scholarly journals In Situ Growth of ZnO inside a Porous Silicon Matrix Obtained by Electrochemical Etching with a Hydrofluoric Acid-Formaldehyde Solution

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
R. Juárez-Nahuatlato ◽  
G. García ◽  
M. Pacio ◽  
Roberto Portillo ◽  
N. Perez-Amaro ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Hydrofluoric Acid ◽  
Electrochemical Etching ◽  
Nitrogen Adsorption ◽  
Ultraviolet Region ◽  
Ultraviolet Emission ◽  
Silicon Matrix ◽  
Electrolytic Process ◽  
Band Emission ◽  
Before And After

We present zinc oxide (ZnO) particles obtained inside a porous silicon matrix in the same electrolytic process using a p-type silicon wafer in a hydrofluoric acid (HF) solution containing formaldehyde (CH2O) and hydrated zinc sulfate as additives. The X-ray diffraction pattern of the sample confirmed the presence of ZnO with a hexagonal-type wurtzite structure. Photoluminescence (PL) spectra of the samples, before and after the functionalization process, were measured to observe the effect of ZnO inside the porous silicon. The PL measurements of porous silicon functionalized with ZnO (ZnO/PS) revealed infrared, red, blue, and ultraviolet emission bands. The ultraviolet region corresponds to the band-band emission of ZnO, and the visible emission is attributed to defects. The results of the nitrogen adsorption/desorption isotherms of the PS and ZnO/PS samples revealed larger BET surface areas and pore diameters for the ZnO/PS sample. We conclude that ZnO/PS can be obtained in a one-step electrolytic process. These types of samples can be used in gas sensors and photocatalysis.

scholarly journals Study of Composite Structures Based on a Porous Silicon Matrix and Nanoparticles Ag/Zno Used as Non-Invasive Highly Sensitive Biosensor Devices

2021 ◽  
Author(s):  
Veniamin Koshevoi ◽  
Anton Belorus ◽  
Ilya Pleshanov ◽  
Anton Timchenko ◽  
Roman Denisenko ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Hydrofluoric Acid ◽  
Emission Spectroscopy ◽  
Composite Structures ◽  
Electrochemical Etching ◽  
Silicon Matrix ◽  
Non Invasive ◽  
Highly Sensitive ◽  
Porous Matrices ◽  
Scanning Electron

In this work composite structures based on a porous silicon were obtained and studied. Porous matrices were formed by electrochemical etching in aqueous solutions of hydrofluoric acid. Based on the obtained substrates, por-silicon (Si)/silver (Ag) and por-Si/zinc oxide (ZnO) composite structures were formed. These composites were functionalized by various methods (electro (E)-, thermo (T)-, electrothermal exposure) as a result of which the structures were modified. When studying the samples by scanning electron microscopy (SEM), it was concluded that silver nanoparticles actively diffused into the pores under these technological modes of functionalization. The por-Si/Ag and por-Si/ZnO composite structures were also studied using the following methods: infrared (IR) spectroscopy and Raman ultrasoft X-ray emission spectroscopy. Also, the photoluminescent characteristics of the samples were studied. Based on the obtained results, it was concluded that functionalization methods actively change the phase composition of structures and the optical properties of composites.

Surface Engineered Porous Silicon-based Nanostructures for Cancer Therapy

2012 ◽  
Vol 1416 ◽  
Author(s):  
Adi Tzur-Balter ◽  
Naama Massad-Ivanir ◽  
Ester Segal
Keyword(s):  
Porous Silicon ◽  
Surface Chemistry ◽  
Electrochemical Etching ◽  
Release Kinetics ◽  
Drug Carrier ◽  
Drug Loading ◽  
Nitrogen Adsorption ◽  
Cancer Drug ◽  
Cytotoxicity Studies

ABSTRACTIn this work, nanostructured porous silicon (PSi) hosts, synthesized by electrochemical etching of Si, are designed to carry and release the anti cancer drug, mitoxantrone dihydrochloride (MTX). We study the effect of surface chemistry of the Si scaffold on its properties as a drug carrier. The freshly-etched PSi is modified by surface alkylation using thermal hydrosilylation with 1-dodecene. Fourier-transform infrared spectroscopy and nitrogen adsorption-desorption measurements are employed to characterize the PSi carriers after chemical modification. Both, drug loading efficiency and release kinetics are found to be significantly affected by surface chemistry of the PSi. In vitro cytotoxicity studies on human breast carcinoma (MDA-MB-231) cells show that the MTX released from the PSi hosts maintains its cytotoxic functionality.

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.

scholarly journals PHOTOSENSITIVE MATRIX BASED ON POROUS MICROCRYSTALLINE SILICON

2017 ◽  
Vol 17 (5) ◽  
pp. 115-121
Author(s):  
N.V. Latukhina ◽  
D.A. Pisarenko ◽  
A.V. Volkov ◽  
V.A. Kitaeva
Keyword(s):  
Porous Silicon ◽  
Hydrofluoric Acid ◽  
Electrochemical Etching ◽  
Etching Process ◽  
Microcrystalline Silicon ◽  
Artificial Retina ◽  
Experimental Researches ◽  
Water Alcohol Solutions ◽  
Water Alcohol

The article presents the results of experimental researches of optoelectric properties of porous silicon. Layers of porous silicon were formed using electrochemical etching process in water-alcohol solutions of hydrofluoric acid on plates with a pre-established microrelief surface. Evaluation of possibility of using of created structure as the artificial retina component was performed based on the results of the research.

