scholarly journals E-kRelation of Valence Band in Arbitrary Orientation/Typical Plane Uniaxially Strained

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Zhang Chao ◽  
Xu Da-Qing ◽  
Liu Shu-Lin ◽  
Liu Ning-Zhuang
Keyword(s):  
Valence Band ◽  
Theoretical Basis ◽  
Carrier Mobility ◽  
Energy Levels ◽  
Hole Mobility ◽  
Strained Si ◽  
Effective Masses ◽  
Splitting Energy ◽  
Analytic Models ◽  
Strained Materials

Uniaxial strain technology is an effective way to improve the performance of the small size CMOS devices, by which carrier mobility can be enhanced. TheE-krelation of the valence band in uniaxially strained Si is the theoretical basis for understanding and enhancing hole mobility. The solving procedure of the relation and its analytic expression were still lacking, and the compressive results of the valence band parameters in uniaxially strained Si were not found in the references. So, theE-krelation has been derived by taking strained Hamiltonian perturbation into account. And then the valence band parameters were obtained, including the energy levels at Γ point, the splitting energy, and hole effective masses. Our analytic models and quantized results will provide significant theoretical references for the understanding of the strained materials physics and its design.

Model of DOS near the Top of Valence Band in Strained Si1-xGex/(001)Si

2011 ◽  
Vol 55-57 ◽  
pp. 979-982
Author(s):  
Jian Jun Song ◽  
Heng Sheng Shan ◽  
He Ming Zhang ◽  
Hui Yong Hu ◽  
Guan Yu Wang ◽  
...  
Keyword(s):  
Effective Mass ◽  
Valence Band ◽  
Theoretical Basis ◽  
Hole Mobility ◽  
Physical Parameters ◽  
Density Of State ◽  
Strained Si ◽  
Hole Effective Mass ◽  
Effective Masses ◽  
Material Physics

Strained Si1-xGextechnology has been widely adopted to enhance hole mobility. One of the most important physical parameters is density of state near the top of valence band in strained Si1-xGexmaterials. In this paper, we first obtained the hole effective mass along arbitrarily k wavevector directions, the hole isotropic effective masses and density of state effective mass of hole in strained Si1-xGex/(001)Si with the framework of K.P theory. And then, model of density of state near the top of valence band in strained Si1-xGex/(001)Si materials was established, which can provide valuable references to the understanding on its material physics and theoretical basis on the other important physical parameters.

Time-resolved Photoconductivity as a Probe of Carrier Transport in Microcrystalline Silicon

2006 ◽  
Vol 910 ◽  
Author(s):  
Steve Reynolds
Keyword(s):  
Density Of States ◽  
Carrier Mobility ◽  
Carrier Transport ◽  
Film Growth ◽  
Hole Mobility ◽  
Transport Parameters ◽  
Microcrystalline Silicon ◽  
Time Resolved ◽  
Transient Photoconductivity ◽  
Transport Measurements

AbstractThe use of transient photoconductivity techniques in the investigation of carrier transport in microcrystalline silicon is described. Results are presented which highlight variations in transport parameters such as carrier mobility and density of states with structure composition. Hole mobility is significantly enhanced by crystalline content in the film of 10% or less. The density of states inferred from transport measurements parallel to and at right angles to the direction of film growth differ somewhat, suggesting that transport may be anisotropic.

Direct evaluation of hole effective mass of SnS–SnSe solid solutions with ARPES measurement

2021 ◽  
Author(s):  
Issei Suzuki ◽  
Zexin Lin ◽  
Sakiko Kawanishi ◽  
Kiyohisa Tanaka ◽  
Yoshitaro Nose ◽  
...  
Keyword(s):  
Effective Mass ◽  
Valence Band ◽  
Thermoelectric Properties ◽  
Solid Solutions ◽  
Photoemission Spectroscopy ◽  
Direct Evaluation ◽  
Hole Effective Mass ◽  
Single Crystalline ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Effective Masses

Valence band dispersions of single-crystalline SnS1-xSex solid solutions were observed by angle-resolved photoemission spectroscopy (ARPES). The hole effective masses, crucial factors in determining thermoelectric properties, were directly evaluated. They decrease...

Solid-phase crystallization of ultra-thin amorphous Ge layers on insulators

2021 ◽  
Author(s):  
Ryo Oishi ◽  
Koji ASAKA ◽  
Bolotov Leonid ◽  
Noriyuki Uchida ◽  
Masashi Kurosawa ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Barrier Height ◽  
Carrier Mobility ◽  
Solid Phase ◽  
Hole Mobility ◽  
Solid Phase Crystallization ◽  
Simple Method ◽  
20 Nm ◽  
Grain Boundary Barrier

Abstract A simple method to form ultra-thin (< 20 nm) semiconductor layers with a higher mobility on a 3D-structured insulating surface is required for next-generation nanoelectronics. We have investigated the solid-phase crystallization of amorphous Ge layers with thicknesses of 10−80 nm on insulators of SiO2 and Si3N4. We found that decreasing the Ge thickness reduces the grain size and increases the grain boundary barrier height, causing the carrier mobility degradation. We examined two methods, known effective to enhance the grain size in the thicker Ge (>100 nm). As a result, a relatively high Hall hole mobility (59 cm2/Vs) has been achieved with a 20-nm-thick polycrystalline Ge layer on Si3N4, which is the highest value among the previously reported works.

