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1.
L. N. Lukyanova V. A. Kutasov P. P. Konstantinov V. V. Popov 《Journal of Electronic Materials》2010,39(9):2070-2073
Thermoelectric and galvanomagnetic properties of p-type solid solutions based on bismuth and antimony chalcogenides (Bi,Sb)2(Te,Se)3 have been studied to analyze the features of the figure of merit Z. The increase of Z and ZT for the p-Bi2−x
Sb
x
Te3 composition at x = 1.6 in the temperature interval of 370 K to 550 K was shown to be defined by the increase of the density-of-states effective
mass, the slope of the temperature dependence of the carrier mobility, and the reduction of the lattice thermal conductivity
for optimal charge carrier concentration. High carrier mobility and low lattice thermal conductivity provide the increase
of Z and ZT in the p-Bi2−x
Sb
x
Te3−y
Se
y
(x = 1.3, y = 0.06) solid solution in the interval from 300 K to 370 K. The growth of Z in these compositions is determined by the increase of the compression of the constant-energy ellipsoids along binary and
bisector directions, and by the change of the tilt angle Θ between the principal axes of the ellipsoids and the crystallographic
axes. 相似文献
2.
The best films for thermoelectric applications near room temperature are based on the compounds Bi2Te3, Sb2Te3, and Bi2Se3, which as single crystals have distinct anisotropy in their electrical conductivity σ regarding the trigonal c-axis, whereas the Seebeck coefficient S is nearly isotropic. For p- and n-type alloys, P
⊥c > P
||c, and the power factors P
⊥c of single crystals are always higher compared with polycrystalline films, where the power factor is defined as P = S
2
σ, ⊥c and ||c are the direction perpendicular and parallel to the c-axis, respectively. For the first time in sputter-deposited
p-type (Bi0.15Sb0.85)2Te3 and n-type Bi2(Te0.9Se0.1)3 thin films, the anisotropy of the electrical conductivity has been measured directly as it depends on the angle φ between the electrical current and the preferential orientation of the polycrystals (texture) using a standard four-probe
method. The graphs of σ(φ) show the expected behavior, which can be described by a weighted mixture of σ
⊥c and σ
||c contributions. Because (σ
⊥c/σ
||c)
p
< (σ
⊥c/σ
||c)
n
, the n-type films have stronger anisotropy than the p-type films. For this reason, the angular weighted contributions of P
||c lead to a larger drop in the power factor of polycrystalline n-type films compared with p-type films. 相似文献
3.
Polycrystalline p-type Bi0.5Sb1.5Te3 and n-type Bi2Te2.7Se0.3 thermoelectric (TE) alloys containing a small amount (vol.% ≤5) of SiC nanoparticles were fabricated by mechanical alloying
and spark plasma sintering. It was revealed that the effects of SiC addition on TE properties can be different between p-type and n-type Bi2Te3-based alloys. SiC addition slightly increased the power factor of the p-type materials by decreasing both the electrical resistivity (ρ) and Seebeck coefficient (α), but decreased the power factor of n-type materials by increasing both ρ and α. Regardless of the conductivity type, the thermal conductivity was reduced by dispersing SiC nanoparticles in the Bi2Te3-based alloy matrix. As a result, a small amount (0.1 vol.%) of SiC addition increased the maximum dimensionless figure of
merit (ZT
max) of the p-type Bi0.5Sb1.5Te3 alloys from 0.88 for the SiC-free sample to 0.97 at 323 K, though no improvement in TE performance was obtained in the case
of n-type Bi2Te2.7Se0.3 alloys. Importantly, the SiC-dispersed alloys showed better mechanical properties, which can improve material machinability
and device reliability. 相似文献
4.
