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Effects Of Cu Diffusion From Zntecu Ti Contacts On Carrier Lifetime Of Cds Cdte Thin Film Solar Cells
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Book Synopsis Effects of Cu Diffusion from ZnTe by :
Download or read book Effects of Cu Diffusion from ZnTe written by and published by . This book was released on 2008 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the performance of CdS/CdTe thin film PV devices processed with a ZnTe:Cu/Ti contact to investigate how carrier lifetime in the CdTe layer is affected by Cu diffusion from the contact.
Book Synopsis Effects of Cu Diffusion From ZnTe by :
Download or read book Effects of Cu Diffusion From ZnTe written by and published by . This book was released on 2008 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advanced Concepts in Photovoltaics by : Arthur J. Nozik
Download or read book Advanced Concepts in Photovoltaics written by Arthur J. Nozik and published by Royal Society of Chemistry. This book was released on 2014-07-10 with total page 631 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photovoltaic systems enable the sun’s energy to be converted directly into electricity using semiconductor solar cells. The ultimate goal of photovoltaic research and development is to reduce the cost of solar power to reach or even become lower than the cost of electricity generated from fossil and nuclear fuels. The power conversion efficiency and the cost per unit area of the phototvoltaic system are critical factors that determine the cost of photovoltaic electricity. Until recently, the power conversion efficiency of single-junction photovoltaic cells has been limited to approximately 33% - the so-called Shockley-Queisser limit. This book presents the latest developments in photovoltaics which seek to either reach or surpass the Shockley-Queisser limit, and to lower the cell cost per unit area. Progress toward this ultimate goal is presented for the three generations of photovoltaic cells: the 1st generation based on crystalline silicon semiconductors; the 2nd generation based on thin film silicon, compound semiconductors, amorphous silicon, and various mesoscopic structures; and the 3rd generation based on the unique properties of nanoscale materials, new inorganic and organic photoconversion materials, highly efficient multi-junction cells with low cost solar concentration, and novel photovoltaic processes. The extent to which photovoltaic materials and processes can meet the expectations of efficient and cost effective solar energy conversion to electricity is discussed. Written by an international team of expert contributors, and with researchers in academia, national research laboratories, and industry in mind, this book is a comprehensive guide to recent progress in photovoltaics and essential for any library or laboratory in the field.
Book Synopsis Analysis of Cu Difusion in ZnTe-Based Contacts for Thin-Film CdS/CdTe Solar Cells by :
Download or read book Analysis of Cu Difusion in ZnTe-Based Contacts for Thin-Film CdS/CdTe Solar Cells written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ohmic contacts to thin-film CdS/CdTe photovoltaic devices have been formed using a two-layer contact interface of undoped ZnTe (ZnTe) and Cu-doped ZnTe (ZnTe:Cu), followed by Ni or Ti as an outer metallization. Secondary ion mass spectroscopy (SIMS) is used to study Cu diffusion within this back-contact structure, and also, to monitor Cu diffusion from the contact into the CdTe. When Nimetallization is used, the ZnTe:Cu layer becomes increasingly depleted of Cu, and Ni diffusion into the ZnTe:Cu increases as the contact deposition temperature increases from 100 deg. C to 300 deg. C. Cu depletion is not observed when Ni is replaced with Ti. Diffusion of Cu from the ZnTe:Cu layer into the ZnTe layer also increases with contact deposition temperature, and produces a buildup of Cuat the ZnTe/CdTe interface. High-mass resolution SIMS indicates that, although Cu levels in the CdTe remain low, Cu diffusion from the contact proceeds into the CdTe layer and toward the CdTe/CdS junction region.
Book Synopsis Evolution of CdS/CdTe Device Performance During Cu Diffusion by :
Download or read book Evolution of CdS/CdTe Device Performance During Cu Diffusion written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analysis of Cu Diffusion in ZnTe-Based Contacts for Thin-Film CdS by :
Download or read book Analysis of Cu Diffusion in ZnTe-Based Contacts for Thin-Film CdS written by and published by . This book was released on 1998 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ohmic contacts to thin-film CdS/CdTe photovoltaic devices have been formed using a two-layer contact interface of undoped ZnTe (ZnTe) and Cu-doped ZnTe (ZnTe:Cu), followed by Ni or Ti as an outer metallization. Secondary ion mass spectroscopy (SIMS) is used to study Cu diffusion within this back-contact structure, and also, to monitor Cu diffusion from the contact into the CdTe. When Ni metallization is used, the ZnTe:Cu layer becomes increasingly depleted of Cu, and Ni diffusion into the ZnTe:Cu increases as the contact deposition temperature increases from 100 C to 300 C. Cu depletion is not observed when Ni is replaced with Ti. Diffusion of Cu from the ZnTe:Cu layer into the ZnTe layer also increases with contact deposition temperature, and produces a buildup of Cu at the ZnTe/CdTe interface. High-mass resolution SIMS indicates that, although Cu levels in the CdTe remain low, Cu diffusion from the contact proceeds into the CdTe layer and toward the CdTe/CdS junction region.
