The Experts below are selected from a list of 2214 Experts worldwide ranked by ideXlab platform
R Alcubilla - One of the best experts on this subject based on the ideXlab platform.
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crystalline silicon surface passivation with amorphous sicx h films deposited by plasma enhanced chemical vapor deposition
Journal of Applied Physics, 2005Co-Authors: I Marti, Cristobal Voz, A Orpella, J Puigdollers, M Vette, M Gari, R AlcubillaAbstract:Surface-passivating properties of hydrogenated amorphous silicon carbide films (a-SiCx:H) deposited by plasma-enhanced chemical-vapor deposition on both p- and n-type crystalline silicon (c-Si) have been extensively studied by our research group in previous publications. We characterized surface recombination by measuring the dependence of the effective lifetime (τeff) on Excess Carrier Density (Δn) through quasi-steady-state photoconductance technique. Additionally, we fitted the measured τeff(Δn) curves applying an insulator/semiconductor model which allows us to determine the surface recombination parameters. In this paper, this model is analyzed in detail focusing on the accuracy in the determination of the fitting parameters and revealing uncertainties not detected up to now. Taking advantage of this analysis, the dependence of surface passivation on film deposition conditions is revised including intrinsic a-SiCx:H films on both p- and n-type c-Si and phosphorus-doped a-SiCx:H films on p-type c-Si. ...
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surface passivation of p type crystalline si by plasma enhanced chemical vapor deposited amorphous sic x h films
Applied Physics Letters, 2001Co-Authors: I Martin, Andres Cuevas, M Vetter, A Orpella, J Puigdollers, R AlcubillaAbstract:Excellent passivation properties of intrinsic amorphous silicon carbide (a-SiCx:H) films deposited by plasma enhanced chemical vapor deposition on single-crystalline silicon (c-Si) wafers have been obtained. The dependence of the effective surface recombination velocity, Seff, on deposition temperature, total pressure and methane (CH4) to silane (SiH4) ratio has been studied for these films using lifetime measurements made with the quasi-steady-state photoconductance technique. The dependence of the effective lifetime, teff, on the Excess Carrier Density, ?n, has been measured and also simulated through a physical model based on Shockley–Read–Hall statistics and an insulator/semiconductor structure with fixed charges and band bending. A Seff at the a-SiCx:H/c-Si interface lower than 30?cm?s-1 was achieved with optimized deposition conditions. This passivation quality was found to be three times better than that of noncarbonated amorphous silicon (a-Si:H) films deposited under equivalent conditions.
Andres Cuevas - One of the best experts on this subject based on the ideXlab platform.
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influence of net doping Excess Carrier Density and annealing on the boron oxygen related defect Density in compensated n type silicon
Journal of Applied Physics, 2011Co-Authors: Fiacre E Rougieux, Daniel Macdonald, Bianca Lim, Jean M Schmidt, Maxime Forster, Andres CuevasAbstract:In this study, we present experimental data regarding the concentration of the boron-oxygen complex in compensated n-type silicon when subjected to illumination. We find that the defect Density is independent of the net dopant concentration and is strongly dependent on the minority Carrier concentration during illumination. We show that annealing at temperatures in the range 500 � C to 700 � C permanently reduces the defect Density possibly via a decrease in the oxygen dimer concentration. V C 2011 American Institute of Physics. [doi:10.1063/1.3633492]
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surface passivation of p type crystalline si by plasma enhanced chemical vapor deposited amorphous sic x h films
Applied Physics Letters, 2001Co-Authors: I Martin, Andres Cuevas, M Vetter, A Orpella, J Puigdollers, R AlcubillaAbstract:Excellent passivation properties of intrinsic amorphous silicon carbide (a-SiCx:H) films deposited by plasma enhanced chemical vapor deposition on single-crystalline silicon (c-Si) wafers have been obtained. The dependence of the effective surface recombination velocity, Seff, on deposition temperature, total pressure and methane (CH4) to silane (SiH4) ratio has been studied for these films using lifetime measurements made with the quasi-steady-state photoconductance technique. The dependence of the effective lifetime, teff, on the Excess Carrier Density, ?n, has been measured and also simulated through a physical model based on Shockley–Read–Hall statistics and an insulator/semiconductor structure with fixed charges and band bending. A Seff at the a-SiCx:H/c-Si interface lower than 30?cm?s-1 was achieved with optimized deposition conditions. This passivation quality was found to be three times better than that of noncarbonated amorphous silicon (a-Si:H) films deposited under equivalent conditions.
