/C and Hall mobility (?H) was found to be 131cm2/V-s at room temperature from Hall effect   measurements. Carrier concentration was estimated to be 8.12 × 1018/cm3 and the Fermi level was calculated directly from carrier density data which was 0.33 eV. Photoconductivity measurements  were carried on by varying sample current, light intensity and temperature at constant chopping     frequency 45.60 Hz in all the cases mentioned above. It was observed that within the range of sample current 0.1 - 0.25mA photoconductivity remains almost constant at room temperature 300K and it was found to be varying non-linearly with light intensity within the range 37 - 12780 lux. Photoconductivity was observed to be increasing linearly with temperature between 308 and 428 K. Absorption coefficient (?) of the samples has been studied with variation of wavelength (300 -  2500 nm). The value of optical band gap energy was calculated between 1.34 and 1.41eV for the material from the graph of (?h?)2 plotted against photon energy. The value of lattice parameter (a) was found to be 5.651 by implying X-ray diffraction method (XRD).DOI: http://dx.doi.org/10.3329/jbas.v36i1.10926Journal of Bangladesh Academy of Sciences, Vol. 36, No. 1, 97-107, 2012 

P-Type Transparent Conductivity of Cu1-xAlS2 (x = 0 ~ 0.08)

2008 ◽  
Vol 368-372 ◽  
pp. 666-668 ◽  
Author(s):  
Min Ling Liu ◽  
Fu Qiang Huang ◽  
Li Dong Chen
Keyword(s):  
Optical Properties ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Hall Coefficient ◽  
Hall Mobility ◽  
Room Temperature ◽  
Electrical And Optical Properties ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
P Type

A series of Cu1-xAlS2 (x = 0 ~ 0.08) bulk samples were synthesized by spark plasma sintering. The electrical and optical properties were investigated. P-type conductions for all samples were confirmed by both positive Seebeck coefficient and Hall coefficient. Bulk undoped CuAlS2 had a high conductivity of about 0.9 S/cm with a large band gap of 3.4 eV at room temperature. For vacancy-doped in Cu site, the carrier concentration was highly enhanced, reaching 1.7 × 1019 cm-3 for 8 mol% doped sample, and without decreasing the bang gap. The introduction of vacancies destroys the continuity of Cu-S network, which decreases the Hall mobility.

Effect of Cu doping on the electrical Properties of ZnTe by Vacuum Thermal Evaporation

2018 ◽  
Vol 31 (3) ◽  
pp. 20
Author(s):  
Sarmad M. M. Ali ◽  
Alia A.A. Shehab ◽  
Samir A. Maki
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Hall Effect ◽  
Carrier Concentration ◽  
Hall Mobility ◽  
Cu Doping ◽  
Before And After ◽  
Hall Effect Measurements ◽  
Evaporation Technique ◽  
P Type

In this study, the ZnTe thin films were deposited on a glass substrate at a thickness of 400nm using vacuum evaporation technique (2×10-5mbar) at RT. Electrical conductivity and Hall effect measurements have been investigated as a function of variation of the doping ratios (3,5,7%) of the Cu element on the thin ZnTe films. The temperature range of (25-200°C) is to record the electrical conductivity values. The results of the films have two types of transport mechanisms of free carriers with two values of activation energy (Ea1, Ea2), expect 3% Cu. The activation energy (Ea1) increased from 29meV to 157meV before and after doping (Cu at 5%) respectively. The results of Hall effect measurements of ZnTe , ZnTe:Cu films show that all films were (p-type), the carrier concentration (1.1×1020 m-3) , Hall mobility (0.464m2/V.s) for pure ZnTe film, increases the carrier concentration (6.3×1021m-3) Hall mobility (2m2/V.s) for doping (Cu at 3%) film, but  decreases by increasing Cu concentration.

High Temperature Thermoelectric Properies of LnPdX (Ln = lanthanide; X = Sb, Bi) Ternary Compounds

2005 ◽  
Vol 886 ◽  
Author(s):  
Takeyuki Sekimoto ◽  
Ken Kurosaki ◽  
Hiroaki Muta ◽  
Shinsuke Yamanaka
Keyword(s):  
Band Gap ◽  
Room Temperature ◽  
Band Gap Energy ◽  
Type Structure ◽  
Ternary Compounds ◽  
Plasma Sintering ◽  
Electrical Resistivities ◽  
Spark Plasma ◽  
Hall Effect Measurements ◽  
The Difference

