Unusual interlayer coupling in layered Cu-based ternary chalcogenides CuMCh2(M=Sb, Bi; Ch=S, Se)

Nanoscale ◽  
2021 ◽  
Author(s):  
Dan-Dong Wang ◽  
Xin-Gao Gong ◽  
Jihui Yang
Keyword(s):  
Electronic Properties ◽  
Conduction Band ◽  
Interlayer Coupling ◽  
Conduction Band Minimum ◽  
Common Mechanism ◽  
Layered Semiconductors ◽  
Band Maximum ◽  
Valance Band Maximum

Interlayer interactions play important roles in manipulating the electronic properties of layered semiconductors. One common mechanism is that the valance band maximum (VBM) and the conduction band minimum (CBM) in...

Structural and Electronic Structure of SnO2 by the First-Principle Study

2012 ◽  
Vol 725 ◽  
pp. 265-268 ◽  
Author(s):  
Minoru Oshima ◽  
Kenji Yoshino
Keyword(s):  
Electronic Structure ◽  
Electronic Properties ◽  
Valence Band ◽  
Conduction Band ◽  
Valence Band Maximum ◽  
First Principle ◽  
Band Maximum ◽  
First Principle Calculations ◽  
Calculation Results ◽  
Good Agreement

We performed first-principle calculations to investigate the effects of F, Cl and Sb impurities on the electronic properties of SnO2. We obtained, firstly, the electronic structure of SnO2, a valence band maximum of SnO2is an O 2p orbital and a conduction band minimum was an antibonding Sn 5s and O 2p orbitals dominantly. Secondly, those impurites doped SnO2was obtained the electronic structure. The F, Cl and Sb impurities as n-type dopants exhibited shallow donors. This calculation results were in good agreement with our prvious experiment that we obtained the low resistivity SnO2.

scholarly journals A first-principles study of anionic (S) and cationic (V/Nb) doped Sr2Ta2O7 for visible light photocatalysis

RSC Advances ◽  
2017 ◽  
Vol 7 (65) ◽  
pp. 40922-40928 ◽  
Author(s):  
Yuman Peng ◽  
Zuju Ma ◽  
Junjie Hu ◽  
Kechen Wu
Keyword(s):  
Visible Light ◽  
Valence Band ◽  
Conduction Band ◽  
First Principles ◽  
Valence Band Maximum ◽  
Conduction Band Minimum ◽  
Visible Light Photocatalysis ◽  
Band Maximum ◽  
Co Doping ◽  
First Principles Study

In order to utilize the visible light to catalyze water, UV-active Sr2Ta2O7 is engineered via co-doping of S and V/Nb to shift the valence band maximum upward and conduction band minimum downward by approximately 1 eV, respectively.

Conduction band minimum of CdTe

1964 ◽  
Vol 25 (4) ◽  
pp. 443-447 ◽  
Author(s):  
W.G. Spitzer ◽  
C.A. Mead
Keyword(s):  
Conduction Band ◽  
Conduction Band Minimum

scholarly journals Conduction Band Engineering of Half-Heusler Thermoelectrics Using Orbital Chemistry

2022 ◽  
Author(s):  
Shuping Guo ◽  
Shashwat Anand ◽  
Madison K. Brod ◽  
Yongsheng Zhang ◽  
G. Jeffrey Snyder
Keyword(s):  
Electronic Properties ◽  
Valence Band ◽  
Conduction Band ◽  
Thermoelectric Materials ◽  
Band Engineering

Semiconducting half-Heusler (HH, XYZ) phases are promising thermoelectric materials owing to their versatile electronic properties. Because the valence band of half-Heusler phases benefits from the valence band extrema at several...

scholarly journals Energy Level Engineering of Charge Selective Contact and Halide Perovskite by Modulating Band Offset: Mechanistic Insights

2020 ◽  
Author(s):  
Yassine Raoui ◽  
Hamid Ez-Zahraouy ◽  
Samrana Kazim ◽  
Shahzada Ahmad
Keyword(s):  
Solar Cells ◽  
Energy Level ◽  
Conduction Band ◽  
Perovskite Solar Cells ◽  
Hole Transport ◽  
Conduction Band Minimum ◽  
Transport Layer ◽  
Hole Transport Layer ◽  
Band Offset ◽  
Interfacial Recombination

<p>Mixed cation and anion based perovskites solar cells (FAPbI<sub>3</sub>)<sub>0.85</sub>(MAPbBr<sub>3</sub>)<sub>0.15</sub> gave enhanced stability under outdoor conditions, however, it yielded limited power conversion efficiency when SnO<sub>2</sub> and Spiro-OMeTAD were employed as electron and hole transport layer (ETL/HTL). The inevitable interfacial recombination of charge carriers at ETL/perovskite and perovskite/HTL interface diminished the efficiency in planar (n-i-p) perovskite solar cells. Employing computational approach for uni-dimensional device simulator, the effect of band offset on charge recombination at both interfaces were investigated. We noted that it acquired cliff structure when the conduction band minimum of the ETL is lower than that of the perovskite, and thus maximizes interfacial recombination. However, if the conduction band minimum of ETL is higher than perovskite, i.e. spike structure is formed, which improve the performance of solar cell up to an optimum value of conduction band offset allowing to reach performance of 25.21%, with an open circuit voltage (<i>V</i><sub>oc</sub>) of 1231 mV, a current density <i>J</i><sub>sc</sub> of 24.57 mA/cm<sup>2</sup> and a fill factor of 83.28%. Additionally, we found that beyond the optimum offset value, large spike structure could decrease the performance. With an optimized, energy level of Spiro-OMeTAD and the thickness of mixed-perovskite layer performance of 26.56 % can be attained. Our results demonstrate a detailed understanding about the energy level tuning between the charge selective layers and perovskite and furthermore how the improvement in PV performance can be achieved by adjusting the energy level offset.</p>