Kestutis Jarasiūnas - One of the best experts on this subject based on the ideXlab platform.
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excitation dependent Carrier lifetime and diffusion length in bulk cdte determined by time resolved optical pump probe techniques
Journal of Applied Physics, 2018Co-Authors: Patrik Ščajev, S Miasojedovas, A Mekys, Darius Kuciauskas, K G Lynn, Santosh K Swain, Kestutis JarasiūnasAbstract:We applied time-resolved pump-probe spectroscopy based on free Carrier absorption and light diffraction on a transient grating for direct measurements of the Carrier lifetime and diffusion coefficient D in high-resistivity single crystal CdTe (codoped with In and Er). The bulk Carrier lifetime τ decreased from 670 ± 50 ns to 60 ± 10 ns with increase of Excess Carrier Density N from 1016 to 5 × 1018 cm−3 due to the excitation-dependent radiative recombination rate. In this N range, the Carrier diffusion length dropped from 14 μm to 6 μm due to lifetime decrease. Modeling of in-depth (axial) and in-plane (lateral) Carrier diffusion provided the value of surface recombination velocity S = 6 × 105 cm/s for the untreated surface. At even higher excitations, in the 1019–3 × 1020 cm−3 Density range, D increase from 5 to 20 cm2/s due to Carrier degeneracy was observed.
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Carrier dynamics in bulk gan
Journal of Applied Physics, 2012Co-Authors: Patrik Scˇajev, Kestutis Jarasiūnas, S Okur, U Ozgur, H MorkocAbstract:Carrier dynamics in hydride vapor phase epitaxy grown bulk GaN with very low Density of dislocations, 5–8 × 105 cm−2, have been investigated by time-resolved photoluminescence (PL), free Carrier absorption, and light-induced transient grating techniques in the Carrier Density range of 1015 to ∼1019 cm−3 under single and two photon excitation. For two-photon Carrier injection to the bulk (527 nm excitation), diffusivity dependence on the Excess Carrier Density revealed a transfer from minority to ambipolar Carrier transport with the ambipolar diffusion coefficient Da saturating at 1.6 cm2/s at room temperature. An extremely long lifetime value of 40 ns, corresponding to an ambipolar diffusion length of 2.5 μm, was measured at 300 K. A nearly linear increase of Carrier lifetime with temperature in the 80–800 K range and gradual decrease of D pointed out a prevailing mechanism of diffusion-governed nonradiative recombination due to Carrier diffusive flow to plausibly the grain boundaries. Under single photon...
Rolf Brendel - One of the best experts on this subject based on the ideXlab platform.
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interpretation of recombination at c si sinx interfaces by surface damage
Journal of Applied Physics, 2010Co-Authors: S Steingrube, Jan Schmidt, Pietro P. Altermatt, Daniel S Steingrube, Rolf BrendelAbstract:The measured effective surface recombination velocity Seff at the interface between crystalline p-type silicon (p-Si) and amorphous silicon nitride (SiNx) layers increases with decreasing Excess Carrier Density Δn<1015 cm−3 at dopant densities below 1017 cm−3. If such an interface is incorporated into Si solar cells, it causes their performance to deteriorate under low-injection conditions. With the present knowledge, this effect can neither be experimentally avoided nor fully understood. In this paper, Seff is theoretically reproduced in both p-type and n-type Si at all relevant Δn and all relevant dopant densities. The model incorporates a reduction in the Shockley–Read–Hall lifetime in the Si bulk near the interface, called the surface damage region (SDR). All of the parameters of the model are physically meaningful, and a parametrization is given for numerical device modeling. The model predicts that a ten-fold reduction in the Density of defect states within the SDR is sufficient to weaken this undes...
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Camera-Based Photoluminescence Lifetime Imaging of Crystalline Silicon Wafers
2009Co-Authors: Rolf Brendel, Karsten Bothe, David Hinken, Jan Schmidt, Sandra HerlufsenAbstract:Photoconductance-calibrated photoluminescence lifetime imaging (PC-PLI) is a fast and easy-to-apply method for spatially resolved Carrier lifetime measurements of crystalline silicon wafers. The photoluminescence signal in arbitrary units is converted into absolute values of the actual Carrier lifetime by measurements of the photoconductance of the silicon wafer. We determined a calibration function which is valid for wafers of arbitrary dopant densities by utilizing a fundamental relationship between photoluminescence and dopant Density. In principle, a single measurement of the relation between photoluminescence signal and Excess Carrier Density is sufficient to obtain this calibration function due to its dependence on the dopant Density. We demonstrate that PC-PLI allows high resolution lifetime measurements down to injection levels of 10 cm and is in agreement with light-biased microwave-detected photoconductance decay (MW-PCD) lifetime mappings.