ABSTRACTTernary compounds LnPdX (Ln = lanthanide elements of La, Gd, Er; X = Sb, Bi) were prepared by a spark plasma sintering (SPS) technique. The crystal structure of LaPdSb and GdPdSb was confirmed to be a hexagonal ZrBeSi-type structure and different from the other compounds with a MgAgAs-type structure. The electrical resistivities ρ of LaPdSb and GdPdSb indicate the metallic or semimetallic characteristics, while those of ErPdSb and LnPdBi indicate semiconductor characteristics. From the ln ρ − 1/T plot, the band gap energies Eg were estimated to be 0.28, 0.053, 0.081, and 0.049 eV for ErPdSb, LaPdBi, GdPdBi, and ErPdBi, respectively. All the samples have positive thermoelectric powers S above room temperature. The largest power factor S2/ρ was obtained as 49.5 μW/K2 cm at 327 K for LaPdSb. From the Hall effect measurements on ErPdX, the carrier concentration n of ErPdSb and ErPdBi were obtained as 5.9×1018 and 3.21×1019 cm−3 at room temperature, respectively. It is considered that the difference of n at room temperature is mainly due to the magnitude of the band gap energy.

scholarly journals Enhanced room-temperature thermoelectric performance of p-type BiSbTe by reducing carrier concentration

RSC Advances ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 2252-2257 ◽  
Author(s):  
Zichen Wei ◽  
Yang Yang ◽  
Chenyang Wang ◽  
Zhili Li ◽  
Lixian Zheng ◽  
...  
Keyword(s):  
Carrier Concentration ◽  
Room Temperature ◽  
Thermoelectric Performance ◽  
Alloy Effect ◽  
Ti Substitution ◽  
P Type

Ti substitution leads to enhanced thermoelectric performance of p-type Bi0.5Sb1.5Te3 due to carrier concentration regulation, alloy effect and anisotropic microstructure.

X-ray powder diffraction study of cesium ammonium hexachlorotellurate [Cs0.86(NH4)0.14]2TeCl6

2006 ◽  
Vol 21 (3) ◽  
pp. 225-228 ◽  
Author(s):  
R. Karray ◽  
A. Kabadou ◽  
A. Ben Salah ◽  
A. van der Lee
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Related Compound ◽  
Room Temperature ◽  
Diffraction Method ◽  
Large Family ◽  
Lattice Parameter ◽  
X Ray ◽  
Ammonium Group ◽  
Ir Spectroscopic

The crystal structure of cesium ammonium hexachlorotellurate [Cs0.86(NH4)0.14]2TeCl6, has been determined using X-ray powder diffraction techniques. At room temperature, the title compound crystallizes in the cubic space group Fm3m, with a lattice parameter a=10.470(17) Å. The Rietveld refinement of the structure led to final confidence factors Rp=0.0338 and Rwp=0.0487. The structure of [Cs0.86(NH4)0.14]2TeCl6 belongs to the large family of K2PtCl6-related structures. The H atoms of the ammonium group are orientated with its apex toward Te atoms as seen in the related compound (NH4)2SiF6. An IR spectroscopic study was performed to confirm the results of the diffraction method, notably concerning the presence of the ammonium group.

Mbe-Growth of InAs and GaSb Epitaxial Layers on GaAs Substrates

1989 ◽  
Vol 145 ◽  
Author(s):  
J. R. Söderström ◽  
D.H. Chow ◽  
T.C. McGill ◽  
T.J. Watson
Keyword(s):  
Hall Effect ◽  
Carrier Concentration ◽  
Growth Parameters ◽  
Hole Mobility ◽  
Extensive Study ◽  
Semiconductor Films ◽  
Mbe Growth ◽  
Gaas Substrates ◽  
Hall Effect Measurements ◽  
P Type

AbstractWe have grown a number of InAs and GaSb bulk layers on GaAs substrates and studied the properties of the semiconductor films as a function of the various growth parameters. Preliminary results from GaSb growth are presented in addition to an extensive study of InAs growth. The films were characterized during growth by RHEED. RHEED-oscillations were observed during both InAs and GaSb growths. Hall effect measurements yielded peak electron mobilities for InAs of 18,900 cm2/Vs at 300 K and 35,000 cm2/Vs at 77 K. For GaSb the as grown layers were found to be p-type with a carrier concentration of 9x1015cm-3 and a hole mobility of 910 cm2 /Vs at 300 K.

Thermoelectric Properties of Zn4-xSb3 with x=0~0.5

2007 ◽  
Vol 124-126 ◽  
pp. 1019-1022 ◽  
Author(s):  
K.W. Jang ◽  
Il Ho Kim ◽  
Jung Il Lee ◽  
Good Sun Choi
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Temperature Dependence ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Hall Mobility ◽  
Room Temperature ◽  
Vacuum Melting ◽  
Increasing Temperature

Non-stoichiometric Zn4-xSb3 compounds with x=0~0.5 were prepared by vacuum melting at 1173K and annealing solidified ingots at 623K. Electrical resistivity and Seebeck coefficient at 450K increased from 1.8cm and 145K-1 for Zn4Sb3(x=0) to 56.2cm 350K-1 for Zn3.5Sb3(x=0.5) due to the decrease of the carrier concentration. Hall mobility and carrier concentration was 31.5cm2V-1s-1 and 1.32X1020cm-3 for Zn4Sb3 and 70cm2V-1s-1 and 2.80X1018cm-3 for Zn3.5Sb3. Electrical resistivity of Zn4-xSb3 with x=0~0.2 showed linearly increasing temperature dependence, whereas those of Zn4-xSb3 with x=0.3~0.5 above 450 K tended to decrease. Thermal conductivity of Zn4Sb3 was 8.5mWcm-1K-1 at room temperature and that of Zn4-xSb3 with x≥0.3 was around 11mWcm-1K-1. Maximum ZT of Zn4Sb3 was obtained around 1.3 at 600K. Zn4Sb3 with x=0.3~0.5 showed very small value of ZT=0.2~0.3.