POROUS SILICON: INFLUENCE OF ETCHING TEMPERATURE ON MICROSTRUCTURE AND LUMINESCENCE

2001 ◽  
Vol 08 (05) ◽  
pp. 429-433 ◽  
Author(s):  
D. J. BLACKWOOD ◽  
Y. ZHANG
Keyword(s):  
Porous Silicon ◽  
Light Source ◽  
Hydrofluoric Acid ◽  
Uv Light ◽  
Electrochemical Etching ◽  
Light Emitting ◽  
Influence Of Temperature ◽  
Etching Solution ◽  
Experimental Parameters

Electrochemical etching in solutions based on hydrofluoric acid has been widely used to form light-emitting porous silicon. However, the effects of a number of the experimental parameters on the quality of the porous silicon produced have yet to be fully investigated. In the present paper the influence of temperature and viscosity of the etching solution is evaluated in terms of the morphology and porosity of the porous silicon produced as well as the wavelength of the photoluminescence or electroluminescence subsequently emitted. It was found that under stimulation from a UV light source the wavelength of the photoluminescence emitted from the porous silicon films blueshifted with decreasing etching temperature. SEM and AFM investigations revealed that this blueshifting of the photoluminescence resulted from the production of smaller nanocrystals at the lower etching temperatures.

Residual Stress Measurement of Porous Silicon Thin Film by Substrate Curvature Method

2006 ◽  
Vol 326-328 ◽  
pp. 223-226
Author(s):  
Yu Xian Di ◽  
Xin Hua Ji ◽  
Ming Hu ◽  
Yu Wen Qin ◽  
Jin Long Chen
Keyword(s):  
Residual Stress ◽  
Porous Silicon ◽  
Stress Measurement ◽  
Electrochemical Etching ◽  
Intrinsic Stress ◽  
Residual Tensile Stress ◽  
Porous Films ◽  
Silicon Thin Film ◽  
Before And After ◽  
Substrate Curvature

Extensive research has been done on porous silicon (PS) and its applications in optoelectronics since the discovery of its light emitting properties. Porous silicon technology is also used for silicon micro machining. However, porous films can be seriously strained and this often causes mechanical curling, fracture and device failures. In the present study an optical apparatus based on substrate curvature method was developed for intrinsic stress measurement of thin films, which offered a lot of advantages as overall field, non-contact, high precision, nondestructive, easy operation and quick response. Using the apparatus, the residual stress in porous silicon layers prepared by electrochemical etching was obtained. The residual stresses in the films were determined by measuring the curvature of the Si substrate before and after etching. It is found that the residual tensile stress tends to increase with the porosity increasing and the doping concentration of the silicon wafer increasing. The results show that there is a deep connection between the microstructure PS and the residual stress distribution.

Effect of Carbon Pre-Treatment on Pd Dispersion in Synthesis of Pd/C Catalyst

2014 ◽  
Vol 804 ◽  
pp. 149-152 ◽  
Author(s):  
Ji Sun Kim ◽  
Jae Ho Baek ◽  
Myung Hwan Kim ◽  
Seong Soo Hong ◽  
Man Sig Lee
Keyword(s):  
Surface Area ◽  
Nitrogen Adsorption ◽  
Area Ratio ◽  
High Dispersion ◽  
Co Chemisorption ◽  
Pd Dispersion ◽  
Before And After ◽  
Pre Treatment ◽  
Treated Carbon ◽  
Adsorption Desorption

In this study, we confirmed effect of carbon pre-treatment on Pd dispersion in synthesis of Pd/C catalyst. Physical characteristics on the surface of before and after pre-treated carbon were analyzed by nitrogen adsorption-desorption analysis. The dispersion and size of Pd particles were analyzed by XRD, FE-TEM and CO-chemisorption. After pre-treatment, surface area of carbon were decreased. And mesopore area ratio were increased with decreasing micropore area ratio. In the case of pre-treated carbon, we confirmed high dispersion of Pd particles.

Quantum Confinement Effects on the Dielectric Constant of Porous Silicon

1992 ◽  
Vol 283 ◽  
Author(s):  
R. Tsu ◽  
L. Ioriatti ◽  
J. F. Harvey ◽  
H. Shen ◽  
R. A. Lux
Keyword(s):  
Dielectric Constant ◽  
Porous Silicon ◽  
Size Effects ◽  
Quantum Confinement ◽  
Electrochemical Etching ◽  
Index Of Refraction ◽  
Quantum Size Effects ◽  
Quantum Size ◽  
Quantum Confinement Effects ◽  
Shallow Impurities

ABSTRACTThe reduction of the dielectric constant due to quantum confinement is studied both experimentally and theoretically. Angle resolved ellipsometry measurements with Ar- and He-Ne-lasers give values for the index of refraction far below what can be accounted for from porosity alone. A modified Penn model to include quantum size effects has been used to calculate the reduction in the static dielectric constant (ε) with extreme confinement. Since the binding energy of shallow impurities depends inversely on ε2, the drastic decrease in the carrier concentration as a result of the decrease in ε leads to a self-limiting process for the electrochemical etching of porous silicon.

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