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Photoconductance‐calibrated photoluminescence lifetime imaging of crystalline silicon
physica status solidi (RRL) - Rapid Research Letters, 2008Co-Authors: Sandra Herlufsen, David Hinken, Karsten Bothe, Jan Schmidt, Rolf BrendelAbstract:We use photoluminescence (PL) measurements by a silicon charge-coupled device camera to generate high-resolution lifetime images of multicrystalline silicon wafers. Absolute values of the Excess Carrier Density are determined by calibrating the PL image by means of contactless photoconductance measurements. The photoconductance setup is integrated in the camera-based PL setup and therefore identical measurement conditions are realised. We demonstrate the validity of this method by comparison with microwave-detected photoconductance decay measurements. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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Defect imaging in multicrystalline silicon using a lock-in infrared camera technique
Journal of Applied Physics, 2007Co-Authors: Peter Pohl, Jan Schmidt, Christian Schmiga, Rolf BrendelAbstract:We image the lifetime distribution of multicrystalline silicon wafers by means of calibrated measurements of the free-Carrier emission using an infrared camera. The spatially resolved lifetime measurements are performed as a function of the light-generated Excess Carrier Density, showing a pronounced increase in lifetime with decreasing injection Density at very low injection levels. Two theoretical models are applied to describe the abnormal lifetime increase: (i) minority-Carrier trapping and (ii) depletion region modulation around charged bulk defects. The trapping model is found to give better agreement with the experimental data. By fitting the trapping model to each point of the lifetime image recorded at different injection levels, we generate a trap Density mapping. On multicrystalline silicon wafers we find a clear correlation between trap and dislocation Density mappings.
Daniel Macdonald - One of the best experts on this subject based on the ideXlab platform.
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influence of net doping Excess Carrier Density and annealing on the boron oxygen related defect Density in compensated n type silicon
Journal of Applied Physics, 2011Co-Authors: Fiacre E Rougieux, Daniel Macdonald, Bianca Lim, Jean M Schmidt, Maxime Forster, Andres CuevasAbstract:In this study, we present experimental data regarding the concentration of the boron-oxygen complex in compensated n-type silicon when subjected to illumination. We find that the defect Density is independent of the net dopant concentration and is strongly dependent on the minority Carrier concentration during illumination. We show that annealing at temperatures in the range 500 � C to 700 � C permanently reduces the defect Density possibly via a decrease in the oxygen dimer concentration. V C 2011 American Institute of Physics. [doi:10.1063/1.3633492]
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doping dependence of the Carrier lifetime crossover point upon dissociation of iron boron pairs in crystalline silicon
Applied Physics Letters, 2006Co-Authors: Daniel Macdonald, Thorsten Trupke, Thomas Roth, P N K Deenapanray, R A BardosAbstract:The Excess Carrier Density at which the Carrier lifetime in crystalline silicon remains unchanged after dissociating iron-boron pairs, known as the crossover point, is reported as a function of the boron dopant concentration. Modeling this doping dependence with the Shockley-Read-Hall model does not require knowledge of the iron concentration and suggests a possible refinement of reported values of the capture cross sections for electrons and holes of the acceptor level of iron-boron pairs. In addition, photoluminescence-based measurements were found to offer some distinct advantages over traditional photoconductance-based techniques in determining recombination parameters from low-injection Carrier lifetimes.
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Minority Carrier lifetime in plasma-textured silicon wafers for solar cells
Solar Energy Materials and Solar Cells, 2005Co-Authors: G. Kumaravelu, Daniel Macdonald, Maan M. Alkaisi, J. Zhao, B Rong, A BittarAbstract:In this work a comparison between plasma induced defects by two different SF6 etching techniques, Reactive Ion Etching (RIE) and High Density Plasma (HDP), is presented. It is found that without any Defect Remove Etching (DRE), the minority Carrier lifetime is the highest for the HDP technique. After DRE, the minority Carrier lifetime rises as high as 750 μs for both RIE and HDP textured wafers at an Excess Carrier Density of 1x10 15 cm -3 . The measured lifetimes correspond to an implied one-sun opencircuit voltage of around 680mV compared to about 640mV before DRE for the HDP textured wafers. We also noted that in the RIE process the induced defect Density was significantly lower for wafers etched at 300 K than those etched at 173 K.