Book Synopsis Electrical Characterization of Cu Composition Effects in CdS/CdTe Thin-Film Solar Cells with a ZnTe:Cu Back Contact: Preprint by :
Download or read book Electrical Characterization of Cu Composition Effects in CdS/CdTe Thin-Film Solar Cells with a ZnTe:Cu Back Contact: Preprint written by and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the effects of Cu composition on the CdTe/ZnTe:Cu back contact and the bulk CdTe. For the back contact, its potential barrier decreases with Cu concentration while its saturation current density increases. For the bulk CdTe, the hole density increases with Cu concentration. We identify a Cu-related deep level at0.55 eV whose concentration is significant when the Cu concentration ishigh. The device performance, which initially increases with Cu concentration then decreases, reflects the interplay between the positive influences and negative influences (increasing deep levels in CdTe) of Cu.
Book Synopsis Analysis of the ZnTe by : M. J. Romero
Download or read book Analysis of the ZnTe written by M. J. Romero and published by . This book was released on 2003 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on the recent use of cathodoluminescence (CL) to probe the depth-dependent changes in radiative recombination that occur in CdTe devices during ZnTe:Cu contacting procedures. These types of CL measurements may be useful to assist in linking impurity diffusion (e.g., Cu) from the contact with depth-dependent variation in electrical activation within the CdTe layer. Variable-energy CL suggests that diffusion from the ZnTe:Cu contact interface may assist in reducing donors levels in the CdTe bulk, and thereby yield p-type material in the region near the contact. CL analysis near abrupt metal discontinuities provides estimates of diffusion lengths for carriers associated with both excitonic and donor-to-acceptor pair recombination. Finally, CL measurements at increasing excitation levels (i.e., increasing electron-beam current) provides estimates of the defect state density, as well as providing evidence that discrete multiple defect bands may exist in CdTe prior to contacting.
Book Synopsis Electrical Characterization of Thin Film CdTe Solar Cells by : Darshini Desai
Download or read book Electrical Characterization of Thin Film CdTe Solar Cells written by Darshini Desai and published by . This book was released on 2007 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photovoltaic device modeling results obtained using AMPS (Analysis of microelectronic and photonic structures) suggest that the dominant recombination mechanism is the SRH recombination through midgap states.
Book Synopsis Spectroscopic Cathodoluminescence Studies of the ZnTe:Cu Contact Process for CdS/CdTe Solar Cells: Preprint by :
Download or read book Spectroscopic Cathodoluminescence Studies of the ZnTe:Cu Contact Process for CdS/CdTe Solar Cells: Preprint written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This conference paper describes the spectroscopic cathodoluminescence (CL), electron-beam induced current (EBIC), and capacitance-Voltage (C-V) measurements are used to study the formation of CdS/CdTe devices processed using ion-beam milling and a ZnTe:Cu/Ti contact. Results show heating in vacuum at~360 deg C and ion-beam milling lead to observable changes in the CL emission from the CdCl2-treatedCdTe surface. Changes in the CL spectrum are also observed as ZnTe:Cu layer thickness increases. These changes are correlated to published studies of defect levels and shown to be due, possibly, to an n-type region existing between the ZnTe:Cu contact interface and the p-CdTe layers. This n-type region is eliminated once a sufficiently thick ZnTe:Cu layer is produced.
Book Synopsis Impurity and Back Contact Effects on CdTe/CdS Thin Film Solar Cells by : Hehong Zhao
Download or read book Impurity and Back Contact Effects on CdTe/CdS Thin Film Solar Cells written by Hehong Zhao and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: CdTe/CdS thin film solar cells are the most promising cost-effective solar cells. The goal of this project is to improve the performance for CdS/CdTe devices by improving the open circuit voltage V[subscript]oc and current density J[subscript]sc. Efforts focused on increasing the V[subscript]oc, which include increasing the doping concentration by introducing Phosphorus and Antimony, finding and testing new back contact materials, and varying the ambient of CSS CdTe. In addition, the effect of Zn2SnO4 on the cells' performance was also studied. Electrical characterization of the thin films and completed devices were carried out by Current-Voltage (J-V), Capacitance-Voltage (C-V), and Spectral Response (SR) measurements. Structural/chemical characterization was done by SEM, XRD and EDS analysis. The ambient of CSS CdTe affects the growth rate, the grain size and electronic properties of CdTe. The N2/O2 mixture with varied ratio (N2/O2=9/1, 7/3, 5/5 and 1/9) was used in this study. The cells' performance and the net carrier concentration were studied as a function of the N2/O2 ratio. The net carrier concentration increases with the increasing O2 concentration. The extrinsic impurities (P and Sb) were incorporated into CdTe layer. Phosphorus was directly introduced into CSS CdTe source. The Sb was incorporated into CdTe by a diffusion process. The effects of the annealing parameters, the excess Sb on CdTe surface, the CdCl2 treatment and the depth of Sb in CdTe were studied. Higher doping concentration up to 1016 cm−3 has been achieved, however, V[subscript]oc is still in the range of 830 mV.
