The optical transition in porous Si: The effects of quantum confinement, surface states and hydrogen passivation

1996 ◽  
Vol 18 (10) ◽  
pp. 1121-1129 ◽  
Author(s):  
Stefano Ossicini ◽  
O. Bisi
Keyword(s):  
Quantum Confinement ◽  
Optical Transition ◽  
Surface States ◽  
Hydrogen Passivation ◽  
Porous Si

scholarly journals Evidence for quantum confinement in the photoluminescence of porous Si and SiGe

1991 ◽  
Vol 59 (17) ◽  
pp. 2118-2120 ◽  
Author(s):  
S. Gardelis ◽  
J. S. Rimmer ◽  
P. Dawson ◽  
B. Hamilton ◽  
R. A. Kubiak ◽  
...  
Keyword(s):  
Quantum Confinement ◽  
Porous Si

Gas Sensor Using an Aluminium-Porous Silicon Junction Application to the Detection of Non-Zero Molecular Dipole Moment

1994 ◽  
Vol 358 ◽  
Author(s):  
D. Stievenard ◽  
D. Deresmes
Keyword(s):  
Dipole Moment ◽  
Porous Silicon ◽  
Silicon Oxide ◽  
Surface States ◽  
Dangling Bonds ◽  
Porous Si ◽  
Adsorbed Gas ◽  
Dipole Layer ◽  
Dc Current ◽  
Partial Depletion

ABSTRACTPorous silicon is known to be sensitive to moisture. Using an aluminium-porous p+ silicon junction, we have realized a sensor which dc current increases up to two orders of magnitude in the presence of ammoniac. We have tested a series of various gases and we show that if the dipole moment of the molecule is zero, there is no effect on the dc current. To interpret quantitatively this phenomenon, we assume that the conductivity is governed by the width of a channel resulting from the partial depletion of silicon located between two pores. This depleted region is due to the charges trapped on surface states associated with the Si-SiO2 interface where SiO2 is the native silicon oxide. When some gas is adsorbed, we propose there is a passivation of the interface states (mainly dangling bonds), leading to a decrease of the depleted region, i.e. an increase of the width of the channel and thus an increase of the current. The adsorbed gas gives a dipole layer at the surface of the pore. This layer has no influence on the depleted region. It stabilizes electrons or holes at the porous Si surface, allowing a stable charge state of the dangling bonds.

Picosecond Decay Dynamics in Porous Silicon

1992 ◽  
Vol 283 ◽  
Author(s):  
T. Matsumoto ◽  
T. Futagi ◽  
H. Mimura ◽  
Y. Kanemitsu
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Streak Camera ◽  
Luminescence Decay ◽  
Experimental Results ◽  
Porous Si ◽  
Emission Energy ◽  
Localized State ◽  
Hydrogen Termination

ABSTRACTPicosecond decay dynamics of luminescent porous silicon has been studied using the second harmonics (SH) of a cw modelocked YLF laser and a synchroscan streak camera. Picosecond luminescence decay shows nonexponential behavior that becomes large with decreasing emission energy. When increasing hydrogen termination on the surface of a Si microcrystal occurs, this picosecond luminescence decay becomes faster. Our experimental results indicate that there are two luminescent states in porous Si : a weak luminescent quantum confinement state and a strong luminescent surface localized state.

Silicon Nanostructures in Si-Based Light-Emithing Devices

1993 ◽  
Vol 298 ◽  
Author(s):  
Fereydoon Namavar ◽  
R.F. Pinizzotto ◽  
H. Yang ◽  
N. Kalkhoran ◽  
P. Maruska
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Silicon Nanostructures ◽  
Porous Si ◽  
Cross Sectional ◽  
Quantum Size ◽  
Visible Wavelengths ◽  
Si Nanostructures

AbstractHigh resolution cross-sectional electron microscopy and electron diffraction of an np heterojunction porous Si device, capable of emitting light at visible wavelengths, clearly indicates the presence of Si nanostructures within the quantum size regime. These results indicate that the quantum confinement effect is at least partially responsible for photoluminescence at visible wavelengths.

Virtual Synthesis and Optoelectronic Properties of Prismatic Artificial Molecules of In-N and Zn-O: Comparative Studies

2006 ◽  
Vol 959 ◽  
Author(s):  
Liudmila A Pozhar ◽  
Gail J Brown ◽  
William C Mitchel
Keyword(s):  
Electronic Properties ◽  
Quantum Confinement ◽  
Optical Transition ◽  
Level Structure ◽  
Open Shell ◽  
Complete Active Space ◽  
Synthesis Conditions ◽  
Hartree Fock ◽  
Self Consistent Field ◽  
Molecular Synthesis

ABSTRACTThe Hartree-Fock (HF), restricted open shell HF (ROHF), configuration interaction (CI), complete active space (ICASCF), and multiconfiguration self-consistent field (MCSCF) methods provide sophisticated fundamental theory-based, computational tools to study structure, composition,chemistry and electronic properties of small artificial molecules composed of semiconductor compound atoms. These tools are used to synthesize virtually several prismatic In-N and Zn-O artificial molecules whose structure is derived from that of the symmetry elements of the respective wurtzite bulk lattices. Applications of spatial constraints to the atomic coordinates allow modeling molecular synthesis in quantum confinement, to obtain pre-designed molecules with tunable electronic properties. Relaxation of these constraints, or optimization, leads to the corresponding molecules synthesized in “vacuum”. The development of computational templates of the studied artificial molecules synthesized in confinement reflects effects of quantum confinement on the electronic level structure, bonding, the direct optical transition energy, and charge and spin density distributions of the molecules. Comparison of the structure and properties of these molecules to those of their vacuum counterparts leads to a conclusion that a small changes in atomic positions in otherwise structurally similar molecules cause a significant change in their electronic properties. Thus, the electronic properties of artificial molecules can be tuned by changing their synthesis conditions that are defined by atomistic details of quantum confinement where the molecules are synthesized.

