Characterization of porous silicon photovoltaic solar cells
Manar Ahmed Farag Ahmed;
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).
Fabrication of PS layers (PSLs) was performed by electrochemical etching process on the front side of textured n+ p Si junctions. The formed porosity was determined gravimetrically within a good range of 88.27 - 97%. 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) and X-ray diffraction (XRD), respectively. Scanning electron microscope (SEM) shows the evolution of PSLs morphology through the increase in surface area due to the regular increase in porosity. The broadening of the FWHM obtained from the XRD spectra provided the reduction in the crystallite size.
The optical properties of the fabricated PSLs have been characterized by using a UV–Vis spectrophotometer equipped with an integrating sphere attachment. The reflection measurements showed an excellent light trapping at wavelengths ranging from 200 to 1000 nm at 30 mA/cm2 etching current density. The optical absorption coefficient was calculated from the reflection spectra and the optical band gap was determined. The value of the energy gap (Eg) was also determined by applying the Kubelka–Munk (K–M or F(R)) method. 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 at 629 nm and 640 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 in a range between 1.84 eV and 2.23 eV, which is higher than the band gap of silicon (1.12 eV).
Fabrication of PS layers (PSLs) was performed by electrochemical etching process on the front side of textured n+ p Si junctions. The formed porosity was determined gravimetrically within a good range of 88.27 - 97%. 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) and X-ray diffraction (XRD), respectively. Scanning electron microscope (SEM) shows the evolution of PSLs morphology through the increase in surface area due to the regular increase in porosity. The broadening of the FWHM obtained from the XRD spectra provided the reduction in the crystallite size.
The optical properties of the fabricated PSLs have been characterized by using a UV–Vis spectrophotometer equipped with an integrating sphere attachment. The reflection measurements showed an excellent light trapping at wavelengths ranging from 200 to 1000 nm at 30 mA/cm2 etching current density. The optical absorption coefficient was calculated from the reflection spectra and the optical band gap was determined. The value of the energy gap (Eg) was also determined by applying the Kubelka–Munk (K–M or F(R)) method. 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 at 629 nm and 640 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 in a range between 1.84 eV and 2.23 eV, which is higher than the band gap of silicon (1.12 eV).
Other data
| Title | Characterization of porous silicon photovoltaic solar cells | Other Titles | توصيف الخلايا الشمسية الفوتوفولتية ذات السيليكون المسامى | Authors | Manar Ahmed Farag Ahmed | Issue Date | 2016 |
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