Possibility of Self-Trapped Excitons in Silicon Nanocrystallites

1995 ◽  
Vol 405 ◽  
Author(s):  
G. Allan ◽  
C. Delerue ◽  
M. Lannoo
Keyword(s):  
Quantum Confinement ◽  
Silicon Oxide ◽  
Light Emission ◽  
Local Density ◽  
Tight Binding ◽  
Localized States ◽  
Hydrogen Atoms ◽  
Quantum Confinement Effects ◽  
Silicon Nanocrystallites ◽  
Semi Empirical

AbstractWe present semi-empirical tight-binding and ab-initio local density calculations demonstrating the (meta)stability of self-trapped excitons in silicon nanocrystallites. These are obtained not only for surface dimer bonds passivated for instance by hydrogen atoms or by silicon oxide but also for “normal” nearest-neighbors bonds. Light emission from these trapped excitons is predicted in the infrared or in the visible. We are thus led to the interpretation that part of the luminescence is due to such localized states while optical absorption is characteristic of quantum confinement effects. These conclusions should extend to other semiconductor crystallites.

Theory of Pressure Effects on Silicon Nanocrystallites

1996 ◽  
Vol 452 ◽  
Author(s):  
G. Allan ◽  
C. Delerue ◽  
M. Lannoo
Keyword(s):  
Quantum Confinement ◽  
Radiative Recombination ◽  
Local Density ◽  
Tight Binding ◽  
Pressure Effects ◽  
Radiative Recombination Rate ◽  
Electron Hole ◽  
Silicon Nanocrystallites ◽  
Semi Empirical ◽  
Confinement Model

AbstractPressure effects on silicon nanocrystallites are calculated using semi-empirical tight-binding and ab-initio local density calculations. Using the confinement model in porous silicon a red shift of the luminescence energy with increasing pressure is obtained. Quantum confinement in BC8 phase silicon nanocrystallites obtained after release of high pressure are also studied. It increases the cluster gap and also enhances the electron-hole radiative recombination rate.

Observation of Quantum Confinement Effects in Nanocrystalline Silicon Dot Floating Gate Single Electron Memory Devices

2002 ◽  
Vol 737 ◽  
Author(s):  
Shaoyun Huang ◽  
Souri Banerjee ◽  
Shunri Oda
Keyword(s):  
Coulomb Blockade ◽  
Quantum Confinement ◽  
Silicon Oxide ◽  
Nanocrystalline Silicon ◽  
Floating Gate ◽  
Confinement Effects ◽  
Peak Structure ◽  
Quantum Confinement Effects ◽  
Charging And Discharging Processes ◽  
Charging Energy

ABSTRACTElectron charging and discharging processes in floating gate MOS memory based on nanocrystalline silicon (nc-Si) dots were investigated at room temperature using capacitance-voltage (C-V) and conductance-voltage (G-V) measurements. Sequential electron discharging processes from nc-Si dots manifest themselves clearly in G-V spectroscopy after charging of the dots. According to the conductance peak structure resulting from the Coulomb blockade as well as quantum confinement effects of nc-Si dots, electron-addition energy is estimated to be 50 meV. Taking the electron-charging energy between the silicon substrate and the floating dot (30 meV) into account, the quantum confinement energy is found to be comparable to the electron charging energy for an nc-Si dot of 8 nm in diameter embedded in the silicon oxide.

Photoluminescence quenching of inorganic cesium lead halides perovskite quantum dots (CsPbX3) by electron/hole acceptor

2017 ◽  
Vol 19 (3) ◽  
pp. 1920-1926 ◽  
Author(s):  
Yan-Xia Zhang ◽  
Hai-Yu Wang ◽  
Zhen-Yu Zhang ◽  
Yu Zhang ◽  
Chun Sun ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Confinement ◽  
Light Emission ◽  
Confinement Effects ◽  
Recombination Rates ◽  
Photoluminescence Quenching ◽  
Electron Hole ◽  
Carrier Recombination ◽  
Quantum Confinement Effects ◽  
Perovskite Quantum Dots

CsPbBr3 QDs with smaller size showed faster carrier recombination rates and PL decay lifetimes due to their relatively stronger quantum confinement effects, which may be useful for applications in photovoltaic and light emission devices.

A Simple Route to Growth of Silicon Nanowires

2008 ◽  
Vol 8 (11) ◽  
pp. 5787-5790
Author(s):  
Hui Pan ◽  
Zhenhua Ni ◽  
Cheekok Poh ◽  
Yuan Ping Feng ◽  
Jianyi Lin ◽  
...  
Keyword(s):  
Silicon Nanowires ◽  
Quantum Confinement ◽  
Silicon Oxide ◽  
Light Emission ◽  
Quantum Confinement Effect ◽  
Thermal Heating ◽  
Blue Light Emission ◽  
Silicon Oxides ◽  
Oxide Impurity ◽  
Amorphous Si

Silicon nanowires (SiNWs) have been produced by a simple thermal heating method with gold as a catalyst. The grown silicon nanowires were highly crystalline with little impurities such as amorphous Si and silicon oxides. Photoluminescence (PL) study has indicated that the Si band gap increases from 1.1 eV of bulk Si to 1.59 eV for the as-grown SiNWs due to quantum confinement effect. A strong PL peak around 540 nm (2.28 eV) is attributed to the relaxation of photon-induced self-trapped state in the form of surface Si–Si dimmers, while the blue light emission around 390 nm is attributed to the silicon oxide impurity on the SiNWs surface.