Thermoelectric materials are attractive since they can recover waste heat directly in the form of electricity. In this study,
the thermoelectric properties of ternary rare-earth sulfides LaGd1+x
S3 (x = 0.00 to 0.03) and SmGd1+x
S3 (x = 0.00 to 0.06) were investigated over the temperature range of 300 K to 953 K. These sulfides were prepared by CS2 sulfurization, and samples were consolidated by pressure-assisted sintering to obtain dense compacts. The sintered compacts
of LaGd1+x
S3 were n-type metal-like conductors with a thermal conductivity of less than 1.7 W K−1 m−1. Their thermoelectric figure of merit ZT was improved by tuning the chemical composition (self-doping). The optimized ZT value of 0.4 was obtained in LaGd1.02S3 at 953 K. The sintered compacts of SmGd1+x
S3 were n-type hopping conductors with a thermal conductivity of less than 0.8 W K−1 m−1. Their ZT value increased significantly with temperature. In SmGd1+x
S3, the ZT value of 0.3 was attained at 953 K. 相似文献
5.
Chia-Jyi Liu Gao-Jhih Liu Chun-Wei Tsao Yo-Jhih Huang 《Journal of Electronic Materials》2009,38(7):1499-1503
We report on the successful hydrothermal synthesis of Bi0.5Sb1.5Te3, using water as the solvent. The products of the hydrothermally prepared Bi0.5 Sb1.5Te3 were hexagonal platelets with edges of 200–1500 nm and thicknesses of 30–50 nm. Both the Seebeck coefficient and electrical
conductivity of the hydrothermally prepared Bi0.5Sb1.5Te3 were larger than those of the solvothermally prepared counterpart. Hall measurements of Bi0.5Sb1.5Te3 at room temperature indicated that the charge carrier was p-type, with a carrier concentration of 9.47 × 1018 cm−3 and 1.42 × 1019 cm−3 for the hydrothermally prepared Bi0.5Sb1.5Te3 and solvothermally prepared sample, respectively. The thermoelectric power factor at 290 K was 10.4 μW/cm K2 and 2.9 μW/cm K2 for the hydrothermally prepared Bi0.5Sb1.5Te3 and solvothermally prepared sample, respectively. 相似文献
6.
The effects of atomic hydrogen (H) and Br/methanol etching on Hg1−x
Cd
x
Te films were investigated using x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Exposure of an
as-received Hg1−x
Cd
x
Te sample to H + H2 resulted in H-induced TeO2 reduction. The oxide reduction was first order with respect to H + H2 exposure. Exposure to H + H2 after etching the Hg1−x
Cd
x
Te film in a Br/methanol solution induced Hg and C depletion. Hg and C removal was also observed after completely reducing
the TeO2 on the as-received sample. The removal process was hindered by the formation of a Cd-rich overlayer on both etched and unetched
surfaces. 相似文献
7.
A. O. Evwaraye 《Journal of Electronic Materials》2010,39(6):751-755
n-Type 4H-SiC bulk samples with a net doping concentration of 2.5 × 1017 cm−3 were irradiated at room temperature with 1-MeV electrons. The high doping concentration plus a reverse bias of up to −13 V
ensures high electric field in the depletion region. The dependence of the emission rate on the electric field in the depletion
region was measured using deep-level transient spectroscopy (DLTS) and double-correlation deep-level transient spectroscopy
(DDLTS). The experimental data are adequately described by the phonon-assisted tunneling model proposed by Karpus and Pere. 相似文献
8.
C. Candolfi J. Leszczynski P. Masschelein C. Chubilleau B. Lenoir A. Dauscher E. Guilmeau J. Hejtmanek S. J. Clarke R. I. Smith 《Journal of Electronic Materials》2010,39(9):2132-2135
Zintl phases are currently receiving great attention for their thermoelectric potential typified by the discovery of a high
ZT value in Yb14MnSb11-based compounds. Herein, we report on the crystallographic characterization via neutron and x-ray diffraction experiments,
and on the thermoelectric properties measured in the 300 K to 1000 K temperature range, of Mo3Sb7 and its isostructural compounds Mo3−x
Ru
x
Sb7. Even though Mo3Sb7 displays rather high ZT values given its metallic character, the partial substitution of Mo by Ru substantially improves its thermoelectric properties,
resulting in a ZT value of ∼0.45 at 1000 K for x = 0.8. 相似文献
9.
