Valence band engineering and thermoelectric performance optimization in SnTe by Mn-alloying via a zone-melting method

2015 ◽  
Vol 3 (39) ◽  
pp. 19974-19979 ◽  
Author(s):  
Jun He ◽  
Xiaojian Tan ◽  
Jingtao Xu ◽  
Guo-Qiang Liu ◽  
Hezhu Shao ◽  
...  
Keyword(s):  
Seebeck Coefficient ◽  
Band Gap ◽  
Performance Optimization ◽  
Heavy Hole ◽  
Zone Melting ◽  
Energy Separation ◽  
Melting Method ◽  
Band Engineering ◽  
Valence Bands ◽  
P Type

Mn alloying in SnTe increases the band gap and decreases the energy separation between the light and heavy hole valence bands, leading to a significant enhancement in the Seebeck coefficient. The maximum ZT of ~1.25 is found at 920 K for p-type SnMn0.07Te.

Thermoelectric Properties of n-type (Bi2Se3)x(Bi2Te3)1-x Crystals Prepared by Zone Melting

2008 ◽  
Vol 368-372 ◽  
pp. 547-549
Author(s):  
Jun Jiang ◽  
Ya Li Li ◽  
Gao Jie Xu ◽  
Ping Cui ◽  
Li Dong Chen
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Zone Melting ◽  
Chemical Compositions ◽  
Melting Method ◽  
Temperature Range

In the present study, n-type (Bi2Se3)x(Bi2Te3)1-x crystals with various chemical compositions were fabricated by the zone melting method. Thermoelectric properties, including Seebeck coefficient (α), electrical conductivity (σ) and thermal conductivity (κ), were measured in the temperature range of 300-500 K. The influence of the variations of Bi2Te3 and Bi2Se3 content on thermoelectric properties was studied. The increase of Bi2Se3 content (x) caused an increase in carrier concentration and thus an increase of σ and a decrease of α. The maximum figure of merit (ZT = α2σT/κ) of 0.87 was obtained at about 325 K for the composition of 93%Bi2Te3-7%Bi2Se3 with doping TeI4.

High thermoelectric efficiency in co-doped degenerate p-type PbTe

2010 ◽  
Vol 1267 ◽  
Author(s):  
Ioannis Androulakis ◽  
Ilyia Todorov ◽  
Duck Young Chung ◽  
Sedat Ballikaya ◽  
Guoyu Wang ◽  
...  
Keyword(s):  
Heavy Hole ◽  
Elevated Temperatures ◽  
Resonant State ◽  
Band Model ◽  
Hole Density ◽  
Thermoelectric Efficiency ◽  
Na Substitution ◽  
Valence Bands ◽  
P Type ◽  
Two Band Model

AbstractWe explored the effect of K and K-Na substitution for Pb atoms in the lattice of PbTe, in an effort to test a hypothesis for the development of a resonant state that may enhance the thermoelectric power. At 300K the data can adequately be explained by a combination of a single and two-band model for the valence band of PbTe depending on hole density that varies in the range 1-15 × 1019 cm-3. A change in scattering mechanism was observed in the temperature dependence of the electrical conductivity, σ, for samples concurrently doped with K and Na which results in significantly enhanced σ at elevated temperatures and hence power factors. Thermal conductivity data provide evidence of a strong interaction between the light- and the heavy-hole valence bands at least up to 500K. Figure of merits as high as 1.3 at 700K were measured as a result of the enhanced power factors.

An enhanced Seebeck coefficient and high thermoelectric performance in p-type In and Mg co-doped Sn1−xPbxTe via the co-adjuvant effect of the resonance level and heavy hole valence band

2017 ◽  
Vol 5 (23) ◽  
pp. 5737-5748 ◽  
Author(s):  
Subhajit Roychowdhury ◽  
U. Sandhya Shenoy ◽  
Umesh V. Waghmare ◽  
Kanishka Biswas
Keyword(s):  
Synergistic Effect ◽  
Seebeck Coefficient ◽  
Valence Band ◽  
Heavy Hole ◽  
Resonance Level ◽  
Thermoelectric Performance ◽  
Adjuvant Effect ◽  
P Type ◽  
Co Doped

Remarkable enhancement of the Seebeck coefficient of an Sn rich Sn1−xPbxTe system due to the synergistic effect of resonance level formation and valence band convergence.

scholarly journals Effects of Sintering Atmosphere on the Optical, Thermal and Electrical Properties of Inkjet Printed ZnxCu(1-x)Fe2O4 Thin Films

