الفهرس 
Theoretical background and literature reviewOnly 14 pages are availabe for public view
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Abstract
Because of the designable materials properties, compatibility with conventional Si fabrication and thin film processes, and unique physical and chemical properties, PS is a versatile material with potential in a number of different application areas. Optical and optoelectronic applications are based on the tunable optical properties of the porous layer, such as the index of refraction and layer thickness (solar cells, PDs, reflectors), and on the various luminescence phenomena linked to PS (LEDs).
Firstly, Fabrication of PS layers (PSLs) was performed by photoelectrochemical etching (PECE) process on the front side of textured n+ p Si junctions. The formed porosity was determined gravimetrically within a good range of 72 - 80%. The effect of porosity on the structure, electrical, and photoelectrical properties was investigated. Surface morphology and the crystallites size of PS were characterized by using scanning electron microscope (SEM). Scanning electron microscope (SEM) shows the evolution of PSLs morphology through the increase in surface area and roughness due to the regular increase in porosity.
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Secondly, The 100 nm-thick SiO2 film was deposited on the PS layer fabricated at (10 min) by RF sputtering with a power of 200W at ambient temperature.
The optical properties of the fabricated PSLs and SiO2/PS layer have been characterized by using a UV–Vis spectrophotometer equipped with an integrating sphere attachment. The reflection measurements showed a good light trapping at wavelengths ranging from 300 to 1000 nm at 10 min etching time but the double layer SiO2/PS showed excellent light trapping and the lowest reflection. The optical absorption coefficient was calculated from the reflection spectra and the optical band gap was determined. The optical band gaps have been found to tunable with the variation of particle size, which attributed to quantum confinement effect. from the photoluminescence (PL) measurements, the PL peak intensity increases upon increasing the porosity and also shows slight blue shifts from 656 nm to 641 nm as the porosity increases. The band gaps of PSLs obtained from the photoluminescence measurements and from the reflection data were compared. It is found that the band gap increases from 1.86 eV to 1.97 eV for fabricated PSLs at 5 min
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and 10 min, respectively and reach 2.49 eV for SiO2/PS layer, which is higher than the band gap of silicon (1.12 eV).
The current-voltage (I-V) characteristics of Al/ PS /n+ p/Al and Al/SiO2/PS /n+ p/Al junction were investigated and compared with the reference Al/n+ p/Al junction.
Under illumination, the short-circuit current density (JSC) increased from 0.53 mA/cm2 and 1.83 mA/cm2 to 2.04 mA/cm2. And the open-circuit voltage (VOC) increased from 0.227 V and 0.465 V to 0.509V.
The photosensitivity of SiO2/PS solar cells showed a noticeable enhancement in quantum efficiency of the PS cells by increasing passivation effect.
In this thesis, all the structural, optical and electrical properties of the treated textured cells were investigated and compared with the untreated textured cell under the variation of etching time and the effect of deposition silicon dioxide layer on PS layer. The results confirm that SiO2/PS layer formed on textured surface can be used as both broadband antireflection coatings and excellent passivation layers for the application in solar cells.