Broad temperature plateau for high ZTs in heavily doped p-type SnSe single crystals

2016 ◽  
Vol 9 (2) ◽  
pp. 454-460 ◽  
Author(s):  
Kunling Peng ◽  
Xu Lu ◽  
Heng Zhan ◽  
Si Hui ◽  
Xiaodan Tang ◽  
...  
Keyword(s):  
Fermi Level ◽  
Single Crystal ◽  
Single Crystals ◽  
Carrier Concentration ◽  
Heavily Doped ◽  
P Type ◽  
Temperature Plateau

The increased number of carrier pockets near the Fermi level and the optimized carrier concentration in doped SnSe single crystal can lead to a high averageZTave∼ 1.2 from 300 K to 800 K and a peakZTmaxvalue in excess of 2.0 at 800 K along the crystallographicb-axis.

Electrical Transport Properties of the Pentatelluride Materials Hfte5 and Zrte5

1997 ◽  
Vol 478 ◽  
Author(s):  
T. M. Tritt ◽  
M. L. Wilson ◽  
R. L. Littleton ◽  
C. Feger ◽  
J. Kolis ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Electrical Transport ◽  
Entire Range ◽  
Room Temperature ◽  
Polycrystalline Material ◽  
Polycrystalline Materials ◽  
Electrical Transport Properties ◽  
Low Dimensional ◽  
P Type

AbstractWe have measured the resistivity and thermopower of single crystals as well as polycrystalline pressed powders of the low-dimensional pentatelluride materials: HfTe5 and ZrTe5. We have performed these measurements as a function of temperature between 5K and 320K. In the single crystals there is a peak in the resistivity for both materials at a peak temperature, Tp where Tp ≈ 80K for HfTe5 and Tp ≈ 145K for ZrTe5. Both materials exhibit a large p-type thermopower around room temperature which undergoes a change to n-type below the peak. This data is similar to behavior observed previously in these materials. We have also synthesized pressed powders of polycrystalline pentatelluride materials, HfTe5 and ZrTe5. We have measured the resistivity and thermopower of these polycrystalline materials as a function of temperature between 5K and 320K. For the polycrystalline material, the room temperature thermopower for each of these materials is relatively high, +95 μV/K and +65 μV/K for HfTe5 and ZrTe5 respectively. These values compare closely to thermopower values for single crystals of these materials. At 77 K, the thermopower is +55 μV/K for HfTe5 and +35 μV/K for ZrTe5. In fact, the thermopower for the polycrystals decreases monotonically with temperature to T ≈ 5K, thus exhibiting p-type behavior over the entire range of temperature. As expected, the resistivity for the polycrystals is higher than the single crystal material, with values of 430 mΩ-cm and 24 mΩ-cm for Hfre5 and ZrTe5 respectively, compared to single crystal values of 0.35 mΩ-cm (HfTe5) and 1.0 mΩ-cm (ZrTe5). We have found that the peak in the resistivity evident in both single crystal materials is absent in these polycrystalline materials. We will discuss these materials in relation to their potential as candidates for thermoelectric applications.

The Nucleation of Crystalline TiSi2 Phases from Amorphous TiSix Layers and Interfacial Layers

1996 ◽  
Vol 441 ◽  
Author(s):  
R. T. Tung ◽  
K. Fujii ◽  
K. Kikuta ◽  
S. Chikaki ◽  
T. Kikkawa
Keyword(s):  
Single Crystal ◽  
Transformation Temperature ◽  
Interfacial Layers ◽  
Heavily Doped ◽  
Amorphous Si ◽  
P Type

AbstractSilicide reaction between co-deposited TiSix layers and Si was studied. It was shown that an amorphous TiSix layer, with x − 0.5–1, deposited between amorphous Si and the Ti film led to a significant reduction in the observed C49→C54 TiSis transformation temperature. Amorphous TiSix layers generated by the pre-deposition of Ti and pre-annealing also enhanced the nucleation of the C54-TiSi2 phase. The efficacy of the interfacial TiSix layer was demonstrated on undoped and heavily doped n- and p-type α-Si, but was found to be absent on single crystal Si. Possible mechanisms of these phenomena are discussed.

scholarly journals Solution growth of chalcopyrite Cu(In1−x Ga x )Se2 single crystals for high open-circuit voltage photovoltaic device

