Investigation of optical anisotropy of refractive-index-profiled porous silicon employing generalized ellipsometry

1999 ◽  
Vol 14 (11) ◽  
pp. 4167-4175 ◽  
Author(s):  
S. Zangooie ◽  
R. Jansson ◽  
H. Arwin
Keyword(s):  
Porous Silicon ◽  
Optical Anisotropy ◽  
Optical Model ◽  
Crystalline Silicon ◽  
Electrochemical Etching ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Interface Roughness ◽  
Compositional Gradient ◽  
Time Modulation

Porosity depth profiles in porous silicon were realized by time modulation of the applied current density during electrochemical etching of crystalline silicon. The samples were investigated by variable angle spectroscopic ellipsometry. Using a basic optical model based on isotropy assumptions and the Bruggeman effective medium approximation, deviations from an ideal profile in terms of an interface roughness between the silicon substrate and the porous silicon layer and a compositional gradient normal to the surface were revealed. Furthermore, optical anisotropy of the sample was investigated by generalized ellipsometry. The anisotropy was found to be uniaxial with the optic axis tilted from surface normal by about 25°. The material was also found to exhibit positive birefringence.

Effects of Electrochemical Etching Time on the Performance of Porous Silicon Solar Cells on Crystalline n-Type (100) and (111)

2017 ◽  
Vol 46 ◽  
pp. 45-56 ◽  
Author(s):  
Khalid Omar ◽  
Khaldun A. Salman
Keyword(s):  
Solar Cells ◽  
Porous Silicon ◽  
Crystalline Silicon ◽  
Electrochemical Etching ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Silicon Solar Cells ◽  
Etching Time ◽  
Crystalline Silicon Solar Cells ◽  
Coating Layers

Electrochemical etching was carried out to produce porous silicon based on crystalline silicon n-type (100) and (111) wafers. Etching times of 10, 20, and 30 min were applied. Porous silicon layer was used as anti-reflection coating on crystalline silicon solar cells. The optimal etching time is 20 min for preparing porous silicon layers based on crystalline silicon n-type (100) and (111) wafers. Nanopores with high porosity were produced on the porous silicon layer based on crystalline silicon n-type (100) and (111) wafers with average diameters of 5.7 and 5.8 nm, respectively. Average crystallite sizes for the porous silicon layer based on crystalline silicon n-type (100) and (111) wafers were 20.57 and 17.45 nm at 20 and 30 min, respectively, due to the increase in broadening of the full width at half maximum. Photoluminescence peaks for porous silicon layers based on crystalline silicon n-type (100) and (111) wafers increased with growing porosity and a great blue shift in luminescence. The minimum effective coefficient of reflection was obtained from porous silicon layers based on the crystalline silicon n-type (100) wafer compared with n-type (111) wafer and as-grown at different etching times. Porous silicon layers based on the crystalline silicon n-type (100) wafer at 20 min etching time exhibited excellent light trapping at wavelengths ranging from 400 to 1000 nm. Thus, fabricated crystalline silicon solar cells based on porous silicon (100) anti-reflection coating layers achieved the highest efficiency at 15.50% compared to porous silicon (111) anti-reflection coating layers. The efficiency is characterized applying I-V characterization system under 100 mW/cm2 illumination conditions.

scholarly journals Porous silicon prepared by photo electrochemical etching assisted by laser

2019 ◽  
Vol 15 (32) ◽  
pp. 122-129
Author(s):  
Falah A-H Mutlak
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Crystalline Silicon ◽  
Electrochemical Etching ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Maximum Diameter ◽  
Face Centered Cubic ◽  
The Face ◽  
Face Centered

Porous silicon (PS) layers are prepared by anodization fordifferent etching current densities. The samples are thencharacterized the nanocrystalline porous silicon layer by X-RayDiffraction (XRD), Atomic Force Microscopy (AFM), FourierTransform Infrared (FTIR). PS layers were formed on n-type Siwafer. Anodized electrically with a 20, 30, 40, 50 and 60 mA/cm2current density for fixed 10 min etching times. XRD confirms theformation of porous silicon, the crystal size is reduced towardnanometric scale of the face centered cubic structure, and peakbecomes a broader with increasing the current density. The AFMinvestigation shows the sponge like structure of PS at the lowercurrent density porous begin to form on the crystalline silicon, whenthe current density increases, pores with maximum diameter areformed as observed all over the surface. FTIR spectroscopy shows ahigh density of silicon bonds, it is very sensitive to the surroundingambient air, and it is possible to oxidation spontaneously.