Quantum-confinement-induced periodic surface states in two-dimensional metal-organic frameworks

2020 ◽  
Vol 117 (19) ◽  
pp. 191601
Author(s):  
Chun-Sheng Zhou ◽  
Xiang-Rui Liu ◽  
Yue Feng ◽  
Xiji Shao ◽  
Meng Zeng ◽  
...  
Keyword(s):  
Quantum Confinement ◽  
Metal Organic Frameworks ◽  
Surface States ◽  
Two Dimensional ◽  
Periodic Surface ◽  
Metal Organic

Light Emission Induced by the Indium Distribution in InGaN Nanowires

2013 ◽  
Vol 815 ◽  
pp. 148-153
Author(s):  
Jun Jie Shi ◽  
Tie Cheng Zhou ◽  
Hong Xia Zhong ◽  
Xin He Jiang ◽  
Pu Huang
Keyword(s):  
First Principles ◽  
Electronic Structures ◽  
Light Emission ◽  
Optical Transition ◽  
Laser Diodes ◽  
Optoelectronic Devices ◽  
Surface States ◽  
First Principles Calculations ◽  
Light Emitting ◽  
Interband Optical Transition

The InGaN nanowires (NWs) have attracted intense attention for their huge potential in applications such as light emitting diodes, laser diodes and solar cells. Although lots of work are focused on improving their optical performance, little is known about the influence of the In distribution and the surface states on the microscopic light emission mechanism. In order to give an atomic level understanding, we investigate the electronic structures of the wurtziteGa-rich InGaN NWs with different In distributions using first-principles calculations. We find that the In-atoms are apt to distribute on the surface of the NWs and the short surface In-N chains can be easily formed. For the unsaturated NWs, several new bands are induced by the surface states, which can be modified by the surface In microstructures. The randomly formed surface In-N chains can highly localize the electrons/holes at the band edges and dominate the interband optical transition. For the saturated NWs, the band edges are determined by the inner atoms. Our work is useful to improve the performance of the InGaN NW-based optoelectronic devices.

Optical properties of porous silicon

1992 ◽  
Vol 70 (10-11) ◽  
pp. 1184-1193 ◽  
Author(s):  
D. J. Lockwood ◽  
G. C. Aers ◽  
L. B. Allard ◽  
B. Bryskiewicz ◽  
S. Charbonneau ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Confinement ◽  
Chemical Dissolution ◽  
Optical Absorption Spectra ◽  
Porous Si ◽  
Transmission Electron ◽  
Amorphous Si ◽  
Si Nanostructures ◽  
Si Films

The optical and structural properties of porous Si films produced by electrochemical and chemical dissolution of Si have been studied by a variety of techniques. Raman scattering and transmission electron microscopy have shown the samples to contain crystalline Si wires and (or) spherites 3–8 nm in diameter and (or) amorphous Si. The optical absorption spectra and the wavelength, temperature, and lifetime dependence of the photoluminescence obtained from most of the samples are entirely consistent with the quantum confinement of excitons in Si nanostructures. Quite different photoluminescence was obtained from other samples composed only of amorphous Si, and this is attributed to the presence of silicon oxyhydride species.

Opto-Electronic Properties and Stability of Artificial Zinc Oxide Molecules

2006 ◽  
Vol 957 ◽  
Author(s):  
Liudmila A Pozhar ◽  
Gail J. Brown
Keyword(s):  
Zinc Oxide ◽  
Electronic Properties ◽  
Quantum Confinement ◽  
Electronic Materials ◽  
Optical Transition ◽  
Open Shell ◽  
Hartree Fock ◽  
Alumina Membranes ◽  
Self Consistent Field ◽  
Nanopore Arrays

ABSTRACTThe Hartree-Fock (HF), restricted open shell HF (ROHF), and multiconfiguration self-consistent field (CI/CASSCF/MCSCF) approximations are used to study computationally the electronic properties of zinc oxide artificial molecules whose structure and composition have been derived from those of the symmetry elements of the wurtzite bulk lattice of zinc oxide. Such molecules may provide realistic models for small ZnO quantum dots (QDs) synthesized in “vacuum” or quantum confinement (such as that of well-defined nanopore arrays of silica and alumina membranes) using variety of methods in particular, supercritical fluid deposition. The computational direct optical transition energy (OTE) of the confined molecule appears to be several times smaller than that of the corresponding vacuum cluster. The charge and spin density distributions of these molecules (CDDs and SDDs, respectively) differ significantly, revealing dramatic effects of quantum confinement on electronic properties of Zn-O clusters. The obtained results suggest that manipulations with the electronic properties of the confined clusters by sophisticated design of their quantum confinement may provide means for synthesis of Zn-O – based electronic materials that combine a wide, tunable band gap with large, tunable exciton binding energy.

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