A. A. Lotin O. A. Novodvorsky E. V. Khaydukov V. N. Glebov V. V. Rocheva O. D. Khramova V. Ya. Panchenko C. Wenzel N. Trumpaicka K. D. Chtcherbachev 《Semiconductors》2010,44(2):246-250
The Mg
x
Zn1-x
O thin films with a Mg content corresponding to x = 0–0.45 are grown by pulsed laser deposition on ablation of ceramic targets. The conditions for epitaxial growth of the
films on the single-crystal Al2O3 (00.1) substrates are established. The record limit of solubility of Mg in hexagonal ZnO, x = 35 is attained. In this case, the lattice mismatch for the parameter a of the ZnO and Mg0.35Zn0.65O films does not exceed 1%, whereas the band gaps of the films differ by 0.78 eV. The surface roughness of the films corresponds
to 0.8–1.5 nm in the range of x = 0–0.27. 相似文献
10.
Ternary rare-earth sulfides NdGd1+x
S3, where 0 ≤ x ≤ 0.08, were prepared by sulfurizing Ln2O3 (Ln = Nd, Gd) with CS2 gas, followed by reaction sintering. The sintered samples have full density and homogeneous compositions. The Seebeck coefficient,
electrical resistivity, and thermal conductivity were measured over the temperature range of 300 K to 950 K. All the sintered
samples exhibit a negative Seebeck coefficient. The magnitude of the Seebeck coefficient and the electrical resistivity decrease
systematically with increasing Gd content. The thermal conductivity of all the sintered samples is less than 1.9 W K−1 m−1. The highest figure of merit ZT of 0.51 was found in NdGd1.02S3 at 950 K. 相似文献
11.
N. A. Vlasenko N. V. Sopinskii E. G. Gule V. V. Strelchuk P. F. Oleksenko L. I. Veligura A. S. Nikolenko M. A. Mukhlyo 《Semiconductors》2012,46(3):323-329
The photoluminescence of SiO
x
films deposited on c-Si wafers by the thermal evaporation of SiO in a vacuum and, for the first time, doped with ErF3 by coevaporation is studied. It is shown that, like undoped SiO
x
films, the unannealed SiO
x
:ErF3 films passivate the surface of the Si wafers and, thus, increase their edge photoluminescence intensity almost fivefold.
A similar increase is observed after annealing of the doped films in air at 750°C. Doping with ErF3 suppresses the photoluminescence of Si nanoclusters, if the films have been subjected to high-temperature annealing (at 750°C).
In this case, the PL intensity of the band with a peak at ∼890 nm decreases as well. The ∼890 nm band is observed for the
first time and, due to its features, is attributed to transitions in SiO
x
matrix defects. The experimentally observed effect of ErF3 doping on SiO
x
film photoluminescence is interpreted. An intense photoluminescence signal from Er3+ ions in the nearinfrared spectral region (the 4
I
11/2 → 4
I
15/2 and 4
I
13/2 → 4
I
15/2 transitions) is observed in the SiO
x
:ErF3 films annealed in air at 750°C. This finding shows that 1.54 μm luminescent emitters, which are currently in popular demand,
can be produced by a simple low-cost method. 相似文献
12.
Shufen Fan Junnan Zhao Qingyu Yan Jan Ma Huey Hoon Hng 《Journal of Electronic Materials》2011,40(5):1018-1023
n-Type Bi2Te3 nanocomposites with enhanced figure of merit, ZT, were fabricated by a simple, high-throughput method of mixing nanostructured Bi2Te3 particles obtained through melt spinning with micron-sized particles. Moderately high power factors were retained, while
the thermal conductivity of the nanocomposites was found to decrease with increasing weight percent of nanoinclusions. The
peak ZT values for all the nanocomposites were above 1.1, and the maximum shifted to higher temperature with increasing amount of
nanoinclusions. A maximum ZT of 1.18 at 42°C was obtained for the 10 wt.% nanocomposite, which is a 43% increase over the bulk sample at the same temperature.
