Search results for "Crystalline Silicon"
showing 10 items of 74 documents
Detection of planar defects caused by ion irradiation in Si using molecular dynamics
2007
We have analyzed the evolution of defects caused by self-irradiation of crystalline silicon. A classical molecular dynamics simulation was followed by defect analysis using the Pixel Mapping (PM) method. The PM identified {311} planar defects and long-chain structures of the so-called interstitial chains following low energy (1 keV) ion impact. The areal density obtained from simulation of self-interstitial atoms was about two thirds of that of experiments reported in the literature [Jpn. J. Appl. Phys. 30 (1991) L639], while the atomic configuration on respective planes agreed exactly.
Hydrodynamical aspects of the floating zone silicon crystal growth process
2014
Abstract 3D numerical modeling of dopant transport in the melt is carried out for the 100 mm floating zone silicon single crystal growth process. The axis-symmetric shape of the molten zone is calculated with the program FZone considering the coil and the high frequency (HF) electromagnetic (EM) field in 3D. Time dependent melt flow, temperature and dopant concentration fields are modeled using a specialized solver based on the open source code library OpenFOAM ® . The influence of the Marangoni coefficient in the boundary conditions on the melt velocity field is analyzed. The obtained shapes of the crystallization interface and resistivity profiles in the grown crystal are compared with ex…
Modeling and parameter identification of crystalline silicon photovoltaic devices
2011
This paper tests the standard single-exponential model of the electrical characteristics of crystalline-Si photovoltaic devices, focusing on the (apparent) shunt current. Measured characteristics of illuminated polycrystalline-Si photovoltaic modules are modeled, and the apparent shunt current is analyzed. It is shown that an Ohmic-like behavior only takes place at voltages well below the maximum-power point. At higher voltages, the apparent shunt current quickly drops to negligible values. Modeling a crystalline-Si PV device with a fixed shunt resistance may therefore lead to underestimation of the maximum power exceeding 10% at certain irradiance levels.
Enhancement of photoconversion efficiency in dye-sensitized solar cells exploiting pulsed laser deposited niobium pentoxide blocking layers
2015
Abstract Among all the photovoltaic technologies developed so far, dye-sensitized solar cells are considered as a promising alternative to the expensive and environmentally unfriendly crystalline silicon-based solar cells. One of the possible strategies employed to increase their photovoltaic efficiency is to reduce the charge recombination at the cell conductive substrate through the use of a compact blocking layer. In this paper, we report on the fabrication and characterization of dye-sensitized solar cells employing niobium pentoxide (Nb 2 O 5 ) thin film blocking layer deposited through the pulsed laser deposition technique on conductive substrates. The careful selection of the optimal…
Small Particles and Thin Films of Metals on Ceramic Oxides
1989
This paper is aimed at presenting some recent ideas and experimental results on characterization and properties of small particles and thin films of metals on oxide surfaces. Analysis is restricted to metallic films on well-defined surfaces, mainly monocrystalline surfaces and to ceramic oxides having a marked ionic character. The properties of metallic films obtained by chemical reduction of oxides and those of deposits are compared. Nucleation and growth modes are described. Interfacial properties are analysed in terms of size or thickness effect and in the general framework of the ceramic-metal bonding.
HCl gas gettering for crystalline silicon thin film solar cells
2011
Crystalline silicon thin film (cSiTF) solar cells could be an attractive alternative for standard silicon solar cells. Only a small amount of the expensive high purity silicon is needed for the epitaxial deposition on a low-cost silicon substrate made from e.g. metallurgical grade (MG) or upgraded metallurgical grade (UMG) silicon. The resulting product is called epitaxial wafer equivalent (EpiWE) because it can be processed in a standard wafer cell production. MG-Si and UMG-Si still contain a huge amount of metallic impurities. These impurities have to be removed by gettering methods in order to prevent diffusion into the highly pure active silicon layer during the high-temperature deposit…
Photoluminescence Imaging and LBIC Characterization of Defects in mc-Si Solar Cells
2018
Today’s photovoltaic market is dominated by multicrystalline silicon (mc-Si) based solar cells with around 70% of worldwide production. In order to improve the quality of the Si material, a proper characterization of the electrical activity in mc-Si solar cells is essential. A full-wafer characterization technique such as photoluminescence imaging (PLi) provides a fast inspection of the wafer defects, though at the expense of the spatial resolution. On the other hand, a study of the defects at a microscopic scale can be achieved through the light-beam induced current technique. The combination of these macroscopic and microscopic resolution techniques allows a detailed study of the electric…
Broadband light trapping in thin film solar cells with self-organized plasmonic nano-colloids
2015
The intense light scattered from metal nanoparticles sustaining surface plasmons makes them attractive for light trapping in photovoltaic applications. However, a strong resonant response from nanoparticle ensembles can only be obtained if the particles have monodisperse physical properties. Presently, the chemical synthesis of colloidal nanoparticles is the method that produces the highest monodispersion in geometry and material quality, with the added benefits of being low-temperature, low-cost, easily scalable and of allowing control of the surface coverage of the deposited particles. In this paper, novel plasmonic back-reflector structures were developed using spherical gold colloids wi…
Memory effects in MOS capacitors with silicon quantum dots
2001
To form crystalline Si dots embedded in SiO2, we have deposited thin films of silicon-rich oxide (SRO) by plasma-enhanced chemical vapor deposition of SiH4 and O2. Then the materials have been annealed in N2 ambient at temperatures between 950°C and 1100°C. Under such processing, the supersaturation of Si in the amorphous SRO film produces the formation of crystalline Si dots embedded in SiO2. The narrow dot size distributions, analyzed by transmission electron microscopy, are characterized by average grain radii and standard deviations down to about 1 nm. The memory functions of such structures has been investigated in MOS capacitors with a SRO film sandwiched between two thin SiO2 layers …
Numerical study of transient behaviour of molten zone during industrial FZ process for large silicon crystal growth
2004
The fully transient axisymmetric model has been developed for calculation of phase boundaries in large (up to 200 mm diameter) industrial floating zone (FZ) silicon single crystal growth with the needle-eye technique. The transient model is implemented in a specialized computer program. The model and program are based on a previously developed model and program for steady-state FZ process calculations. This transient approach allows studying of such substantially time-dependent process phases as the growth of the starting and ending cones of the crystal rod, which are particularly important for growth of large crystals in practice. Numerous calculations are carried out and the results for r…