Search results for " Silicon"
showing 10 items of 247 documents
Modeling and parameter identification of crystalline silicon photovoltaic devices
2011
In this paper the physical correctness of the standard single-exponential (one-diode) model of crystalline-Si photovoltaic devices is examined. In particular, we focus on the shunt current. I-V curves of in situ illuminated polycrystalline-Si photovoltaic modules are measured, and based on these measurements, we extract the shunt current. There is a certain voltage range in which the shunt current shows an Ohmic-like behavior, but the value of the resistance varies with irradiance and the quality of illumination. In addition, the Ohmic behavior takes place at voltages well below the maximum-power point (MPP). At higher voltages, the shunt current drops to negligible values. We conclude that…
Memory effects in MOS capacitors with silicon rich oxide insulators
2000
ABSTRACTTo 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 wereannealed in N2 ambient at temperatures between 950 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 function of such structures has been investigated in metal-oxidesemiconductor (MOS) capacitors with a SRO film sandwiched be…
Initial light-induced degradation study of multicrystalline modules made from silicon material processed through different manufacturing routes
2012
The paper presents results of initial lightinduced degradation (LID) of multicrystalline silicon photovoltaic (PV) modules made of crystalline silicon from different manufacturing processes. The modules were installed within the Sunbelt, in Hyderabad, India. Current-voltage (I–V) characteristics are measured and infra-red (IR) images of the modules are taken at regular intervals. A relationship of the IV degradation with the IR images is discussed. Results from laboratory LID tests at room temperature are performed parallel to the outdoor degradation of PV modules. It was found that the total LID, measured on the module level, after the initial 40 hours is similar for both materials resulti…
Biosensors, Porous Silicon
2002
Biosensors consist of a biologically active layer that responding to an analyte in solution and a powerful transducer that transforms and amplifies the reaction into a measurable signal. Biosensors can constantly measure the presence, absence, or concentration of specific organic or inorganic substances in short response time and ultimately at low cost. They are used commercially in health care, biotechnological process control, agriculture, veterinary medicine, defense, and environmental pollution monitoring. A common requirement of all of these applications is on-site chemical information—preferably in real time—on some dynamic or rapidly evolving process. Most biosensors are based on mol…
Assessment of a New Analytical Expression for the Maximum-Power Point Voltage with Series Resistance
2021
This work compares a recently developed analytical expression for the maximum-power point voltage with experimental data, to test its usability for crystalline silicon solar cells. The experimental data covers measurements from 18 multicrystalline silicon solar cells with different bulk resistivities and cell architectures. We show that the expression is able to predict the maximum power obtainable by the measured cells with relative discrepancies below 1%. Additionally, we compare the accuracy of this new expression with two already existing models.
Study of silicon crystal surface formation based on molecular dynamics simulation results
2014
Abstract The equilibrium shape of 〈 110 〉 -oriented single crystal silicon nanowire, 8 nm in cross-section, was found from molecular dynamics simulations using LAMMPS molecular dynamics package. The calculated shape agrees well to the shape predicted from experimental observations of nanocavities in silicon crystals. By parametrization of the shape and scaling to a known value of { 111 } surface energy, Wulff form for solid-vapor interface was obtained. The Wulff form for solid–liquid interface was constructed using the same model of the shape as for the solid–vapor interface. The parameters describing solid–liquid interface shape were found using values of surface energies in low-index dir…
Additive Manufacturing of Multi‐Scale Porous Soft Tissue Implants That Encourage Vascularization and Tissue Ingrowth
2021
Medical devices, such as silicone-based prostheses designed for soft tissue implantation, often induce a suboptimal foreign-body response which results in a hardened avascular fibrotic capsule around the device, often leading to patient discomfort or implant failure. Here, it is proposed that additive manufacturing techniques can be used to deposit durable coatings with multiscale porosity on soft tissue implant surfaces to promote optimal tissue integration. Specifically, the “liquid rope coil effect”, is exploited via direct ink writing, to create a controlled macro open-pore architecture, including over highly curved surfaces, while adapting atomizing spray deposition of a silicone ink t…
Role of the Back Metal-Semiconductor Contact on the Performances of a-Si:H Solar Cells
2011
We have investigated the role of the metal-semiconductor back contact on the performances of thin film modules consisting of single junction a-Si:H photovoltaic (PV) cells deposited with p-i-n configuration. We find that an adequate choice of the back contact helps reducing the barrier height of the junction improving the contact conductivity. For this purpose Mo has shown to be effective. Moreover we find that Mo, as refractory material, has additional beneficial effects reducing the formation of defects leading to the decrease of recombination losses. We have then fabricated a PV module on flexible substrate for indoor energy harvesting applications using Mo as back contact. An efficiency…
Carrier transport mechanism in the SnO(2):F/p-type a-Si:H heterojunction
2011
We characterize SnO(2):F/p-type a-Si:H/Mo structures by current-voltage (I-V) and capacitance-voltage (C-V) measurements at different temperatures to determine the transport mechanism in the SnO2:F/p-type a-Si:H heterojunction. The experimental I-V curves of these structures, almost symmetric around the origin, are ohmic for vertical bar V vertical bar< 0:1 V and have a super-linear behavior (power law) for vertical bar V vertical bar < 0:1 V. The structure can be modeled as two diodes back to back connected so that the main current transport mechanisms are due to the reverse current of the diodes. To explain the measured C-V curves, the capacitance of the heterostructure is modeled as the …
Silicon germanium platform enabling mid-infrared to near-infrared conversion for telecom and sensing applications
2014
This paper presents the potential of silicon germanium waveguides in the nonlinear conversion of light from mid-infrared wavelengths to the telecom band utilizing four-wave mixing. Design aspects and first characterization results of fabricated devices are presented.