This is the highest ZT reported for n-type Bi2Te3 binary material, and higher ZT values are expected if state-of-the-art Bi2Te3−x
Se
x
materials are used. 相似文献
13.
Tae-Sung Oh 《Journal of Electronic Materials》2009,38(7):1041-1047
The p-type (Bi,Sb)2Te3/(Pb,Sn)Te functional gradient materials (FGMs) were fabricated by hot-pressing mechanically alloyed (Bi0.2Sb0.8)2Te3 and 0.5 at.% Na2Te-doped (Pb0.7Sn0.3)Te powders together at 500°C for 1 h in vacuum. Segment ratios of (Bi,Sb)2Te3 to (Pb,Sn)Te were varied as 3:1, 1.3:1, and 1:1.6. A reaction layer of about 350-μm thickness was formed at the (Bi,Sb)2Te3/(Pb,Sn)Te FGM interface. Under temperature differences larger than 340°C applied across a specimen, superior figures of merit
were predicted for the (Bi,Sb)2Te3/(Pb,Sn)Te FGMs to those of (Bi0.2Sb0.8)2Te3 and (Pb0.7Sn0.3)Te. With a temperature difference of 320°C applied across a specimen, the (Bi,Sb)2Te3/(Pb,Sn)Te FGMs with segment ratios of 3:1 and 1.3:1 exhibited the maximum output powers of 72.1 mW and 72.6 mW, respectively,
larger than the 63.9 mW of (Bi0.2Sb0.8)2Te3 and the 26 mW of 0.5 at.% Na2Te-doped (Pb0.7Sn0.3)Te. 相似文献
14.
The electrochemical behavior of nonaqueous dimethyl sulfoxide solutions of BiIII, TeIV, and SbIII was investigated using cyclic voltammetry. On this basis, Bi
x
Sb2−x
Te
y
thermoelectric films were prepared by the potentiodynamic electrodeposition technique in nonaqueous dimethyl sulfoxide solution,
and the composition, structure, morphology, and thermoelectric properties of the films were analyzed. Bi
x
Sb2−x
Te
y
thermoelectric films prepared under different potential ranges all possessed a smooth morphology. After annealing treatment
at 200°C under N2 protection for 4 h, all deposited films showed p-type semiconductor properties, and their resistances all decreased to 0.04 Ω to 0.05 Ω. The Bi0.49Sb1.53Te2.98 thermoelectric film, which most closely approaches the stoichiometry of Bi0.5Sb1.5Te3, possessed the highest Seebeck coefficient (85 μV/K) and can be obtained under potentials of −200 mV to −400 mV. 相似文献
15.
Reflectance spectra of single crystals of Bi2Te3-Sb2Te3 solid solutions containing 0, 10, 25, 40, 50, 60, 65, 70, 80, 90, 99.5, and 100 mol % of Sb2Te3 have been studied in the range of 400–4000 cm−1 at the temperature T = 291 K and with orientation of the vector of the electric-field strength E perpendicular to the trigonal axis of the crystal C
3 (E ⊥ C
3). The shape of the spectra is characteristic of plasma reflection; the spectra include the features in the range 1250–3000
cm−1 corresponding to the optical band gap E
g opt. The features become more pronounced as the content of Bi2Te3 is increased to 80 mol % in the composition of the Bi2Te3-Sb2Te3 solid solution. A further increase in the content of Sb2Te3 is accompanied by discontinuities in the functional dependences of the parameters characterizing the plasma oscillations
of free charge carriers on the solid-solution composition and also by a sharp increase in E
g opt. 相似文献
16.
