Analysis of the Structure of Light-emitting Porous Silicon by Raman Scattering

1991 ◽  
Vol 256 ◽  
Author(s):  
Zhifeng Sui ◽  
Patrick P. Leong ◽  
Irving P. Herman ◽  
Gregg S. Higashi ◽  
Henryk Temkin
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Crystalline Silicon ◽  
Silicon Film ◽  
Characteristic Dimension ◽  
Raman Shift ◽  
Phonon Confinement ◽  
Island Size ◽  
Light Emitting ◽  
Silicon Islands

AbastracRaman spectra from a thick porous silicon film (∼100 μm) that strongly emits in the visible (∼ 6350 Å) at room temperature are obtained. An asymmetric peak with a Raman shift of ∼ 508 - 510 cm−1 and a width of ∼ 40 cm−1 is seen in every spectrum. This Raman feature resembles that of μc-Si, suggesting that the local structure of the porous silicon is a network of interconnected crystalline silicon islands with the island size in the nanometer range., and that the, shape of the islands is more sphere-like than rod-like. The characteristic dimension of the islands in these porous silicon films is estimated to be ∼ 2.5 - 3.0 nm on the basis of an empirical model calculation of phonon confinement.

Light Emission from Intrinsic and Doped Silicon-Rich Silicon Oxide: from the Visible to 1.6 ΜM

1996 ◽  
Vol 452 ◽  
Author(s):  
L. Tsybeskov ◽  
K. L. Moore ◽  
P. M. Fauchet ◽  
D. G. Hall
Keyword(s):  
Rare Earth ◽  
External Quantum Efficiency ◽  
Room Temperature ◽  
Structural Modification ◽  
Silicon Oxide ◽  
Light Emission ◽  
Crystalline Silicon ◽  
Light Emitting ◽  
Infra Red ◽  
Doped Silicon

AbstractSilicon-rich silicon oxide (SRSO) films were prepared by thermal oxidation (700°C-950°C) of electrochemically etched crystalline silicon (c-Si). The annealing-oxidation conditions are responsible for the chemical and structural modification of SRSO as well as for the intrinsic light-emission in the visible and near infra-red spectral regions (2.0–1.8 eV, 1.6 eV and 1.1 eV). The extrinsic photoluminescence (PL) is produced by doping (via electroplating or ion implantation) with rare-earth (R-E) ions (Nd at 1.06 μm, Er at 1.5 μm) and chalcogens (S at ∼1.6 μm). The impurities can be localized within the Si grains (S), in the SiO matrix (Nd, Er) or at the Si-SiO interface (Er). The Er-related PL in SRSO was studied in detail: the maximum PL external quantum efficiency (EQE) of 0.01–0.1% was found in samples annealed at 900°C in diluted oxygen (∼ 10% in N2). The integrated PL temperature dependence is weak from 12K to 300K. Light emitting diodes (LEDs) with an active layer made of an intrinsic and doped SRSO are manufactured and studied: room temperature electroluminescence (EL) from the visible to 1.6 μmhas been demonstrated.

Manufacture of Submicron Light-Emitting Porous Silicon Areas for Miniature LEDs

1995 ◽  
Vol 380 ◽  
Author(s):  
S. P. Duttagupta ◽  
C. Peng ◽  
L. Tsybeskov ◽  
P. M. Fauchet
Keyword(s):  
Electron Beam ◽  
Porous Silicon ◽  
Crystalline Silicon ◽  
Group Formation ◽  
Nanometer Scale ◽  
Ion Milling ◽  
Light Emitting ◽  
Atomic Force ◽  
Mapping Techniques ◽  
Trilayer Process

ABSTRACTWe have investigated several methods to form submicron-size porous silicon regions. Porous silicon can emit light from the violet to past 1.5 μm with high photoluminescence efficiency at room temperature. It is composed of a high density of nanometer-scale crystalline silicon wires or dots. To integrate light-emitting porous silicon (LEPSi) LEDs with conventional Si microelectronics, it is necessary to produce miniature LEPSi regions adjacent to fully protected crystalline silicon regions. These techniques can be divided into two groups. In the first group formation of LEPSi is prevented during electrochemistry. Using optical and electron beam lithography, and a trilayer process with silicon nitride or amorphization by ion-implantation, we have made LEPSi patterns as small as 100 nm. In the second group, the formation of LEPSi during electrochemistry is enhanced by ion-milling or reactive ion-etching which we have found to help the pore nucleation. We have used a variety of mapping techniques, such as photoluminescence, atomic force and electron beam microscopies, to characterize the sharpness of the interface between the porous silicon and crystalline silicon regions.

scholarly journals Influence of applied current density on the nanostructural and light emitting properties of n-type porous silicon