2021 ◽  
Vol 40 (1) ◽  
pp. 439-445
Author(s):  
Akira Nagaoka ◽  
Yusuke Shigeeda ◽  
Kensuke Nishioka ◽  
Taizo Masuda ◽  
Kenji Yoshino
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Open Circuit Voltage ◽  
Secondary Phase ◽  
Open Circuit ◽  
Bulk Single Crystal ◽  
Fundamental Properties ◽  
Traveling Heater Method ◽  
Absorbing Layer ◽  
P Type

Abstract I–III–VI2 Chalcopyrite Cu(In1−x Ga x )Se2 (CIGS) has attracted attention as absorbing layer in photovoltaic (PV) device. In this study, we investigated the fundamental properties of CIGS single crystals, and fabricated single crystal-based PV device. CIGS single crystals without secondary phase were successfully grown by In-solvent traveling heater method (THM). The conversion of conduction type from n- to p-type can be observed above 0.3 of Ga ratio x because of high acceptor defect concentration. PV device based on high-quality CIGS bulk single crystal demonstrates high open-circuit voltage of 0.765 V with the efficiency of 12.6%.

Electrical Properties of Epitaxial Silicide-Silicon Interfaces

1985 ◽  
Vol 54 ◽  
Author(s):  
R. T. Tung ◽  
A. F. J. Levi ◽  
J. M. Gibson ◽  
K. K. Ng ◽  
A. Chantre
Keyword(s):  
Fermi Level ◽  
Single Crystal ◽  
Schottky Barrier ◽  
Surface Region ◽  
Ideal Behavior ◽  
Near Surface ◽  
Barrier Heights ◽  
Transmission Electron ◽  
Current Voltage ◽  
P Type

ABSTRACTThe Schottky barrier heights of single crystal NiSi2 layers on Si(111) have been studied by current-voltage, capacitance-voltage and activation energy techniques. Near ideal behavior is found for Schottky barriers grown on substrates cleaned at ∼820°C in ultrahigh vacuum. The Fermi level positions at the interfaces of single crystal type A and type B NiSi2 are shown to differ by ∼0.14 eV. Transmission electron microscopy demonstrated the epitaxial perfection of these suicide layers. At a cleaning temperature of 1050° C, the near surface region of lightly doped n-type Si was converted to p-type. The presence of a p-n junction was directly revealed by spreading resistance measurements and resulted in a high apparent Schottky barrier height (≥0.75 eV) which no longer bears immediate relationship to the interface Fermi level position.

Native Defects, Diffusion, Self-Compensation, and Boron Doping in Cubic Silicon Carbide

1989 ◽  
Vol 162 ◽  
Author(s):  
C. Wang ◽  
J. Bemholc ◽  
R. F. Davis
Keyword(s):  
Silicon Carbide ◽  
Fermi Level ◽  
Theoretical Investigation ◽  
Boron Doping ◽  
Native Defects ◽  
Heavily Doped ◽  
Rich Material ◽  
P Type ◽  
Cubic Silicon Carbide

ABSTRACTWe report the results of a comprehensive theoretical investigation of the effects of stoichiometry and boron doping on the properties of cubic SiC. Supercell calculations using ab initio pseudopotentials show that the lowest energy defect in Si-rich n-type and intrinsic SiC is the electrically inactive Sic antisite, while VC++ is the lowest energy defect in p-type SiC. The electrons released by the carbon vacancies compensate acceptor dopants and lead to strong self-compensation effects when doping occurs during the growth of crystal. In C-rich SiC the dominant defect for all Fermi level positions is the electrically inactive CSi antisite. In stoichiometric and Si-rich cubic SiC, the BC site is energetically preferred, while BC and BSi have similar incorporation energies in C-rich material. In heavily doped p-type SiC the diffusion of BC proceeds by the dissociative (Frank-Turnbull) mechanism.

scholarly journals Investigation of Electronic Conductivity in PbI2:Hf Single Crystals

2019 ◽  
Vol 20 (4) ◽  
pp. 396-400
Author(s):  
T.V. Furs ◽  
O.I. Hulaj ◽  
V.Ya. Shemet
Keyword(s):  
Activation Energy ◽  
Single Crystal ◽  
Single Crystals ◽  
Electronic Conductivity ◽  
Hole Conductivity ◽  
Electron Hole ◽  
Upper Limit ◽  
Increasing Temperature ◽  
P Type ◽  
Current Potential