M. N. Solovan A. I. Mostovyi V. V. Brus E. V. Maistruk P. D. Maryanchuk 《Semiconductors》2016,50(8):1020-1024
n-TiN/p-Hg3In2Te6 heterostructures are fabricated by depositing a thin n-type titanium nitride (TiN) film onto prepared p-type Hg3In2Te6 plates using reactive magnetron sputtering. Their electrical and photoelectric properties are studied. Dominant charge-transport mechanisms under forward bias are analyzed within tunneling-recombination and tunneling models. The fabricated n-TiN/p-Hg3In2Te6 structures have the following photoelectric parameters at an illumination intensity of 80 mW/cm2: the open-circuit voltage is VOC = 0.52 V, the short-circuit current is ISC = 0.265 mA/cm2, and the fill factor is FF = 0.39. 相似文献
17.
A. A. Lebedev V. V. Kozlovski S. V. Belov E. V. Bogdanova G. A. Oganesyan 《Semiconductors》2011,45(9):1145-1147
Carrier removal rate (V
d
) in p-6H-SiC in its irradiation with 8-MeV protons has been studied. The p-6H-SiC samples were produced by sublimation in vacuum. V
d
was determined by analysis of capacitance-voltage characteristics and from results of Hall effect measurements. It was found
that complete compensation of samples with initial value of N
a
− N
d
≈ 1.5 × 1018 cm−3 occurs at an irradiation dose of ∼1.1 × 1016 cm−2. In this case, the carrier removal rate was ∼130 cm−1. 相似文献
18.
We report a sol–gel method to deposit a high-k dielectric, zirconium oxide (ZrO2). This solution-based approach has advantages of easy processing and low fabrication cost. Effects of annealing temperatures
on dielectric properties, such as tunneling current density and capacitance density, are reported. Morphological and chemical
characterizations suggest that the process temperature can be kept at or below 300°C. We have employed the solution-processed
ZrO2 dielectric in a zinc tin oxide thin-film transistor. Saturation mobility of 4.0 cm2/V s at operating voltage of 2 V has been observed. The measured subthreshold swing is 74 mV/decade, which is the result of
the combination of an electronically clean dielectric/semiconductor interface and high insulator capacitance. 相似文献
19.
V. G. Baru S. Bayliss V. A. Zhitov L. Yu. Zakharov G. Kartopu V. I. Pokalyakin A. Sapelkin G. V. Stepanov A. A. Timofeev O. F. Shevchenko 《Russian Microelectronics》2005,34(5):272-278
With a view to creating Si LEDs, the structural and luminescent properties of SiO x N y films containing Si nanocrystals in the SiO x N y matrix are studied experimentally. It is found that the film structure (nanocrystal size and concentration, the presence of an amorphous phase, etc.) and the spectrum and intensity of photoluminescence (PL) and electroluminescence (EL) are strongly dependent on the Si stoichiometric excess δ and annealing conditions. At δ≈ 10%, unannealed films are amorphous and contain Si clusters of size < 2 nm, as deduced from the TEM and microdiffraction data obtained. Annealing at 800–1000°C for 10–60 min produces Si crystals 3–5 nm in size with a concentration of ≈1018 cm?3. The annealed films exhibit room-temperature PL and EL over the wavelength range 400–850 nm with intensity peaks located at 50–60 and 60–70 nm, respectively. The PL and EL spectra are found to be qualitatively similar. This suggests that both the PL and the EL should be associated with the formation of luminescent centers at nanocrystal–matrix interfaces and in boundary regions. However, the two phenomena should differ in the mechanism by which the centers are excited. With the EL, excitation should occur by impact processes due to carrier heating in high electric fields. It is found that as δ increases, so does the proportion of large amorphous Si clusters with a high density of dangling bonds. This enhances nonradiative recombination and suppresses luminescence. 相似文献
20.
P. A. Ivanov A. S. Potapov T. P. Samsonova O. Korol’kov N. Sleptsuk 《Semiconductors》2011,45(10):1306-1310
Deep-level transient spectroscopy (DLTS) has been used to study p-n junctions fabricated by implantation of boron into epitaxial 4H-SiC films with n-type conductivity and the donor concentration (8–9) × 1014 cm−3. A DLTS signal anomalous in sign is observed; this signal is related to recharging of deep compensating boron-involved centers
in the n-type region near the metallurgical boundary of the p-n junction. 相似文献