Search results for " silicon"
showing 10 items of 247 documents
Sub-gap defect density characterization of molybdenum oxide: An annealing study for solar cell applications
2020
AbstractThe application of molybdenum oxide in the photovoltaic field is gaining traction as this material can be deployed in doping-free heterojunction solar cells in the role of hole selective contact. For modeling-based optimization of such contact, knowledge of the molybdenum oxide defect density of states (DOS) is crucial. In this paper, we report a method to extract the defect density through nondestructive optical measures, including the contribution given by small polaron optical transitions. The presence of defects related to oxygen-vacancy and of polaron is supported by the results of our opto-electrical characterizations along with the evaluation of previous observations. As part…
Growth of polyaniline films on porous silicon layers
1993
Abstract The electrochemical deposition of electrically active polyaniline films (PANI) onto the surface of porous silicon (PS) layers formed at p- and n-type silicon wafers has been studied using cyclic voltammetry measurements and infrared spectroscopy. The process of PANI deposition is easier on the PS layers formed at n-Si wafers and essentially retarded at PS/p-Si samples, presumably due to a parallel reaction of oxygen evolution. The polymerization reaction starts at the pore bottoms and propagates towards the external surface of the PS layer. Electric conduction of PS/PANI composites is lower than of uncovered PS layers.
Strain effects and phonon-plasmon coupled modes in Si-doped AlN
2009
The E 2h and A 1 (LO) phonon modes of AlN films grown on sapphire are analyzed by Raman scattering as a function of silicon doping for concentrations covering from 5.5 x 10 19 cm ―3 to 5.2 x 10 21 cm ―3 . For high doping levels the appearance of a mode around 520 cm ―1 indicates the precipitation of crystalline silicon in the samples and its inhomogeneous incorporation to the AlN layer. The frequency of this mode shifts to lower energies with doping, indicating that the silicon crystals are embedded in the AlN lattice and under tensile strain. On the other hand, the AlN phonon modes are blue-shifted due to the compressive strain as a result of the silicon incorporation. This strain is parti…
Capacitance study of thin film SnO2:F/p-type a-Si:H heterojunctions
2011
Abstract We characterized SnO 2 :F/p-type a-Si:H heterojunctions by current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature to determine the junction parameters. Samples with circular geometry and different diameters were characterized. The current scales with the junction area, and the current density J as a function of the voltage V is a slightly asymmetric curve with a super-linear behaviour (cubic law) for high voltages. Using a transmission line model valid for devices with circular geometry, we studied the effects of the SnO 2 :F resistivity on the measured capacitance when the SnO2:F layer works as an electrical contact. The measured C-V curve allows us t…
Particle Detectors made of High Resistivity Czochralski Grown Silicon
2004
We describe the fabrication process of fullsize silicon microstrip detectors processed on silicon wafers grown by magnetic Czochralski method. Defect analysis by DLTS spectroscopy as well as minority carrier lifetime measurements by µPCD method are presented. The electrical and detection properties of the Czochralski silicon detectors are comparable to those of leading commercial detector manufacturers. The radiation hardness of the Czochralski silicon detectors was proved to be superior to the devices made of traditional Float Zone silicon material.
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…
Programmable Supercontinuum Laser Spectrum Generator Based on a Liquid-Crystal on Silicon Spatial Light Modulator
2021
Supercontinuum (SC) lasers combine a broadband light spectrum with the unique properties of single-mode lasers. In this work we present an optical system to spectrally filter a SC laser source using liquid-crystal on silicon (LCoS) spatial light modulators (SLM). The proposed optical system disperses the input laser and the spectrally separated components are projected onto the LCoS-SLM, where the state of polarization of each wavelength is separately modulated. Finally, recombining the modulated spectral components results in an output laser source where the spectrum can be controlled dynamically from a computer. The system incorporates two branches to independently control the visible (VI…
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.
The role of impurities in the irradiation induced densification of amorphous SiO(2).
2011
In a recent work (Buscarino et al 2009 Phys. Rev. B 80 094202), by studying the properties of the (29)Si hyperfine structure of the E'(γ) point defect, we have proposed a model able to describe quantitatively the densification process taking place upon electron irradiation in amorphous SiO(2) (a-SiO(2)). In particular, we have shown that it proceeds heterogeneously, through the nucleation of confined densified regions statistically dispersed into the whole volume of the material. In the present experimental investigation, by using a similar approach on a wider set of materials, we explore how this process is influenced by impurities, such as OH and Cl, typically involved in relevant concent…