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.

Oxidized porous silicon as a non-interfering support for luminescent dyes

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
G. Santamaría-Juárez ◽  
E. Gómez-Barojas ◽  
E. Quiroga-González ◽  
E. Sánchez-Mora ◽  
J. A. Luna-López
Keyword(s):  
Experimental Study ◽  
Porous Silicon ◽  
Low Temperature ◽  
Thermal Oxidation ◽  
Surface States ◽  
Large Contribution ◽  
Porous Si ◽  
Host Matrix ◽  
Oxidized Porous Silicon ◽  
Pl Spectrum

AbstractThe objective of this work is to elucidate the possibility to passivate the surface states of porous Si (PSi) by thermal oxidation to be used as a passive host matrix. It is known that a large contribution to the Photoluminescence (PL) of PSi comes from defects at the surface. This PL could overlap the PL of guest materials making it difficult to identify the details of the PL spectrum of the guest. We report on an experimental study about the effect of thermal oxidation at low temperature on the PL of PSi and on the functionalization of oxidized PSi with fluorescein. The background PL is minimized allowing a better detection of fluorescein molecules adsorbed on oxidized PSi.

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.

Comparative Optical Studies of Chemically Synthesized Silicon Nanocrystals

1996 ◽  
Vol 452 ◽  
Author(s):  
Gildardo R. Delgado ◽  
Howard W.H. Lee ◽  
Susan M. Kauzlarich ◽  
Richard A. Bley
Keyword(s):  
Porous Silicon ◽  
Silicon Nanocrystals ◽  
Surface Passivation ◽  
Theoretical Calculations ◽  
Dominant Role ◽  
Blue Emission ◽  
Surface States ◽  
Si Nanocrystals ◽  
Optical And Electronic Properties ◽  
Passivation Layers

AbstractWe studied the optical and electronic properties of silicon nanocrystals derived from two distinct fabrication procedures. One technique uses a controlled chemical reaction. In the other case, silicon nanocrystals are produced by ultrasonic fracturing of porous silicon layers. We report on the photoluminescence, photoluminescence excitation, and absorption spectroscopy of various size distributions derived from these techniques. We compare the different optical properties of silicon nanocrystals made this way and contrast them with that observed in porous silicon. Our results emphasize the dominant role of surface states in these systems as manifested by the different surface passivation layers present in these different fabrication techniques. Experimental absorption measurements are compared to theoretical calculations with good agreement. Our results provide compelling evidence for quantum confinement in both types of Si nanocrystals. Our results also indicate that the blue emission from very small Si nanocrystals corresponds to the bandedge emission, while the red emission arises from traps.

Prevention of InP/InGaAs/InP Double Heterojunction Bipolar Transistors from Current Gain Reduction during Passivation

2004 ◽  
Vol 833 ◽  
Author(s):  
Byoung-Gue Min ◽  
Jong-Min Lee ◽  
Seong-Il Kim ◽  
Chul-Won Ju ◽  
Kyung-Ho Lee
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Silicon Oxide ◽  
Surface Recombination ◽  
Surface States ◽  
Bipolar Transistors ◽  
Base Layer ◽  
Current Gain ◽  
Device Structure ◽  
Double Heterojunction ◽  
Gain Reduction

ABSTRACTA significant degradation of current gain of InP/InGaAs/InP double heterojunction bipolar transistors was observed after passivation. The amount of degradation depended on the degree of surface exposure of the p-type InGaAs base layer according to the epi-structure and device structure. The deposition conditions such as deposition temperature, kinds of materials (silicon oxide, silicon nitride and aluminum oxide) and film thickness were not major variables to affect the device performance. The gain reduction was prevented by the BOE treatment before the passivation. A possible explanation of this behavior is that unstable non-stoichiometric surface states produced by excess In, Ga, or As after mesa etching are eliminated by BOE treatment and reduce the surface recombination sites.

