Localisation of Carriers in Porous Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
I. Mihalcescu ◽  
J. C. Vial ◽  
R. Romestain
Keyword(s):  
Simple Model ◽  
Porous Silicon ◽  
Temperature Variation ◽  
Time Evolution ◽  
Decay Time ◽  
Additional Assumption ◽  
Shape Evolution ◽  
Photoluminescence Intensity ◽  
Photoluminescence Decay ◽  
Strong Localization

AbstractWe analyze the intensity and decay time evolution of the porous silicon luminescence upon anodic oxidation, aging, chemiral thinning and temperature variation. Strong analogies are pointed out for the photoluminescence intensity as well as for the photoluminescence decay shape evolution. They are interpreted by the variation of the extension of the carrier wavefunction induced by the modification of potential barrier efficiencies. No additional assumption such as hopping of carriers was necessary to explain the decay shapes well fitted by stretched exponential. On the contrary our observations and our simple model are in favor of a strong localization of carriers. Some experimental results are revisited within the frame of this model.

CALCULATION OF SURFACE AREAS FOR POROUS SILICON

1999 ◽  
Vol 13 (28) ◽  
pp. 1005-1009
Author(s):  
Q. R. HOU ◽  
N. CHI
Keyword(s):  
Atomic Force Microscopy ◽  
Simple Model ◽  
Porous Silicon ◽  
Surface Area ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Photoluminescence Intensity ◽  
Force Microscopy ◽  
Surface Areas ◽  
Atomic Force

Based on atomic force microscopy (AFM) images of porous silicon, a simple model has been proposed to calculate the surface areas of porous silicon. In this model, the porous silicon layer is assumed to be made of numerous identical cones with radius r and height h. The surface area changes due to the formation of porous silicon are found to be dependent on (h/r)2 and correlate with the growth of photoluminescence (PL) intensities. The rise and fall in photoluminescence intensity coincide with those of surface area changes qualitatively. This coincidence supports the hypothesis that the luminescence results from the presence of surface-localized or confined molecular emitters.

The photoluminescence decay time of self-assembled InAs quantum dots covered by InGaAs layers

2006 ◽  
Vol 17 (23) ◽  
pp. 5722-5725 ◽  
Author(s):  
G W Shu ◽  
C K Wang ◽  
J S Wang ◽  
J L Shen ◽  
R S Hsiao ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Decay Time ◽  
Inas Quantum Dots ◽  
Photoluminescence Decay ◽  
Self Assembled

Microsecond photoluminescence decay and oxidation of porous silicon

1997 ◽  
Vol 102 (11) ◽  
pp. 813-816 ◽  
Author(s):  
H.Z. Song ◽  
G.G. Qin ◽  
D.C. Yao ◽  
Z.J. Chen ◽  
X.M. Bao
Keyword(s):  
Porous Silicon ◽  
Photoluminescence Decay

scholarly journals Porous Silicon Structural Evolution from In-Situ Luminescence and Raman Measurements

1996 ◽  
Vol 431 ◽  
Author(s):  
D. R. Tallant ◽  
M. J. Kelly ◽  
T. R. Guilinger ◽  
R. L. Simpson
Keyword(s):  
Porous Silicon ◽  
Silicon Surface ◽  
Structural Evolution ◽  
Surface Oxidation ◽  
Ethanol Solution ◽  
Nonradiative Recombination ◽  
Photoluminescence Intensity ◽  
Exciton Migration ◽  
Photoluminescence Mechanism

AbstractWe performed in-situ photoluminescence and Raman measurements on an anodized silicon surface in the HF/ethanol solution used for anodization. The porous silicon thereby produced, while resident in HF/ethanol, does not immediately exhibit intense photoluminescence. Intense photoluminescence develops spontaneously in HF/ethanol after 18–24 hours or with replacement of the HF/ethanol with water. These results support a quantum confinement mechanism in which exciton migration to traps and nonradiative recombination dominates the de-excitation pathways until silicon nanocrystals are physically separated and energetically decoupled by hydrofluoric acid etching or surface oxidation. The porous silicon surface, as produced by anodization, shows large differences in photoluminescence intensity and peak wavelength over millimeter distances. Parallel Raman measurements implicate nanometer-size silicon particles in the photoluminescence mechanism.

