Can Oxidation and Other Treatments Help Us Understand the Nature of Light-Emitting Porous Silicon?

1993 ◽  
Vol 298 ◽  
Author(s):  
P.M. Fauchet ◽  
E. Ettedgui ◽  
A. Raisanen ◽  
L.J. Brillson ◽  
F. Seiferth ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Room Temperature ◽  
Vacuum Annealing ◽  
Surface States ◽  
Careful Analysis ◽  
Experimental Results ◽  
Dangling Bonds ◽  
Light Emitting ◽  
Confinement Model

AbstractUsing a careful analysis of the properties of light-emitting porous silicon (LEpSi), we conclude that a version of the “smart” quantum confinement model which was first proposed by F. Koch et al [Mat. Res. Soc. Symp. Proc. 283, 197 (1993)] and allows for the existence of surface states and dangling bonds, is compatible with experimental results. Among the new results we present in support of this model, the most striking ones concern the strong infrared photoluminescence that dominates the room temperature cw spectrum after vacuum annealing above 600 K.

Optical Studies of Electroluminescent Structures from Porous Silicon

1992 ◽  
Vol 283 ◽  
Author(s):  
J. F. Harvey ◽  
R. A. Lux ◽  
D. C. Morton ◽  
G. F. McLane ◽  
R. Tsu
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Room Temperature ◽  
Light Emitting Diode ◽  
Spectral Peak ◽  
Electrical Excitation ◽  
Silicon Structure ◽  
Electrical Measurements ◽  
Optical Studies ◽  
Light Emitting

ABSTRACTTwo components of the electroluminescence (EL) from porous silicon light emitting diode (LED) devices have been observed. A slower component and a faster component have been identified. The slower component has a spectral peak shifted to the red from the corresponding photoluminescence (PL) spectrum. The faster component has a spectral peak well in the infrared (IR). Optical and electrical measurements of these two components are discussed. The temperature dependence of the two EL components are presented and contrasted. Our measurements demonstrate that the two EL components and the PL result from recombination in different parts of the porous silicon structure. As the temperature is reduced below room temperature the slower EL exhibits a decrease in intensity at relatively high temperatures, suggesting a freeze out of electrical carriers due to quantum confinement, resulting in a much reduced electrical excitation of the EL.

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.

SiOx luminescence from light‐emitting porous silicon: Support for the quantum confinement/luminescence center model

1996 ◽  
Vol 68 (12) ◽  
pp. 1663-1665 ◽  
Author(s):  
D. W. Cooke ◽  
B. L. Bennett ◽  
E. H. Farnum ◽  
W. L. Hults ◽  
K. E. Sickafus ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Luminescence Center ◽  
Light Emitting

Photoluminescence in Porous Silicon: Evidence for the Quantum Confinement Model

1991 ◽  
Vol 256 ◽  
Author(s):  
David L. Naylor ◽  
Sung B. Lee ◽  
John C. Pincenti ◽  
Brett E. Bouma
Keyword(s):  
Porous Silicon ◽  
Hydrofluoric Acid ◽  
Quantum Wire ◽  
Quantum Confinement ◽  
Electrochemical Etching ◽  
Photoluminescence Spectra ◽  
Peak Wavelength ◽  
Effects Of Temperature ◽  
Good Agreement ◽  
Confinement Model

ABSTRACTPhotoluminescence spectra have been measured in porous silicon following electrochemical etching in dilute hydrofluoric acid (HF). The effects of HF concentration during etching on the efficiency and peak wavelength of photoluminescence have been investigated. The effects of temperature between 25°C and 200°C on PL spectra have been recorded. Photoluminescence lifetimes as a function of wavelength have been studied following ultrashort UV photoexcitation. A number of lifetime components in the decay are observed the longest in good agreement over the wavelength range of 500 to 600 nm with a silicon quantum wire model. At longer wavelengths a departure from lifetimes of the wire model is observed and two hypotheses for the discrepancy are presented.

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.

