This paper reports the fabrication of n-type crystalline Si based solar cell using boron liquid solution (BLS) deposited by spray method for p-type emitter formation. The X-ray photoelectron spectroscopy (XPS) was used for the analysis of surface composition and electronic states of elements at the glass layer of dopant (GLD) obtained from BLS. The investigation of the borosilicate glass layer (BSG) created on a base of GLD during diffusion process were carried out by transmission electron microscopy (TEM). The diffusion profiles were determined by secondary ion mass spectrometry (SIMS) and electrochemical capacitance-voltage (EC-V) techniques, whereas the solar cells were characterized by the light current-voltage (I-V) and spectral measurements. The influence of a doping process on a minority carrier lifetime of the Si wafers was detected by quasi-steady-state photoconductance technique. Application of the elaborated BSL allowed to obtain the p-type Si emitters from BSG layer which exhibits unproblematic etching behaviour after diffusion process and final fabrication of the solar cells with the fill factor of 74% and photoconversion efficiency of 13.04 %. The elaborated BLS is a source which offers an attractive practicable alternative to form emitters on the n-type Si substrate.
Amorphous a-SiCxNy:H thin films may be an alternative to a-Si:N:H coatings which are commonly used in silicon solar cells. This material was obtained by PECVD (13.56 MHz) method. The reaction gases used: silane, methane, nitrogen and ammonia. The structure of the layers were investigated by scanning electron microscopy (SEM) and infrared spectroscopy (FTIR). IR absorption spectra of a-SiCxNy:H layers confirmed the presence of various hydrogen bonds – it is important for passivation of Si structural defects. The ellipsometric measurements were implemented to determine the thickness of layers d, refractive index n, extinction coefficient k and energy gap Eg. The values of the energy gap of a-SiCxNy:H layers are in the range from 1.89 to 4.34 eV. The correlation between energy gap of materials and refractive index was found. Generally the introduction of N and/or C into the amorphous silicon network rapidly increases the Eg values.
Electrochromic system is the one of the most popular devices using color memory effect under the influence of an
applied voltage. The electrochromic system was produced based on the thin WO3 electrochromic films. Films were
prepared by RF magnetron sputtering from tungsten targets in a reactive Ar+O2 gas atmosphere of various Ar/O2 ratios.
The technological gas mixture pressure was 3 Pa and process temperature 30°C. Structural and optical properties of WO3
films were investigated for as-deposited and heat treated samples at temperature range from 350°C to 450°C in air. The
material revealed the dependence of properties on preparation conditions and on post-deposition heat treatment. Main
parameters of thin WO3 films: thickness d, refractive index n, extinction coefficient k and energy gap Eg were
determined and optimized for application in electrochromic system. The main components of the system were glass plate
with transparent conducting oxides, electrolyte, and glass plate with transparent conducting oxides and WO3 layer. The
optical properties of the system were investigated when a voltage was applied across it. The electrochromic cell revealed
the controllable transmittance depended on the operation voltage.
Photovoltaic structures of multicrystalline silicon were modified by the deposition of a-Si:C:H thin films. The films have been deposited by Plasma Enhanced Chemical Vapor Deposition at 13.56 MHz in SiH4 +CH4 gaseous mixtures. The structures have been investigated by means of optical and electrical methods. Spectral photosensitivity measurements were done at room temperature in voltage and current modes. The signal was registered in the function of light in the visible and near infrared region from 400 to 1100 nm. Silicon structures covered by a-Si:C:H have higher spectral photosensitivities than uncover ones and the apparent increase in efficiency has been observed.
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