Conduction band minimum of CdTe

1964 ◽  
Vol 2 (2) ◽  
pp. 62
Author(s):  
W.G. Spitzer ◽  
C.A. Mead
Keyword(s):  
Conduction Band ◽  
Conduction Band Minimum

NEGATIVE DIFFERENTIAL VELOCITY IN ARTIFICIAL CRYSTALS PROBED BY HIGH MAGNETIC FIELDS

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2766-2768
Author(s):  
A. PATANÈ
Keyword(s):  
Electrical Conductivity ◽  
Electric Field ◽  
Electronic Properties ◽  
Effective Mass ◽  
Conduction Band ◽  
Impurity Level ◽  
Frequency Range ◽  
Electron Effective Mass ◽  
N Level ◽  
Relief Effect

Progress in the synthesis and engineering of semiconductor materials has led to improved device performances and functionalities. In particular, in the last decade, there has been considerable interest in the physics and applications of highly-mismatched alloys in which small and highly-electronegative isovalent N -atoms are incorporated onto the anion sublattice of a III-V compound semiconductor.1 The most studied material is the GaAs 1-x N x alloy. Our magnetotunnelling studies have shown that a small percentage of N (x < 1%) perturbs dramatically the electronic properties of the host GaAs crystal leading to a large increase of the electron effective mass and an unusual response of the energy-wavevector dispersions to hydrostatic pressure.2–6 These effects differ from the smoother variation of the energy band gap and electron effective mass with alloy composition observed in other semiconductor compounds, such as In y Ga 1-y As . The incorporation of N in GaAs gives rise to a qualitatively different type of alloy phenomenon: N -impurities and N -clusters tend to localize the extended Bloch states of GaAs at resonant energies in the conduction band (CB), thus fragmenting the energy-wavevector dispersion relations. The possibility of tailoring the electronic properties of III-V compounds by N -incorporation has stimulated proposals for innovative devices in optoelectronics and high frequency (terahertz, THz) electronics.7 However, to date, the implementation of dilute nitrides in these technologies presents several challenges, including a degradation of the electron mobility. Also, despite a rapidly expanding body of work on the electronic properties of GaAs 1-x N x, the range of N -concentrations over which this alloy behaves as a good conductor is not yet well established. Our magnetotransport experiments have revealed how the incorporation of N in GaAs affects the electrical conductivity. Our studies in n-type GaAs 1-x N x epilayers revealed a large increase of the resistivity, ρ, for x > 0.2%, which we have attributed to the emergence of defect states with deep (~ 0.3 eV) energy levels. Electron trapping onto these states was not observed at low x (x = 0.2%). In this ultra-dilute alloy regime and at low electric fields (F < 1 kV / cm ) the electrical conductivity retains the characteristic features of transport through extended states, albeit with relatively low mobility (µ ~ 0.1 m 2/ Vs at RT) due to scattering of electrons by N -atoms. We have focused our research on this ultra-dilute regime and exploited the admixing of the localized single N -impurity level with the extended conduction band states of GaAs to realize an unusual type of negative differential velocity (NDV) effect: at large F (> 1 kV / cm ), electrons gain sufficient energy to approach the energy of the resonant N -level, where they become spatially localized.7–10 [Formula: see text] This Resonant Electron Localization in Electric Field, to which we give the acronym RELIEF, leads to NDV and strongly non-linear current-voltage characteristics. We envisage that the RELIEF-effect could be observed in other III-N-V alloys, such as InP 1-x N x and InAs 1-x N x. In these compounds the nature of the resonant interaction between the N -level and the conduction band states of the host-crystal is still relatively unexplored. However, it is clear that the different energy positions of the N -level relative to the conduction band minimum of different materials could offer new degrees of freedom in the design of the electronic band structure and electron dynamics. The RELIEF-effect may open up prospects for future applications in fast electronics. We have shown that the maximum response frequency, fmax, of a RELIEF-diode can be tuned by the applied electric field in the THz frequency range.7 This is of potential technological significance for the development of detectors/sources in the 0.6-1 THz region, which is not currently attainable using conventional Transferred Electron Devices and Quantum Cascade Lasers. Our recent studies of GaAs 1-x N x have also shown a fast response of the current in the sub-THz frequency range.11 Experiments involving diodes optimized for THz-operation coupled with a quantitative theoretical model of the THz dynamics will be now needed to assess the use of GaAs 1-x N x and other III-N-V alloys in detectors/sources of THz radiation. Note from Publisher: This article contains the abstract only.

Sign in / Sign up

Export Citation Format

Share Document