Proposal of quantum well gate insulating (QWGI) structures for band offset engineering from first-principles calculations

2003 ◽  
Author(s):  
T. Schimizu ◽  
T. Yamaguchi
Keyword(s):  
Quantum Well ◽  
First Principles ◽  
Band Offset ◽  
First Principles Calculations

scholarly journals Probing embedded topological modes in bulk-like GeTe-Sb2Te3 heterostructures

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hisao Nakamura ◽  
Johannes Hofmann ◽  
Nobuki Inoue ◽  
Sebastian Koelling ◽  
Paul M. Koenraad ◽  
...  
Keyword(s):  
Topological Insulator ◽  
First Principles ◽  
Atom Probe ◽  
Photoemission Spectroscopy ◽  
Band Offset ◽  
First Principles Calculations ◽  
Vacuum Interface ◽  
Topological States ◽  
Experimental Findings ◽  
Thick Layers

AbstractThe interface between topological and normal insulators hosts metallic states that appear due to the change in band topology. While topological states at a surface, i.e., a topological insulator-air/vacuum interface, have been studied intensely, topological states at a solid-solid interface have been less explored. Here we combine experiment and theory to study such embedded topological states (ETSs) in heterostructures of GeTe (normal insulator) and $$\hbox {Sb}_2$$ Sb 2 $$\hbox {Te}_3$$ Te 3 (topological insulator). We analyse their dependence on the interface and their confinement characteristics. First, to characterise the heterostructures, we evaluate the GeTe-Sb$$_2$$ 2 Te$$_3$$ 3 band offset using X-ray photoemission spectroscopy, and chart the elemental composition using atom probe tomography. We then use first-principles to independently calculate the band offset and also parametrise the band structure within a four-band continuum model. Our analysis reveals, strikingly, that under realistic conditions, the interfacial topological modes are delocalised over many lattice spacings. In addition, the first-principles calculations indicate that the ETSs are relatively robust to disorder and this may have practical ramifications. Our study provides insights into how to manipulate topological modes in heterostructures and also provides a basis for recent experimental findings [Nguyen et al. Sci. Rep. 6, 27716 (2016)] where ETSs were seen to couple over thick layers.

Strain Effects on Optical Gain Properties of GaN/AlGaN Quantum Well Lasers

1996 ◽  
Vol 421 ◽  
Author(s):  
M. Suzuki ◽  
T. Uenoyama
Keyword(s):  
Quantum Well ◽  
First Principles ◽  
Carrier Density ◽  
Optical Gain ◽  
Uniaxial Strain ◽  
Quantum Well Lasers ◽  
Physical Parameters ◽  
First Principles Calculations ◽  
Strain Effects ◽  
Laser Performance

AbstractSubband structures and optical gains of the strained wurtzite GaN/AlGaN quantum well lasers are theoretically investigated on the basis of k.p theory. First-principles calculations are used for deriving the unknown physical parameters, such as deformation potentials. Neither compressive nor tensile biaxial strains are so effective on the reduction of the threshold carrier density. It is also found that the uniaxial strain in the c-plane is one of the preferable approaches for the efficient improvement of the laser performance.

scholarly journals First-principles calculations on CuInSe2/AlP heterostructures

2020 ◽  
Vol 8 (14) ◽  
pp. 4732-4742 ◽  
Author(s):  
Pingping Jiang ◽  
Marie-Christine Record ◽  
Pascal Boulet
Keyword(s):  
Conduction Band ◽  
Conversion Efficiency ◽  
First Principles ◽  
Band Offset ◽  
First Principles Calculations ◽  
Conduction Band Offset

Heterostructures based on a CuInSe2 absorber with an AlP buffer have a 12 meV conduction band offset and achieved 27.39% of conversion efficiency.

First principles calculations of the band offset at SrTiO3−TiO2 interfaces

2012 ◽  
Vol 101 (14) ◽  
pp. 141606 ◽  
Author(s):  
Nunzio Roberto D'Amico ◽  
Giovanni Cantele ◽  
Domenico Ninno
Keyword(s):  
First Principles ◽  
Band Offset ◽  
First Principles Calculations

scholarly journals Efficiency limits of Si/SiO2 quantum well solar cells from first-principles calculations

2009 ◽  
Vol 105 (10) ◽  
pp. 104511 ◽  
Author(s):  
Thomas Kirchartz ◽  
Kaori Seino ◽  
Jan-Martin Wagner ◽  
Uwe Rau ◽  
Friedhelm Bechstedt
Keyword(s):  
Solar Cells ◽  
Quantum Well ◽  
First Principles ◽  
First Principles Calculations
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