Photoluminescence decay time studies of type‐II GaAs/AlAs quantum well structures

1989 ◽  
Vol 66 (11) ◽  
pp. 5639-5641 ◽  
Author(s):  
M. D. Sturge ◽  
Janet L. Mackay ◽  
Colette Maloney ◽  
J.K. Pribram
Keyword(s):  
Quantum Well ◽  
Decay Time ◽  
Type Ii ◽  
Quantum Well Structures ◽  
Photoluminescence Decay

Observation of increased photoluminescence decay time in strain‐induced quantum‐well dots

1993 ◽  
Vol 62 (12) ◽  
pp. 1376-1378 ◽  
Author(s):  
I‐Hsing Tan ◽  
Ying‐Lan Chang ◽  
Richard Mirin ◽  
Evelyn Hu ◽  
James Merz ◽  
...  
Keyword(s):  
Quantum Well ◽  
Decay Time ◽  
Photoluminescence Decay

Depositing Metals into Porous Silicon - the Impact on Luminescence

1994 ◽  
Vol 358 ◽  
Author(s):  
P. Steiner ◽  
F. Kozlowski ◽  
W. Lang
Keyword(s):  
Porous Silicon ◽  
Porous Layer ◽  
Electron Microprobe ◽  
Uv Light ◽  
Electrochemical Process ◽  
Photoluminescence Intensity ◽  
Spectral Position ◽  
Metal Atoms ◽  
Metal Treatment ◽  
The Impact

ABSTRACTIndium, tin, antimony and aluminum are deposited by an electrochemical process into the pores of n-type porous silicon which is anodized with ultraviolet light applied during formation. The presence of these metal atoms in the porous layer is checked by electron microprobe measurement. As reported previously, UV-light etched material shows red photoluminescence (630 nm) and blue electroluminescence (470 nm) without the metal treatment. After metal deposition the photoluminescence intensity decreases slightly (factor 0.5 - 0.8), whereas the spectral position remains constant. The electroluminescence efficiency is significantly enhanced by indium, aluminum and tin in the pores (factor 5 - 90). The tin and antimony treatment causes a red shift to 580 nm and 740 nm, respectively. The conductivity is slightly increased by all kinds of metals by a factor 2-5.

The effect of barotropic instability on the nonlinear evolution of a Rossby-wave critical layer

1989 ◽  
Vol 207 ◽  
pp. 231-266 ◽  
Author(s):  
Peter H. Haynes
Keyword(s):  
Simple Model ◽  
Numerical Model ◽  
Time Evolution ◽  
Rossby Wave ◽  
Nonlinear Evolution ◽  
Basic Flow ◽  
Critical Layer ◽  
Barotropic Instability ◽  
Long Wavelength ◽  
Subsequent Time

A study of the flow within the critical layer of a forced Rossby-wave is made, using a high-resolution numerical model. The possibility of growth of disturbances through barotropic instability and the extent to which these disturbances modify the subsequent time evolution is of particular interest. The flow is characterized by a parameter μ, equal to the cross-stream lengthscale divided by a downstream wavelength. In the long-wavelength case, μ [Lt ] 1, where there is a clear conceptual division between the instability and the basic flow, the results of the simulation confirm the importance of the growing and saturating disturbances in rearranging the vorticity within the critical layer. When the wavelength is not so long, the distinction between the instability and the straightforward time evolution of the basic flow is less clear. Nonetheless for μ < 0.25 the ultimate evolution is still sensitive to the details of the initial perturbations and in this sense the flow may be regarded as being unstable. The time-integrated absorptivity of the critical layer may be considerably increased by the effects of the instability, sometimes to three or four times that predicted by the Stewartson-Warn-Warn solution. The nature of the flow, at least during the period in which the dynamics are essentially inviscid, does not seem to change when higher harmonics to the forced wave are resonant. The behaviour seen in Béland's (1976) numerical model is re-examined in the light of these findings. A simple model of the redistribution of vorticity by the unstable disturbances is formulated, and its predictions are shown to agree well with the numerical simulations.

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