Preparation of Porous Silicon and Effect of Gettering on the Resistivity

2012 ◽  
Vol 476-478 ◽  
pp. 1794-1797 ◽  
Author(s):  
Su Xia Guo ◽  
Yi Tan ◽  
Jia Yan Li ◽  
Ya Qiong Li ◽  
Chen Guang Liu
Keyword(s):  
Porous Silicon ◽  
Raman Spectra ◽  
Pore Diameter ◽  
Crystalline Silicon ◽  
Electrochemical Etching ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

The porous silicon layer was fabricated by electrochemical etching process using an aqueous HF-based electrolyte. The characterizations of porous silicon layer were investigated by Emission-type scanning electron microscope (SEM), Raman spectra and X-ray diffraction (XRD). With the current density increasing, the pore diameter and density become much bigger. This result also was confirmed by Raman spectra and XRD result of samples, which revealed the decreasing of grain size of silicon. The resistivity of crystalline silicon increased when the porous layer was removed after heat treatment at 850°C for 2.5h, which should be attributed to the gettering process of porous silicon.

I-V and Surface Topography Study of Nanostructure Porous Silicon Layer Prepared by Electrochemical Etching

2012 ◽  
Vol 576 ◽  
pp. 519-522 ◽  
Author(s):  
Fadzilah Suhaimi Husairi ◽  
Maslihan Ain Zubaidah ◽  
Shamsul Faez M. Yusop ◽  
Rusop Mahmood Mohamad ◽  
Saifolah Abdullah
Keyword(s):  
Electrical Properties ◽  
Porous Silicon ◽  
Surface Topography ◽  
Electrochemical Etching ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Force Microscopy ◽  
Atomic Force ◽  
Current Voltage ◽  
P Type

This article reports on the electrical properties of porous silicon nanostructures (PSiNs) in term of its surface topography. In this study, the PsiNs samples were prepared by using different current density during the electrochemical etching of p-type silicon wafer. PSiNs has been investigated its electrical properties and resistances for different surface topography of PSiNs via current-voltage (I-V) measurement system (Keithley 2400) while its physical structural properties was investigated by using atomic force microscopy (AFM-XE100).

scholarly journals CONTROL OVER THE PERFORMANCE OF MONOCRYSTALLINE SILICON SOLAR CELLS REFERRING TO THE POROUS SILICON LAYER / MONOKRISTALINIO SILICIO SAULĖS ELEMENTŲ CHARAKTERISTIKŲ VALDYMAS AKYTOJO SILICIO SLUOKSNIU

2012 ◽  
Vol 3 (6) ◽  
pp. 91-94
Author(s):  
Ramūnas Mitkevičius ◽  
Viktor Zagadskij ◽  
Eugenijus Šatkovskis
Keyword(s):  
Solar Cells ◽  
Porous Silicon ◽  
Output Power ◽  
Crystalline Silicon ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Silicon Solar Cells ◽  
Crystalline Silicon Solar Cells ◽  
Maximal Output Power ◽  
Maximal Output

The paper examines the parameters of crystalline silicon solar cells such as fill factor, maximal output power and series resistance forming a porous silicon layer. The obtained results show that introducing the layer into the structure of a solar cell results in a 19 percent enhancement of maximal output power and conversion efficiency. Santrauka Šiame darbe tiriamas akytojo silicio darinių poveikis saulės elementų elektrinėms charakteristikoms: nuosekliajai varžai, voltamperinių charakteristikų formai. Parodyta, kad pagaminus silicio saulės elemente akytojo silicio sluoksnį, galima veikti (valdyti) saulės elementų voltamperines charakteristikas ir elemento nuosekliąją elektrinę varžą. Nustatyta, kad tiriamajame bandinyje suformavus akytojo silicio sluoksnį, apkrovos voltamperinės charakteristikos užpildos rodiklis padidėjo 1,15 karto, o maksimali elemento kuriama ir apkrovos metu atiduodama elektros energijos galia – 1,19 karto. Tiek pat 1,19 karto padidėjo saulės elemento šviesos konversijos į elektros energiją efektyvumas.

scholarly journals Fabrication and Characterization of Porous Silicon Layer Prepared by Photo-Electrochemical Etching in CH3OH:HF Solution

2013 ◽  
Vol 8 ◽  
pp. 29-36 ◽  
Author(s):  
Hasan A. Hadi ◽  
Raid A. Ismail ◽  
Nadir F. Habubi
Keyword(s):  
Porous Silicon ◽  
Electrochemical Etching ◽  
Gravimetric Method ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Constant Current ◽  
Theoretical Relation ◽  
Fabrication And Characterization ◽  
A Current

