scholarly journals Band engineering of Dirac cones in iron chalcogenides

2020 ◽  
Vol 102 (5) ◽  
Author(s):  
Lars Lauke ◽  
Rolf Heid ◽  
Michael Merz ◽  
Thomas Wolf ◽  
Amir-Abbas Haghighirad ◽  
...  
Keyword(s):  
Band Engineering ◽  
Iron Chalcogenides

Band engineering in nitrogen-rich AlGaNAs quaternary alloys

Vacuum ◽  
2021 ◽  
pp. 110240
Author(s):  
M. Grodzicki ◽  
D. Majchrzak ◽  
E. Zdanowicz ◽  
C. Benjamin ◽  
P. Ciechanowicz ◽  
...  
Keyword(s):  
Quaternary Alloys ◽  
Band Engineering

scholarly journals Strain Effects on the Electronic and Thermoelectric Properties of n(PbTe)-m(Bi2Te3) System Compounds

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4086
Author(s):  
Weiliang Ma ◽  
Marie-Christine Record ◽  
Jing Tian ◽  
Pascal Boulet
Keyword(s):  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Compressive Strain ◽  
Van Der Waals Interactions ◽  
Functional Theory ◽  
Band Engineering ◽  
Seebeck Coefficients ◽  
The Density Functional Theory ◽  
P Type ◽  
Narrow Band Gap Semiconductors

Owing to their low lattice thermal conductivity, many compounds of the n(PbTe)-m(Bi2Te3) homologous series have been reported in the literature with thermoelectric (TE) properties that still need improvement. For this purpose, in this work, we have implemented the band engineering approach by applying biaxial tensile and compressive strains using the density functional theory (DFT) on various compounds of this series, namely Bi2Te3, PbBi2Te4, PbBi4Te7 and Pb2Bi2Te5. All the fully relaxed Bi2Te3, PbBi2Te4, PbBi4Te7 and Pb2Bi2Te5 compounds are narrow band-gap semiconductors. When applying strains, a semiconductor-to-metal transition occurs for all the compounds. Within the range of open-gap, the electrical conductivity decreases as the compressive strain increases. We also found that compressive strains cause larger Seebeck coefficients than tensile ones, with the maximum Seebeck coefficient being located at −2%, −6%, −3% and 0% strain for p-type Bi2Te3, PbBi2Te4, PbBi4Te7 and Pb2Bi2Te5, respectively. The use of the quantum theory of atoms in molecules (QTAIM) as a complementary tool has shown that the van der Waals interactions located between the structure slabs evolve with strains as well as the topological properties of Bi2Te3 and PbBi2Te4. This study shows that the TE performance of the n(PbTe)-m(Bi2Te3) compounds is modified under strains.

Boosting the thermoelectric performance of Fe2VAl−type Heusler compounds by band engineering

2021 ◽  
Vol 103 (8) ◽  
Author(s):  
F. Garmroudi ◽  
A. Riss ◽  
M. Parzer ◽  
N. Reumann ◽  
H. Müller ◽  
...  
Keyword(s):  
Thermoelectric Performance ◽  
Heusler Compounds ◽  
Band Engineering

scholarly journals Band Engineering and Morphology Control of Oxygen-Incorporated Graphitic Carbon Nitride Porous Nanosheets for Highly Efficient Photocatalytic Hydrogen Evolution

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Yunyan Wu ◽  
Pan Xiong ◽  
Jianchun Wu ◽  
Zengliang Huang ◽  
Jingwen Sun ◽  
...  
Keyword(s):  
Surface Area ◽  
Hydrogen Evolution ◽  
Carbon Nitride ◽  
Separation Efficiency ◽  
Physical Adsorption ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Photocatalytic Hydrogen Evolution ◽  
Band Engineering ◽  
Highly Efficient

AbstractGraphitic carbon nitride (g-C3N4)-based photocatalysts have shown great potential in the splitting of water. However, the intrinsic drawbacks of g-C3N4, such as low surface area, poor diffusion, and charge separation efficiency, remain as the bottleneck to achieve highly efficient hydrogen evolution. Here, a hollow oxygen-incorporated g-C3N4 nanosheet (OCN) with an improved surface area of 148.5 m2 g−1 is fabricated by the multiple thermal treatments under the N2/O2 atmosphere, wherein the C–O bonds are formed through two ways of physical adsorption and doping. The physical characterization and theoretical calculation indicate that the O-adsorption can promote the generation of defects, leading to the formation of hollow morphology, while the O-doping results in reduced band gap of g-C3N4. The optimized OCN shows an excellent photocatalytic hydrogen evolution activity of 3519.6 μmol g−1 h−1 for ~ 20 h, which is over four times higher than that of g-C3N4 (850.1 μmol g−1 h−1) and outperforms most of the reported g-C3N4 catalysts.

scholarly journals Temperature Dependence of Carrier Extraction Processes in GaSb/AlGaAs Quantum Nanostructure Intermediate-Band Solar Cells

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 344
Author(s):  
Yasushi Shoji ◽  
Ryo Tamaki ◽  
Yoshitaka Okada
Keyword(s):  
Solar Cells ◽  
Molecular Beam ◽  
Optical Excitation ◽  
Material System ◽  
Intermediate Band ◽  
Temperature Characteristics ◽  
Quantum Nanostructures ◽  
Band Engineering ◽  
Intermediate Band Solar Cells ◽  
Carrier Extraction

From the viewpoint of band engineering, the use of GaSb quantum nanostructures is expected to lead to highly efficient intermediate-band solar cells (IBSCs). In IBSCs, current generation via two-step optical excitations through the intermediate band is the key to the operating principle. This mechanism requires the formation of a strong quantum confinement structure. Therefore, we focused on the material system with GaSb quantum nanostructures embedded in AlGaAs layers. However, studies involving crystal growth of GaSb quantum nanostructures on AlGaAs layers have rarely been reported. In our work, we fabricated GaSb quantum dots (QDs) and quantum rings (QRs) on AlGaAs layers via molecular-beam epitaxy. Using the Stranski–Krastanov growth mode, we demonstrated that lens-shaped GaSb QDs can be fabricated on AlGaAs layers. In addition, atomic force microscopy measurements revealed that GaSb QDs could be changed to QRs under irradiation with an As molecular beam even when they were deposited onto AlGaAs layers. We also investigated the suitability of GaSb/AlGaAs QDSCs and QRSCs for use in IBSCs by evaluating the temperature characteristics of their external quantum efficiency. For the GaSb/AlGaAs material system, the QDSC was found to have slightly better two-step optical excitation temperature characteristics than the QRSC.

Rational band engineering and structural manipulations inducing high thermoelectric performance in n-type CoSb3 thin films

Nano Energy ◽  
2021 ◽  
Vol 81 ◽  
pp. 105683
Author(s):  
Zhuang-Hao Zheng ◽  
Xiao-Lei Shi ◽  
Dong-Wei Ao ◽  
Wei-Di Liu ◽  
Yue-Xing Chen ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermoelectric Performance ◽  
Band Engineering

Photonic Band Engineering of Coupled Waveguide Using Geometrical Modulation

2008 ◽  
Vol 47 (12) ◽  
pp. 8829-8833 ◽  
Author(s):  
Jun-ichiro Sugisaka ◽  
Noritsugu Yamamoto ◽  
Seok-Hwan Jeong ◽  
Kazuhiro Komori ◽  
Masahide Itoh ◽  
...  
Keyword(s):  
Band Engineering ◽  
Photonic Band
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