Effects of Structural Disorder on the Electronic Properties of Silicon: Tight-Binding Calculations of Grain Boundaries

1993 ◽  
Vol 297 ◽  
Author(s):  
M. Kohyama ◽  
R. Yamamoto
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Local Density ◽  
Tight Binding ◽  
Structural Disorder ◽  
Local Density Of States ◽  
Deep State ◽  
Amorphous Si ◽  
Semi Empirical ◽  
Twist Boundaries

The atomic and electronic structures of tilt and twist boundaries in Si have been calculated by using the transferable semi-empirical tight-binding (SETB) method, and the relations between the local structural disorder and the electronic properties of Si have been obtained clearly. The odd-membered rings and the four-membered rings induce the changes of the shape of the local density of states (LDOS). The bond distortions generate the peaks at the band edges in the LDOS, and greatly distorted bonds induce the weak-bond states inside the band gap. The three-coordinated defect generates a deep state in the band gap, which is much localized at the three-coordinated atom. The five-coordinated defect generates both deep and shallow states. The deep state is localized in the neighboring atoms except the five-coordinated atom, although the shallow states exist among the five-coordinated atom and the neighboring atoms. Configurations of boundaries are very effective in order to clarify the effects of the local structural disorder in amorphous SI.

GaAs Total Energy Tight Binding Hamiltonians for use in Molecular Dynamics

1990 ◽  
Vol 193 ◽  
Author(s):  
Jeremy Broughton ◽  
Mark Pederson ◽  
Dimitrios Papaconstantopoulos ◽  
David Singh
Keyword(s):  
Density Functional ◽  
Local Density ◽  
Tight Binding ◽  
Large Data ◽  
Matrix Elements ◽  
Energy Matrix ◽  
Self Consistent ◽  
Total Energies ◽  
Local Density Functional ◽  
Semi Empirical

ABSTRACTA self-consistent non-orthogonal semi-empirical tight binding Hamiltonian is proposed for GaAs, or any sp system, which is simple, reliable, transferable, accurate and fast to evaluate. Matrix elements are functions of charges, distances between atoms and simple cosines of angles between s and p-electron densities and interatomic vectors which maintain the simplicity of Slater-Koster parameterizations. The tight binding scheme is fit against a large data base of local density functional derived total energies for systems of differing coordination and geometry. The Hamiltonian fulfills the correct Virial constraint, invokes the physically correct relationship between overlap and kinetic energy matrix elements and defines charges via Mulliken or Löwdin schemes. Such Hamiltonians will allow the reliable simulation of statistical mechanically interesting systems of order hundred or more atoms over physically useful periods of time of order tens to hundreds of thousands of time steps within not unreasonable supercomputer budgets.

scholarly journals ELECTRONIC STATES AND LOCAL DENSITY OF STATES NEAR GRAPHENE CORNER EDGE

2012 ◽  
Vol 11 ◽  
pp. 151-156 ◽  
Author(s):  
YUJI SHIMOMURA ◽  
YOSITAKE TAKANE ◽  
KATSUNORI WAKABAYASHI
Keyword(s):  
Density Of States ◽  
Nearest Neighbor ◽  
Local Density ◽  
Tight Binding ◽  
Localized States ◽  
Destructive Interference ◽  
Edge States ◽  
Local Density Of States ◽  
Binding Model ◽  
Recursion Method

We study that stability of edge localized states in semi-infinite graphene with a corner edge of the angles 60°, 90°, 120° and 150°. We adopt a nearest-neighbor tight-binding model to calculate the local density of states (LDOS) near each corner edge using Haydock's recursion method. The results of the LDOS indicate that the edge localized states stably exist near the 60°, 90°, and 150° corner, but locally disappear near the 120° corner. By constructing wave functions for a graphene ribbon with three 120° corners, we show that the local disappearance of the LDOS is caused by destructive interference of edge states and evanescent waves.

A Novel Way to Prepare Silicon Oxide Nanomaterials with White Light Emission by Reactive Ladder Polyhydrosilsesquioxane

2012 ◽  
Vol 1 (1) ◽  
pp. 76-80
Author(s):  
Zhongjie Ren ◽  
Rongben Zhang ◽  
Fengwen Yan ◽  
Shidong Jiang ◽  
Feng Wang ◽  
...  
Keyword(s):  
White Light ◽  
Silicon Oxide ◽  
Light Emission ◽  
White Light Emission
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