Hole Mobility Enhancement Observed in (110)-Oriented Strained Si

2019 ◽  
Author(s):  
K. Arimoto ◽  
N. Utsuyama ◽  
S. Mitsui ◽  
K. Satoh ◽  
T. Yamada ◽  
...  
Keyword(s):  
Hole Mobility ◽  
Strained Si

scholarly journals Progress on the Synthesis and Application of CuSCN Inorganic Hole Transport Material in Perovskite Solar Cells

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2592 ◽  
Author(s):  
Funeka Matebese ◽  
Raymond Taziwa ◽  
Dorcas Mutukwa
Keyword(s):  
Solar Cells ◽  
Energy Levels ◽  
Perovskite Solar Cells ◽  
Hole Mobility ◽  
Cost Effective ◽  
Vital Role ◽  
Hole Transport ◽  
Recombination Processes ◽  
Short Synthesis ◽  
P Type

P-type wide bandgap semiconductor materials such as CuI, NiO, Cu2O and CuSCN are currently undergoing intense research as viable alternative hole transport materials (HTMs) to the spiro-OMeTAD in perovskite solar cells (PSCs). Despite 23.3% efficiency of PSCs, there are still a number of issues in addition to the toxicology of Pb such as instability and high-cost of the current HTM that needs to be urgently addressed. To that end, copper thiocyanate (CuSCN) HTMs in addition to robustness have high stability, high hole mobility, and suitable energy levels as compared to spiro-OMeTAD HTM. CuSCN HTM layer use affordable materials, require short synthesis routes, require simple synthetic techniques such as spin-coating and doctor-blading, thus offer a viable way of developing cost-effective PSCs. HTMs play a vital role in PSCs as they can enhance the performance of a device by reducing charge recombination processes. In this review paper, we report on the current progress of CuSCN HTMs that have been reported to date in PSCs. CuSCN HTMs have shown enhanced stability when exposed to weather elements as the solar devices retained their initial efficiency by a greater percentage. The efficiency reported to date is greater than 20% and has a potential of increasing, as well as maintaining thermal stability.

scholarly journals Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications

2017 ◽  
Vol 13 ◽  
pp. 863-873 ◽  
Author(s):  
Vinila N Viswanathan ◽  
Arun D Rao ◽  
Upendra K Pandey ◽  
Arul Varman Kesavan ◽  
Praveen C Ramamurthy
Keyword(s):  
Molecular Orbital ◽  
Architectural Design ◽  
Density Functional ◽  
Short Circuit ◽  
Energy Levels ◽  
Photovoltaic Performance ◽  
Hole Mobility ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Lowest Unoccupied Molecular Orbital

A series of low band gap, planar conjugated polymers, P1 (PFDTBT), P2 (PFDTDFBT) and P3 (PFDTTBT), based on fluorene and benzothiadiazole, was synthesized. The effect of fluorine substitution and fused aromatic spacers on the optoelectronic and photovoltaic performance was studied. The polymer, derived from dithienylated benzothiodiazole and fluorene, P1, exhibited a highest occupied molecular orbital (HOMO) energy level at −5.48 eV. Density functional theory (DFT) studies as well as experimental measurements suggested that upon substitution of the acceptor with fluorine, both the HOMO and lowest unoccupied molecular orbital (LUMO) energy levels of the resulting polymer, P2, were lowered, leading to a higher open circuit voltage and short circuit current with an overall improvement of more than 110% for the photovoltaic devices. Moreover, a decrease in the torsion angle between the units was also observed for the fluorinated polymer P2 due to the enhanced electrostatic interaction between the fluorine substituents and sulfur atoms, leading to a high hole mobility. The use of a fused π-bridge in polymer P3 for the enhancement of the planarity as compared to the P1 backbone was also studied. This enhanced planarity led to the highest observed mobility among the reported three polymers as well as to an improvement in the device efficiency by more than 40% for P3.

scholarly journals Outstanding thermoelectric properties of solvothermal-synthesized Sn1−3xInxAg2xTe micro-crystals through defect engineering and band tuning

2020 ◽  
Vol 8 (7) ◽  
pp. 3978-3987 ◽  
Author(s):  
Raza Moshwan ◽  
Wei-Di Liu ◽  
Xiao-Lei Shi ◽  
Qiang Sun ◽  
Han Gao ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Transport Properties ◽  
Valence Band ◽  
Thermoelectric Properties ◽  
Electrical Transport ◽  
Energy Levels ◽  
Resonance Energy ◽  
Defect Engineering ◽  
Electrical Transport Properties ◽  
Co Doping

In eco-friendly SnTe thermoelectrics, In and Ag co-doping induces the synergistic effect of resonance energy levels and valence band convergence to enhance its electrical transport properties, while defects ameliorates its thermal transport.

scholarly journals Resistivity and Carrier Mobility of the SmBa2 Cu3 O6+x Superconductor with Different Oxygen Doping Levels

1999 ◽  
Vol 54 (2) ◽  
pp. 95-100 ◽  
Author(s):  
G. Spinolo ◽  
P. Ghigna ◽  
G. Chiodelli ◽  
M. Ferretti ◽  
G. Flor
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Oxygen Pressure ◽  
Anderson Localization ◽  
Carrier Mobility ◽  
Hole Mobility ◽  
Dc Conductivity ◽  
Sudden Increase ◽  
Conductivity Measurements ◽  
Oxygen Doping

Abstract DC conductivity measurements between 15 and 300 K are reported for SmBa2 Cu3O6+x samples with different oxygen doping amounts (x) produced by annealing under appropriate high temperature and oxygen pressure conditions and quenching. Samples with x≥0.5 are superconductors: Tc ~60 K at x=0.7, Tc >80 K at ; x=0.9. The transition from superconduction to non-superconduction corresponds to the tetragonal to orthorhombic structural tran-sition and to the transition from semiconducting to metallic temperature dependence of the resistivity. Oxygen doping causes a sudden increase of hole mobility near x=0.5. Below this threshold, the be-havior of the carrier mobility is in agreement with an Anderson localization.

Sign in / Sign up

Export Citation Format

Share Document