2021 ◽  
Vol 81 (2) ◽  
pp. 25-35
Author(s):  
Lim Joon Hoong
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Band Gap ◽  
Optical Band Gap ◽  
Electronic Band Structure ◽  
Copper Ferrite ◽  
Electronic Band ◽  
Sintering Atmosphere ◽  
P Type

The effects of sintering atmosphere on the optical, thermal and electric properties of inkjet printed ZnxCu(1-x)Fe2O4 thin films have been investigated. The thin film samples were sintered separately in vacuum and oxygen. The obtained samples were then characterized by X-ray diffraction (XRD), optical band gap, electrical conductivity, Seebeck coefficient and thermal conductivity. XRD analysis showed that the fabricated samples have a cubic spinel structure of zinc copper ferrite regardless of the sintering atmosphere. The electrical conductivity of ZnxCu(1-x)Fe2O4 thin films sintered in oxygen was about 5 % higher compared to ZnxCu(1-x)Fe2O4 thin films sintered in vacuum. The optical band gap shows that the samples sintered in oxygen had smaller band gap compared to samples sintered in vacuum. The electronic band structure simulated through ABINIT shows ZnxCu(1-x)Fe2O4 is an indirect band gap material. A smaller electronic band gap was observed in O2 rich condition and was in agreement with the optical band gap and electrical conductivity test results. Seebeck coefficient of ZnxCu(1-x)Fe2O4 thin films sintered in oxygen remained positive , confirming charge transport by hole carries as p-type semiconductors. A change from p-type to n-type semiconductors was observed when ZnxCu(1-x)Fe2O4 thin films sintered in vacuum.

Dislocation Structure, Electrical and Luminescent Properties of Hydrophilically Bonded Silicon Wafer Interface

2011 ◽  
Vol 178-179 ◽  
pp. 233-242 ◽  
Author(s):  
Anton Bondarenko ◽  
Oleg Vyvenko ◽  
Iliya Kolevatov ◽  
Ivan Isakov ◽  
Oleg Kononchuk
Keyword(s):  
Activation Energy ◽  
Band Gap ◽  
Thermal Activation ◽  
Electronic States ◽  
Luminescent Properties ◽  
Thermal Activation Energy ◽  
Enhanced Luminescence ◽  
Valence Bands ◽  
P Type ◽  
Dislocation Related Luminescence

The dislocation-related luminescence (DRL) in the vicinity of D1 band (0.8 eV) in hydrophilically bonded n- and p-type silicon wafers is investigated by means of recently developed pulsed trap refilling enhanced luminescence technique (Pulsed-TREL). The shallow and deep dislocation related electronic states in both upper and lower part of the band gap are determined and characterized by means of DLTS. Among those traps we have established ones which directly participate in D1 DRL. We have shown that D1 luminescence goes via shallow dislocation related states (SDRS) located close to the conduction and valence bands with thermal activation energy of about 0.1 eV whereas deep levels do not participate in D1 DRL. The model explaining the fact how the 0.8 eV luminescence may go through levels which interlevel energy is at least 0.97 eV in terms of Coulomb interaction between ionized SDRS is suggested.

THERMOELECTRIC PROPERTIES OF Bi2Te3–Sb2Te3 ALLOYS

1965 ◽  
Vol 43 (4) ◽  
pp. 653-669 ◽  
Author(s):  
C. H. Champness ◽  
P. T. Chiang ◽  
P. Parekh
Keyword(s):  
Entire Range ◽  
Figure Of Merit ◽  
Hole Concentration ◽  
Zone Melting ◽  
Nominal Composition ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Antimony Content ◽  
Melting Method ◽  
P Type

Alloys of nominal composition Bi2−xSbxTe3+y were prepared in an evacuated, sealed ampule by a horizontal zone melting method. Single-crystal samples were cut from the ingots, and measurements of Seebeck coefficient, electrical conductivity, thermoelectric figure of merit (Z), and thermal conductivity (κ) were made over a temperature range of 160 to 360 °K using the Peltier–Seebeck method developed by Harman. Alloys of nominal composition Bi2−xSbxTe3.13 were found to be n type for [Formula: see text] and p type for x > 1. In alloys of high antimony content, the hole concentration was influenced very little by the amount of excess tellurium. The change of Z was studied by varying y from 0.06 to 0.26 at x equal to 0, 0.25, 1.4, 1.5, and 1.6 respectively. Optimum doping to maximize Z did not appear to be possible in a simple way over the entire range of x between 0 and 2. The temperature dependence of κ indicated that the maximum Z at x = 1.5 may be limited by an ambipolar contribution.