Porous silicon (PS) has been fabricated by Photo-electrochemical etching. Porous silicon was anodized on n-type Si in light using a current density of 20 mA/cm2 for 10 min. The porous structure formation was confirmed using XRD and AFM studies. The root mean square (RMS) roughness of the Porous silicon layer is found to be around 47.5 nm and the ten point height was 317 nm. The average of pores diameter was 419.98nm, and the grain growth is columnar with a (211) preferred orientation. The grain size of the PS was estimated from the Scherer’s formula and found to be 73 nm. All the properties of the porous silicon layer, such as porosity and the thickness depend on the anodization parameters. The porosity (P) was approximately 77%. The thickness of the layer formed during an anodization in constant current was 3.54 nm in gravimetric method, while its value was 1.77 nm by using the theoretical relation.

Effect of Etching Time on Electrical and Optical Properties of Porous Silicon

2013 ◽  
Vol 667 ◽  
pp. 397-401
Author(s):  
S.F.M. Yusop ◽  
N. Azaman ◽  
Hartini Ahmad Rafaie ◽  
S. Amizam ◽  
Saifollah Abdullah ◽  
...  
Keyword(s):  
Optical Properties ◽  
Porous Silicon ◽  
Electrochemical Etching ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Constant Current ◽  
Voltage Source ◽  
Etching Time ◽  
Constant Current Density ◽  
Wafer Substrate

The characterized on porous silicon layer by using photoluminescence (PL) and I-V measurement (I-V) has been done. Porous silicon was formed by electrochemical etching on (100) p-type Si wafer substrate with the constant current density (20mA/cm2) and variable the etching time. The samples ware prepared under various etching time and properties of porous silicon depend on an etching time. Porous silicon has been used in humidity sensors to detect humidity through changes of its electrical properties. The samples of porous silicon were characterized by using Photoluminescence Spectroscopy (PL) that used to characterize optical properties while I-V Measurement (I-V) used to characterize porous silicon junction properties using a linear voltage source. The result shows PL intensity is increase while the wavelength is decrease for etching time of PSi is longer. For the I-V measurement result shows the etching time affect the resistance of sample due to its porosity.

scholarly journals Modification of Surface Properties of Silicon Wafers by Laser-Assisted Electrochemical Etching

2018 ◽  
Vol 80 ◽  
pp. 30-39
Author(s):  
Hasan A Hadi
Keyword(s):  
Porous Silicon ◽  
Optical Microscopy ◽  
Surface Topography ◽  
Electrochemical Etching ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Diffraction Peak ◽  
Etching Time ◽  
Layer Formation ◽  
Xrd Patterns

In this paper, the structural properties of porous silicon layer PSL were reported. Photo-assisted (laser) electrochemical etching PECE technique used to fabrication PSL from n-type wafer silicon as a function of etching time. Optical microscopy OM image is confirmed that the surface topography of porous silicon layer formation was a mud-like structure. The porosity and thickness have been determined gravimetrically are varied from 61% to 82% and 7.2 µm to 9.4µm respectively. The XRD patterns show that one diffraction peak for all PSL through anodization duration and it is assigned to the (400) plane and data confirmed the porous silicon PS was nanocrystalline.

scholarly journals The Effect of Etching Time On Structural Properties of Porous Quaternary AlInGaN Thin Films

2021 ◽  
Vol 19 (50) ◽  
pp. 77-83
Author(s):  
Ghasaq Ali Tomaa ◽  
Alaa Jabbar Ghazai
Keyword(s):  
Porous Silicon ◽  
Crystal Size ◽  
Electrochemical Etching ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Etching Time ◽  
Etching Technique ◽  
Force Microscopy ◽  
Atomic Force ◽  
Homogeneous Pattern

Using photo electrochemical etching technique (PEC), porous silicon (PS) layers were produced on n-type silicon (Si) wafers to generate porous silicon for n-type with an orientation of (111) The results of etching time were investigated at: (5,10,15 min). X-ray diffraction experiments revealed differences between the surface of the sample sheet and the synthesized porous silicon. The largest crystal size is (30 nm) and the lowest crystal size is (28.6 nm) The analysis of Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscope (FESEM) were used to research the morphology of porous silicon layer. As etching time increased, AFM findings showed that root mean square (RMS) of roughness and porous silicon grain size decreased and FESEM showed a homogeneous pattern and verified the formation of uniform porous silicon.

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