Book Synopsis Electrical Characterization of Cu Composition Effects in CdS/CdTe Thin-Film Solar Cells with a ZnTe by :
Download or read book Electrical Characterization of Cu Composition Effects in CdS/CdTe Thin-Film Solar Cells with a ZnTe written by and published by . This book was released on 2012 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the effects of Cu composition on the CdTe/ZnTe:Cu back contact and the bulk CdTe. For the back contact, its potential barrier decreases with Cu concentration while its saturation current density increases. For the bulk CdTe, the hole density increases with Cu concentration. We identify a Cu-related deep level at ≈0.55 eV whose concentration is significant when the Cu concentration is high. The device performance, which initially increases with Cu concentration then decreases, reflects the interplay between the positive influences and negative influences (increasing deep levels in CdTe) of Cu.
Book Synopsis Formation of ZnTe:Cu/Ti Contacts at High Temperature for CdS/CdTe Devices by :
Download or read book Formation of ZnTe:Cu/Ti Contacts at High Temperature for CdS/CdTe Devices written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Formation of ZnTe written by M. R. Young and published by . This book was released on 2006 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The conclusions of this report are that Cu diffusion from a ZnTe:Cu contact causes good and bad things. The good (Cu in CdS low 10{sup 18} cm{sup -3})--increase in CdTe N{sub A}-N{sub D} that leads to V{sub oc} and FF improvement. The bad (Cu in CdS low 10{sup 18} cm{sup -3})--(1) possibly decreased of shunt resistance ; (2) depletion width in CdTe can become too narrow for optimum current collection at J{sub MPP}; (3) donor reduction in CdS (significant FF loss in LIV); and (4) excessive Cu diffusion into CdS readily observed by red-light bias QE.
Book Synopsis Spectroscopic Cathodoluminescence Studies of the ZnTe by :
Download or read book Spectroscopic Cathodoluminescence Studies of the ZnTe written by and published by . This book was released on 2002 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: This conference paper describes the spectroscopic cathodoluminescence (CL), electron-beam induced current (EBIC), and capacitance-Voltage (C-V) measurements are used to study the formation of CdS/CdTe devices processed using ion-beam milling and a ZnTe:Cu/Ti contact. Results show heating in vacuum at (almost equal to)360 C and ion-beam milling lead to observable changes in the CL emission from the CdCl2-treated CdTe surface. Changes in the CL spectrum are also observed as ZnTe:Cu layer thickness increases. These changes are correlated to published studies of defect levels and shown to be due, possibly, to an n-type region existing between the ZnTe:Cu contact interface and the p-CdTe layers. This n-type region is eliminated once a sufficiently thick ZnTe:Cu layer is produced.
Book Synopsis Analysis of the ZnTe:CU Contact on CdS/CdTe Solar Cells by :
Download or read book Analysis of the ZnTe:CU Contact on CdS/CdTe Solar Cells written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Study of Deep Level Defects of N+-CdS/P-CdTe Solar Cells by : Poonam Rani Kharangarh
Download or read book Study of Deep Level Defects of N+-CdS/P-CdTe Solar Cells written by Poonam Rani Kharangarh and published by . This book was released on 2013 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: Among various photovoltaic materials, polycrystalline cadmium telluride thin film is now the most promising material, due to its low production cost excellent stability and reliability. Current-voltage and capacitance-voltage measurements of CdTe photovoltaic devices at different temperatures can provide valuable information about non-idealities in the n-p semiconductor junction. There are certain limitations which limit the efficiency of CdTe solar cells. There is no real distinction between defects and impurities in CdTe solar cells as both act as beneficial dopants or detrimental traps unlike Si where intentional shallow dopants and traps are distinctly different. Therefore, the role of defect states on CdTe solar cell performance, the effect of processing on defect states, and simple and effective characterization techniques must be investigated and identified. In this research the thin film n+-CdS/p-CdTe solar cells made with evaporated Cu as a primary back contact, are characterized by using the temperature dependence of the reverse bias diode current (J-V-T) to determine the energy levels of deep defects. The results of the J-V-T measurements on solar cells made at NJIT show that while modest amounts of Cu enhance cell performance, an excessive high temperature annealing step degrades device quality and reduces efficiency. This work addresses the error that can be introduced during defect energy level estimation if the temperature dependence of the carrier capture cross-section is neglected. Therefore, the location of traps is derived using a Shockley-Read-Hall recombination model with modified assumptions. A Cu-related deep level defect with activation energy of 0.57eV is observed for Cu evaporated back contact cells and an intrinsic defect with activation energy 0.89eV is found. Frequency dispersion in Capacitance-Voltage measurements confirms the presence of Cu-related deep level traps for cells with a Cu evaporated back contact, whereas no such defects are observed in carbon paste contact. The behavior is believed to be due to diffusion of excess Cu from the contact. It is further observed that majority carrier deep level traps (Cu-related or intrinsic) contribute differently to the degradation of electronic properties of the CdTe solar cells. A simple and effective characterization technique based on temperature dependent capacitance spectroscopy (TDCS) is used to identify majority carrier trapping defects in thin film n+-CdS/p-CdTe solar cell, made with evaporated Cu as a primary back contact. The distinct deep level traps, observed by TDCS seem to be due to the ionization of impurity centers located in the depletion region of n+-CdS/p-CdTe junction.