Band Engineering and Thermoelectric Performance Optimization of p-Type GeTe-Based Alloys through Ti/Sb Co-Doping

2020 ◽  
Vol 124 (10) ◽  
pp. 5583-5590 ◽  
Author(s):  
Luo Yue ◽  
Wenlin Cui ◽  
Shuqi Zheng ◽  
Yue Wu ◽  
Lijun Wang ◽  
...  
Keyword(s):  
Performance Optimization ◽  
Thermoelectric Performance ◽  
Band Engineering ◽  
Co Doping ◽  
P Type

scholarly journals Detrimental Effects of Doping Al and Ba on the Thermoelectric Performance of GeTe

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2237 ◽  
Author(s):  
Bhuvanesh Srinivasan ◽  
Alain Gellé ◽  
Jean-François Halet ◽  
Catherine Boussard-Pledel ◽  
Bruno Bureau
Keyword(s):  
Carrier Mobility ◽  
Figure Of Merit ◽  
Charge Carrier Concentration ◽  
Energy Separation ◽  
Thermoelectric Figure ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Higher Temperature ◽  
Valence Bands ◽  
P Type

GeTe-based materials are emerging as viable alternatives to toxic PbTe-based thermoelectric materials. In order to evaluate the suitability of Al as dopant in thermoelectric GeTe, a systematic study of thermoelectric properties of Ge1−xAlxTe (x = 0–0.08) alloys processed by Spark Plasma Sintering are presented here. Being isoelectronic to Ge1−xInxTe and Ge1−xGaxTe, which were reported with improved thermoelectric performances in the past, the Ge1−xAlxTe system is particularly focused (studied both experimentally and theoretically). Our results indicate that doping of Al to GeTe causes multiple effects: (i) increase in p-type charge carrier concentration; (ii) decrease in carrier mobility; (iii) reduction in thermopower and power factor; and (iv) suppression of thermal conductivity only at room temperature and not much significant change at higher temperature. First principles calculations reveal that Al-doping increases the energy separation between the two valence bands (loss of band convergence) in GeTe. These factors contribute for Ge1−xAlxTe to exhibit a reduced thermoelectric figure of merit, unlike its In and Ga congeners. Additionally, divalent Ba-doping [Ge1−xBaxTe (x = 0–0.06)] is also studied.

Conduction bands of GaxIn1–x Sb alloys

1969 ◽  
Vol 47 (22) ◽  
pp. 2553-2564 ◽  
Author(s):  
William M. Coderre ◽  
John C. Woolley
Keyword(s):  
Electrical Conductivity ◽  
Band Gap ◽  
Hall Coefficient ◽  
Solidus Temperature ◽  
Energy Separation ◽  
Trial And Error ◽  
Unknown Parameters ◽  
Alloy Scattering ◽  
Conduction Bands ◽  
Valence Bands

Measurements of Hall coefficient and electrical conductivity have been made on alloys of the system GaxIn1–xSb over a range of temperature from 100 °K up to 950 °K or to 20° below the solidus temperature of the particular specimen, whichever was the lower. These data have then been analyzed in terms of equations involving three conduction and two valence bands, the important unknown parameters in the equations being determined by a trial and error fitting technique. The results give the variation of the energy separation from the valence band of the [Formula: see text] and [Formula: see text] conduction band minima, as well as the main (000) band gap as a function of the composition and temperature. Also determined from the analysis are the (000) electron mobilities, which are found to vary linearly with composition, indicating that alloy scattering has negligible effect on the mobility values.

Intraband Absorption in P-Type InGaAs at FIR Frequencies

1993 ◽  
Vol 329 ◽  
Author(s):  
Xiangkun Zhang ◽  
Phengpiao Liao ◽  
Ali Afzali-Kushaa ◽  
George I. Haddad
Keyword(s):  
Absorption Coefficient ◽  
Doping Concentration ◽  
Heavy Hole ◽  
Incident Radiation ◽  
Intraband Absorption ◽  
Valence Bands ◽  
P Type

AbstractIntraband absorption in p-type In.53Ga.47 As has been measured at FIR frequencies (40–240 cm−1). It is found that the absorption in p-type InGaAs, which is associated with transitions between the light- and heavy-hole valence bands, is very strong. The absorption coefficient is as high as 103–104 cm−1. It increases with the doping concentration but decreases with the frequency of the incident radiation and temperature.

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