A study of the electron-hole conductivity in PbI2 single crystals doped with Hf (0.2 wt %) was conducted using the Wagner polarization cell method. The influence of the Hf alloying admixture (0.2 mass%) on the nature and parameters of lead diiodide’s electronic conductivity has been analyzed. Basing on the received current-potential dependences, p-type conductivity of a single crystal PbI2:Hf was established. The hole conductivity values (sро) were determined in the studied temperature range allowing to construct temperature dependence. The sро value for single crystal PbI2:Hf increased responsively to increasing temperature. For PbI2 and PbI2:Hf, a comparative analysis of the electron-hole conductivity was carried out. This investigation allowed determining the activation energy sро reduction from 0.47 eV to 0.32 eV due to hafnium doping. Consequently, the presence of Hf admixture in PbI2 crystals causes new impurity acceptor levels located at a distance of 0.64 eV from the upper limit of the valence zone.

Fermi Level Effects on Dislocation Formation in InAs1−xSbx Grown by MOCVD

1991 ◽  
Vol 240 ◽  
Author(s):  
R. M. Biefeld ◽  
T. J. Drummond
Keyword(s):  
Fermi Level ◽  
Carrier Concentration ◽  
Chemical Vapor ◽  
Layer Growth ◽  
Buffer Layers ◽  
Organic Chemical ◽  
Intrinsic Carrier Concentration ◽  
Strained Layer Superlattice ◽  
P Type ◽  
Dislocation Formation

ABSTRACTDislocation formation in InAs1−xSbx buffer layers grown on InSb substrates by metal-organic chemical vapor deposition is shown to be reproducibly enhanced by p-type doping at levels exceeding the intrinsic carrier concentration at the growth temperature. To achieve a carrier concentration greater than 2 × 1018 cm−3, the intrinsic carrier concentration of InSb at 475 C, p-type doping with diethylzinc was used. Carrier concentrations up to 6 × 1018 cm−3 were obtained. The zinc doped buffer layers have proven to be reproducibly crack free for InAs1−xSbx step graded buffer layers with a final composition of x = 0.12 lattice matched to a strained layer superlattice (SLS) with an average composition of x = 0.09. These structures have been used to prepare infrared photodiodes. Details of the buffer layer growth, an explanation for the observed Fermi level effect and the growth and characterization of an infrared photodiode are discussed.

High-performance n- and p-type organic single-crystal field-effect transistors with an air-gap dielectric towards anti-ambipolar transport

2020 ◽  
Vol 8 (13) ◽  
pp. 4303-4308 ◽  
Author(s):  
Jianghong Liu ◽  
Jie Liu ◽  
Jing Zhang ◽  
Chunlei Li ◽  
Qiuhong Cui ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Field Effect ◽  
High Performance ◽  
Field Effect Transistors ◽  
Air Gap ◽  
Crystal Field Effect ◽  
Organic Single Crystal ◽  
P Type ◽  
Ambipolar Transport

By combining high-performance n- and p-type single crystals with an air-gap dielectric, excellent anti-ambipolar transport with a small hysteresis was achieved.

scholarly journals The Singularity Paramagnetic Peak of Bi0.3Sb1.7Te3 with p-type Surface State

2022 ◽  
Vol 17 (1) ◽  
Author(s):  
Shiu-Ming Huang ◽  
Pin-Cing Wang ◽  
Pin-Cyuan Chen ◽  
Jai-Long Hong ◽  
Cheng-Maw Cheng ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Fermi Level ◽  
Single Crystal ◽  
Temperature Variation ◽  
Surface State ◽  
Dirac Point ◽  
Magnetization Measurement ◽  
Spin Texture ◽  
P Type ◽  
Susceptibility Curve

AbstractThe magnetization measurement was performed in the Bi0.3Sb1.7Te3 single crystal. The magnetic susceptibility revealed a paramagnetic peak independent of the experimental temperature variation. It is speculated to be originated from the free-aligned spin texture at the Dirac point. The ARPES reveals that the Fermi level lies below the Dirac point. The Fermi wavevector extracted from the de Haas–van Alphen oscillation is consistent with the energy dispersion in the ARPES. Our experimental results support that the observed paramagnetic peak in the susceptibility curve does not originate from the free-aligned spin texture at the Dirac point.

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