Performance and characteristics of double layer porous silicon oxide resistance random access memory

2013 ◽  
Vol 102 (25) ◽  
pp. 253509 ◽  
Author(s):  
Tsung-Ming Tsai ◽  
Kuan-Chang Chang ◽  
Rui Zhang ◽  
Ting-Chang Chang ◽  
J. C. Lou ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Double Layer ◽  
Silicon Oxide ◽  
Random Access ◽  
Random Access Memory ◽  
Access Memory ◽  
Resistance Random Access Memory

Enhancement of efficiency in graphene/porous silicon solar cells by co-doping graphene with gold nanoparticles and bis(trifluoromethanesulfonyl)-amide

2017 ◽  
Vol 5 (35) ◽  
pp. 9005-9011 ◽  
Author(s):  
Ju Hwan Kim ◽  
Dong Hee Shin ◽  
Ha Seung Lee ◽  
Chan Wook Jang ◽  
Jong Min Kim ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Solar Cells ◽  
Porous Silicon ◽  
Au Nanoparticles ◽  
Silicon Solar Cells ◽  
Porous Si ◽  
Co Doping ◽  
Si Solar Cells ◽  
First Time

The co-doping of graphene with Au nanoparticles and bis(trifluoromethanesulfonyl)-amide is employed for the first time to enhance the performance of graphene/porous Si solar cells.

Valence-Mending Passivation of Si(100) Surface: Principle, Practice and Application

2015 ◽  
Vol 242 ◽  
pp. 51-60 ◽  
Author(s):  
Meng Tao
Keyword(s):  
Transition Metal ◽  
Schottky Barrier Height ◽  
New Records ◽  
Transition Metal Dichalcogenides ◽  
Surface States ◽  
Atomic Layer ◽  
Schottky Barriers ◽  
Photovoltaic Devices ◽  
Dangling Bonds ◽  
Metal Dichalcogenides

Surface states have hindered and degraded many semiconductor devices since the Bardeen era. Surface states originate from dangling bonds on the surface. This paper discusses a generic solution to surface states, i.e. valence-mending passivation. For the Si (100) surface, a single atomic layer of valence-mending sulfur, selenium or tellurium can terminate ~99% of the dangling bonds, while group VII fluorine or chlorine can terminate the remaining 1%. Valence-mending passivation of Si (100) has been demonstrated using CVD, MBE and solution passivation. The keys to valence-mending passivation include an atomically-clean Si (100) surface for passivation and precisely one monolayer of valence-mending atoms on the surface. The passivated surface exhibits unprecedented properties. Electronically the Schottky barrier height between various metals and valence-mended Si (100) now follows more closely the Mott-Schottky theory. With metals of extreme workfunctions, new records for low and high Schottky barriers are created on Si (100). The highest barrier so far is 1.14 eV, i.e. a larger-than-bandgap barrier, and the lowest barrier is below 0.08 eV and potentially negative. Chemically silicidation between metal and valence-mended Si (100) is suppressed up to 500 °C, and the thermally-stable record Schottky barriers enable their applications in nanoelectronic, optoelectronic and photovoltaic devices. Another application is transition metal dichalcogenides. Valence-mended Si (100) is an ideal starting surface for growth of dichalcogenides, as it provides only van der Waals bonding to the dichalcogenide.

Visible Electro- and Photoluminescence from Porous Silicon and its Related Optoelectronic Properties

1991 ◽  
Vol 256 ◽  
Author(s):  
Nobuyoshi Koshida ◽  
Hideki Koyama
Keyword(s):  
Porous Silicon ◽  
Optical Absorption ◽  
Size Effect ◽  
Band Gap ◽  
Visible Region ◽  
Optoelectronic Properties ◽  
Porous Si ◽  
Quantum Size ◽  
Effect Model ◽  
Injection Type

ABSTRACTThe optoelectronic properties of porous Si (PS) are presented in terms of electroluminescence (EL), photoluminescence (PL), photoconduction (PC), and optical absorption. Observations of injection-type EL, efficient PL, band-gap widening, and photosensitivities In the visible region are consistent with the quantum size effect model in PS.

scholarly journals Morphology and FT IR spectra of porous silicon

2017 ◽  
Vol 68 (7) ◽  
pp. 53-57 ◽  
Author(s):  
Martin Kopani ◽  
Milan Mikula ◽  
Daniel Kosnac ◽  
Jan Gregus ◽  
Emil Pincik
Keyword(s):  
Porous Silicon ◽  
Ir Spectra ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Layer Formation ◽  
Porous Si ◽  
Ft Ir ◽  
P Type ◽  
Type Sample ◽  
Ftir Investigation

AbstractThe morphology and chemical bods of p-type and n-type porous Si was compared. The surface of n-type sample is smooth, homogenous without any features. The surface of p-type sample reveals micrometer-sized islands. FTIR investigation reveals various distribution of SiOxHycomplexes in both p-and n-type samples. From the conditions leading to porous silicon layer formation (the presence of holes) we suggest both SiOxHyand SiFxHycomplexes in the layer.

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