scholarly journals Porous Silicon Gas Sensors: The Role of the Layer Thickness and the Silicon Conductivity

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4942 ◽  
Author(s):  
Francisco Ramírez-González ◽  
Godofredo García-Salgado ◽  
Enrique Rosendo ◽  
Tomás Díaz ◽  
Fabiola Nieto-Caballero ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Porous Layer ◽  
Silicon Layer ◽  
Ethanol Vapor ◽  
Porous Silicon Layer ◽  
Aluminum Electrode ◽  
Conductivity Type ◽  
Silicon Sensors ◽  
Metal Oxide Sensors

We studied the influences of the thickness of the porous silicon layer and the conductivity type on the porous silicon sensors response when exposed to ethanol vapor. The response was determined at room temperature (27 ∘C) in darkness using a horizontal aluminum electrode pattern. The results indicated that the intensity of the response can be directly or inversely proportional to the thickness of the porous layer depending on the conductivity type of the semiconductor material. The response of the porous sensors was similar to the metal oxide sensors. The results can be used to appropriately select the conductivity of semiconductor materials and the thickness of the porous layer for the target gas.

Double Sided Porous Silicon on Patterned Substrates for Thermal Effect Microsystems

2000 ◽  
Vol 657 ◽  
Author(s):  
S. Périchon ◽  
V. Lysenko ◽  
B. Remaki ◽  
D. Barbier
Keyword(s):  
Porous Silicon ◽  
Thermal Effect ◽  
Layer Thickness ◽  
Porous Layer ◽  
Silicon Layer ◽  
Current Density Distribution ◽  
Porous Silicon Layer ◽  
Monocrystalline Silicon ◽  
Porous Layers ◽  
Nanocrystallite Size

ABSTRACTApplication of porous silicon in thermal microsystem structures often requires the formation of deep localized porous silicon layers. The most commonly used method to prepare the porous layers is the dc anodic etching of monocrystalline silicon in a hydrofluoric acid (HF) based electrolyte. However inhomogeneity of the nanocrystallite size along the layer depth due to the decrease of HF concentration within the pores as well as the poor uniformity of the porous layer thickness limit the elaboration of deep porous layers. Thus we propose an original pulsed anodisation technique, using a double tank etching cell that allows localized porous silicon layers formation throughout the whole wafer thickness.Furthermore a selective double sided pulsed anodisation of silicon was performed on patterned silicon substrates. Porous silicon is formed in pre-determined parts of the wafer using composite polysilicon-silicon nitride masking layers. Technological solutions to get rid of porous layer thickness inhomogeneity due to non uniform current density distribution are discussed. Finally a toric porous silicon layer, crossing the whole silicon wafer, surrounding a 20 mm diameter monocrystalline silicon cylinder was successfully achieved ensuring a new approach of thermal insulation for thermal effect microsystems.

scholarly journals Effect of photo chemical etching and electro chemical etching on the topography of porous silicon wafers surfaces

2019 ◽  
Vol 24 (4) ◽  
pp. 52
Author(s):  
Amjad Hussein Jassem
Keyword(s):  
Porous Silicon ◽  
Layer Thickness ◽  
Porous Layer ◽  
Chemical Etching ◽  
Chemical Method ◽  
Pore Diameter ◽  
Electrochemical Etching ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Etching Time

In This research we study the effect of photo chemical etching and electrochemical etching on topography of porous silicon surfaces, the results showed that photo chemical etching produced roughness silicon layer which can have thickness be less of porous silicon layer which is produced by electro chemical etching When all the wafers have same etching time  and hydrofluoric solution (HF) concentration, the wafers have same resistance (10 Ω.cm). Also the results showed the roughness of porous silicon layers produced  by  electro chemical method which is bigger than the roughness of porous silicon layers produced by photo chemical method and the results of roughness of porous silicon layers, Pore diameter and porous layer thickness were produced by electro chemical method (1.55(µm) ((0.99(µm)) and ((1.21(µm) respectively), the results of roughness of porous silicon layers, Pore diameter and porous layer thickness were produced by photo chemical method 0.63)) nm -1.55)) (µm) ),so the (84.9 (nm)- and (3.94(nm) respectively . This is reinforces because of using the electro chemical to etching the wafer surf ace of bulk silicon and changing it to roughness silicon surface  be share in success of many practicalities.   http://dx.doi.org/10.25130/tjps.24.2019.072

HYDROGEN AND OXYGEN EVOLUTION WITH TEMPERATURE IN NANOPOROUS SILICON

2008 ◽  
Vol 15 (03) ◽  
pp. 261-264 ◽  
Author(s):  
A. MOUSSI ◽  
D. BOUHAFS ◽  
N. BENREGUIA ◽  
L. MAHIOU ◽  
M. S. BELKAID
Keyword(s):  
Porous Silicon ◽  
Ambient Temperature ◽  
Porous Layer ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Hydrogen Distribution ◽  
Chemical Route ◽  
Nanoporous Silicon ◽  
High Level ◽  
Secondary Ion

In this work, a porous layer on an n+ emitter by a chemical route was realized. The MEB observation shows a nanoporous shape of the surface. The subsequent contact depositions needs a heat treatment that has an influence on hydrogen and oxygen distributions in the porous layer. After heat treatments, the porous silicon layer is analyzed by secondary ion mass spectroscopy. The concentration profile of light elements like H , O , C , F and N are measured and compared with untreated porous layer. The results show that oxygen is present at high level at ambient temperature and then decreases from 25°C to 775°C. This means that oxygen desorption is observed on the surface. At 800°C the oxygen content increases again showing an oxidation of porous layer surface. For hydrogen, the concentration decreases from the ambient temperature until 750°C was noted. Then the hydrogen is restored at its first concentration. The FTIR spectra correlate this hydrogen distribution. The absorption spectra show the appearance of Si – H x bonds (with x = 1, 2, 3) at 2089, 2115, and 2140 cm-1, respectively. Both elements O and H are present deeply in the porous silicon layer as shown by the sputter time.

Effect of the Porous Silicon Layer Structure on Gas Adsorption

2020 ◽  
Vol 12 (4) ◽  
pp. 04020-1-04020-5
Author(s):  
A. P. Oksanich ◽  
◽  
S. E. Pritchin ◽  
M. A. Mashchenko ◽  
A. Yu. Bobryshev ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Gas Adsorption ◽  
Layer Structure ◽  
Silicon Layer ◽  
Porous Silicon Layer

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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