Er-Implanted Porous Silicon: a Novel Material for Si-Based Infrared LEDs

1994 ◽  
Vol 358 ◽  
Author(s):  
Fereydoon Namavar ◽  
F. Lu ◽  
C.H. Perry ◽  
A. Cremins ◽  
N.M. Kalkhoran ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Wide Bandgap ◽  
Device Fabrication ◽  
Porous Si ◽  
High Concentration ◽  
Light Emitting ◽  
Novel Material ◽  
Bandgap Semiconductors ◽  
Ir Emission

ABSTRACTWe have demonstrated a strong, room-temperature, 1.54 μm emission from erbium-implanted at 190 keV into red-emitting porous silicon. Luminescence data showed that the intensity of infrared (IR) emission from Er implanted porous Si annealed at ≤ 650°C, was a few orders of magnitude stronger than Er implanted quartz produced under identical conditions, and was almost comparable to IR emission from In0.53Ga0.47As material which is used for commercial IR light-emitting diodes (LEDs).The strong IR emission (much higher than Er in quartz) and the weak temperature dependency of Er in porous Si, which is similar to Er3+ in wide-bandgap semiconductors, suggests that Er is not in SiO2 or Si with bulk properties but, may be confined in Si light-emitting nanostructures. Porous Si is a good substrate for rare earth elements because: 1) a high concentration of optically active Er3+ can be obtained by implanting at about 200 keV, 2) porous Si and bulk Si are transparent to 1.54 μm emission therefore, device fabrication is simplified, and 3) although the external quantum efficiency of visible light from porous Si is compromised because of self-absorption, it can be used to pump Er3+.

Formation Mechanism of Microporous Silicon: Predictions and Experimental Results

1992 ◽  
Vol 283 ◽  
Author(s):  
V. Lehmann ◽  
U. Gösele
Keyword(s):  
Porous Silicon ◽  
Formation Mechanism ◽  
Quantum Confinement ◽  
Experimental Results ◽  
Porous Region ◽  
Formation Conditions ◽  
Porous Morphology

ABSTRACTRecently we presented a formation mechanism for micro-porous silicon which is based on a depletion of holes in the porous region due to quantum confinement. This theory allows predictions concerning the dependence of the porous morphology on the formation conditions. It is the purpose of this work to check whether these predictions are in accordance with experimental observations.

Relationships Between Photoluminescence Spectra and Porosity of Porous Silicon

1994 ◽  
Vol 332 ◽  
Author(s):  
H.Z. Song ◽  
L.Z. Zhang ◽  
B.R. Zhang ◽  
G.G. Qin
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Light Emission ◽  
Photoluminescence Spectra ◽  
Lower Side ◽  
Si Substrates ◽  
Peak Energy ◽  
P Type ◽  
Confinement Model

ABSTRACTIt was found that porous silicon (PS) layers formed on 0.01 Ωcm (111) and 0.02 Ωcm (100) Si substrates show high photoluminescence (PL) peak energies on both lower and higher porosity sides and a minimum of PL peak energy at the moderate porosity, while those formed on 0.8 and 10Ωcm (111) p-type Si substrates show an increase of PL peak energy with porosity on the lower side and a saturation of PL peak energy with porosity on the higher side. These experimental facts are not consistent with the quantum confinement model for light emission of PS, which predicts a monotonous increase of PL peak energy with PS porosity.

Effect of Preparation Conditions on the Silicon L-Edge In Electrochemically Prepared Porous Silicon

1993 ◽  
Vol 298 ◽  
Author(s):  
T. Van Buuren ◽  
T. Tiedje ◽  
W. Weydanz
Keyword(s):  
Electronic Structure ◽  
High Resolution ◽  
Porous Silicon ◽  
Quantum Confinement ◽  
Light Exposure ◽  
Blue Shift ◽  
Bulk Silicon ◽  
Preparation Conditions ◽  
P Type ◽  
Confinement Model

AbstractHigh resolution measurements of the silicon L-edge absorption in electrochemically prepared porous silicon show that the absorption threshold is shifted to higher energy relative to bulk silicon, and that the shift is dependent on how the porous silicon is prepared. When the porous silicon is made from n-type material with light exposure, the blue shift increases logarithmically with the anodizing current. Porous silicon prepared by anodizing p-type silicon exhibits a blue shift in the L-edge which increases with the time spent in the HF solution after the anodizing potential is turned off. The data are consistent with the quantum confinement model for the electronic structure of porous silicon.

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