2015 ◽  
Vol 29 (15) ◽  
pp. 1550093 ◽  
Author(s):  
A. Cetinel ◽  
N. Artunç ◽  
G. Sahin ◽  
E. Tarhan
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Pore Diameter ◽  
Crystalline Silicon ◽  
Peak Shift ◽  
Raman Peak ◽  
Light Emitting ◽  
Nanocrystallite Size ◽  
Raman Peak Shift ◽  
Pore Depth

Effects of current density on nanostructure and light emitting properties of porous silicon (PS) samples were investigated by field emission scanning electron microscope (FE-SEM), gravimetric method, Raman and photoluminescence (PL) spectroscopy. FE-SEM images have shown that below 60 mA/cm 2, macropore and mesopore arrays, exhibiting rough morphology, are formed together, whose pore diameter, pore depth and porosity are about 265–760 nm, 58–63 μ m and 44–61%, respectively. However, PS samples prepared above 60 mA/cm 2 display smooth and straight macropore arrays, with pore diameter ranging from 900–1250 nm, porosity of 61–80% and pore depth between 63–69 μ m . Raman analyses have shown that when the current density is increased from 10 mA/cm 2 to 100 mA/cm 2, Raman peaks of PS samples shift to lower wavenumbers by comparison to crystalline silicon (c-Si). The highest Raman peak shift is found to be 3.2 cm -1 for PS sample, prepared at 90 mA/cm 2, which has the smallest nanocrystallite size, about 5.2 nm. This sample also shows a pronounced PL, with the highest blue shifting, of about 12 nm. Nanocrystalline silicon, with the smallest nanocrystallite size, confirmed by our Raman analyses using microcrystal model (MCM), should be responsible for both the highest Raman peak shift and PL blue shift due to quantum confinement effect (QCE).

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+.

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.

scholarly journals EFFECT OF PHONON CONFINEMENT AND STRAIN ON RAMAN SPECTRA FROM LIGHT-EMITTING POROUS SILICON

1994 ◽  
Vol 43 (3) ◽  
pp. 494
Author(s):  
YANG MIN ◽  
HUANG DA-MING ◽  
HAO PING-HAI ◽  
ZHANG FU-LONG ◽  
HOU XIAO-YUAN ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Raman Spectra ◽  
Phonon Confinement ◽  
Light Emitting

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.

Single Crystalline SOI Square Islands Fabricated by Laser Recrystallization Using a Surrounding Antireflection Cap and Successive Self-Aligned Isolation Utilizing the Same Cap

1984 ◽  
Vol 35 ◽  
Author(s):  
R. Mukai ◽  
N. Sasaki ◽  
T. Iwai ◽  
S. Kawamura ◽  
M. Nakano
Keyword(s):  
Grain Boundary ◽  
Laser Beam ◽  
Grain Boundaries ◽  
Crystalline Silicon ◽  
Silicon Film ◽  
High Density ◽  
Single Crystalline Silicon ◽  
Single Crystalline ◽  
Laser Recrystallization ◽  
Silicon Islands

ABSTRACTA new laser recrystallizing technique has been developedfor high density SOI-LSI's. This technique produces single crystalline silicon islands on an amorphous insulating layerwithout seed. Square windows are opened at arbitrary places in an antireflection cap over a polycrystalline film on an amorphous insulatinq layer. Grain boundaries of the polycrystalline Si in the window are removed completely at the subsequent laser-recrystallization step. Single crystalline silicon islands are formed by self-aligned etching of silicon film which was covered by the antireflection cap. This technique is an effective method for fabricating high density SOI-LSI's, since the singlecrystalline islands can be fabricated at arbitrarily selected places. Yield of the grain-boundary-free islands was 95% the size of the island is 1O x 20μm, and the irradiation oyerlap of laser-beam traces is 70%.

Fabrication and Characterization of Light Emitting Porous Silicon and Polymer Nanocomposites

1996 ◽  
Vol 452 ◽  
Author(s):  
S. P. Duttagupta ◽  
P. M. Fauchet ◽  
X. L. Chen ◽  
S. A. Jenekhe
Keyword(s):  
Thermal Conductivity ◽  
Porous Silicon ◽  
Room Temperature ◽  
In Situ Polymerization ◽  
Pore Filling ◽  
Light Emitting ◽  
Polymer Molecules ◽  
Fabrication And Characterization

AbstractWe report the fabrication of nanocomposites by the infiltration of polymers into porous silicon. Polymers such as polyamide, polystyrene, PMMA, and PVC were chosen because they are commonly available and have been extensively studied. The pore-filling was accomplished by either diffusion of the polymer molecules into porous silicon or in-situ polymerization of the monomer. The Vickers hardness arid the thermal conductivity of the samples were measured. There was a difference in the nanocomposite characteristics depending on whether the samples were as-anodized or had been annealed in oxygen. By infiltrating polyamide into an as-anodized sample, a 42% increase in hardness and a 24% increase in thermal conductivity were observed at room temperature, without any degradation of luminescence.

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