Dependence of structural, electrical, and optical properties of ZnO:Al films on substrate temperature

2001 ◽  
Vol 16 (7) ◽  
pp. 2118-2123 ◽  
Author(s):  
M. Chen ◽  
Z. L. Pei ◽  
X. Wang ◽  
C. Sun ◽  
L. S. Wen
Keyword(s):  
Optical Properties ◽  
Carrier Concentration ◽  
Hall Mobility ◽  
Room Temperature ◽  
Fused Silica ◽  
Electrical And Optical Properties ◽  
Al Content ◽  
Visible Transmittance ◽  
Dc Magnetron Reactive Sputtering ◽  
Increasing Temperature

ZnO:Al (ZAO) films were deposited on fused silica substrates heated to 350 °C by dc magnetron reactive sputtering from a Zn target mixed with 1.5 wt% Al. Films deposited on a substrate heated to a temperature between room temperature and 300 °C were (001)-oriented crystals, but those grown at 350 °C consisted of crystallites with (001) and (101) orientations. The dependence of electrical properties such as resistivity, carrier concentration, and Hall mobility on temperature was measured. The results indicate that the carrier concentration and Hall mobility increase with increasing temperature up to 250 °C, though the Al content remains unchanged in this temperature range. The probable mechanisms are discussed. The minimum resistivity of ZAO films is 4.23 × 10−4 Ω cm, with a carrier concentration of 9.21 × 1020 cm−3 and a Hall mobility of 16.0 cm2 v−1 s−1. The films show a visible transmittance of above 80%.

scholarly journals Optimal Carrier Concentration for High Thermoelectric Performance of Lead Substituted Bismuth Telluride in p-Type Doping

2018 ◽  
Vol 28 (2) ◽  
pp. 169
Author(s):  
Van Quang Tran
Keyword(s):  
Carrier Concentration ◽  
Thermoelectric Materials ◽  
Density Functional ◽  
Room Temperature ◽  
Density Functional Theory Calculation ◽  
Binary Compound ◽  
Thermoelectric Performance ◽  
Boltzmann Transport ◽  
Relaxation Time Approximation ◽  
P Type

Bi\(_{2}\)Te\(_{3}\) and its alloys are the well-known state-of-the-art thermoelectric materials operating at around room temperature. With lead substituted, the newly formed quasi-binary compound PbBi\(_{4}\)Te\(_{7}\), shows relatively high electrical conductivity and Seebeck coefficient. In this report, we employed the solution of the Boltzmann Transport Equation in a constant relaxation-time approximation within a first-principles density-functional-theory calculation to explore the role of the electronic thermal conductivity, \(\kappa _{e}\), on the thermoelectric performance of the compound with p-type doping. Results show that \(\kappa _{e}\) increases drastically with the increases of both temperature and carrier concentration. Even the power factor has been found to be markedly improved with the increase of the carrier concentration, a rapid increase of \(\kappa _{e}\) emerges as a big hindrance to improve the dimensionless figure of merit, ZT, of the compound. This is responsible for the limit of ZT. The larger ZT is found in low temperatures and carrier concentrations. The highest ZT of about 0.48 occurs at 223 K and at the carrier concentration of \(6\times 10^{17}\)cm\(^{ - 3}\). At room temperature the maximum ZT is slightly smaller. We demonstrated that at a particular temperature to maximize the thermoelectric performance of the compound, the carrier concentration must be optimized. Results show that the compound with p-type doping is a promising thermoelectric materials operating at around room temperature.

Calculation of intrinsic carrier concentration in tellurium taking anisotropy into account

1976 ◽  
Vol 54 (9) ◽  
pp. 967-969 ◽  
Author(s):  
C. H. Champness
Keyword(s):  
Electrical Conductivity ◽  
Carrier Concentration ◽  
Hall Coefficient ◽  
Room Temperature ◽  
Intrinsic Carrier Concentration ◽  
Transverse Magnetoresistance

The intrinsic carrier concentration in tellurium is calculated at room temperature from measured values of electrical conductivity, Hall coefficient, and transverse magnetoresistance, taking anisotropy into account in a simple way. The model assumes one value of mobility parallel and another perpendicular to the c axis for both the electrons and holes.

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