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.
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.
Download or read book Handbook of II VI Semiconductor Based Sensors and Radiation Detectors written by Ghenadii Korotcenkov and published by Springer Nature. This book was released on 2023-04-20 with total page 585 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three-volumes book “Handbook of II-VI Semiconductor-Based Sensors and Radiation Detectors” is the first to cover both chemical sensors and biosensors and all types of photodetectors and radiation detectors based on II-VI semiconductors. It contains a comprehensive and detailed analysis of all aspects of the application of II-VI semiconductors in these devices. The first volume "Materials and Technologies" of a three-volume set describes the physical, chemical and electronic properties of II-VI compounds, which give rise to an increased interest in these semiconductors. Technologies that are used in the development of various devices based on II-VI connections, such as material synthesis, deposition, characterization, processing, and device fabrication, are also discussed in detail in this volume. It covers also topics related to synthesis and application of II-VI-based nanoparticles and quantum dots, as well their toxicity, biocompatibility and biofunctionalization.
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.
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.
Download or read book Effects of Cu Diffusion from ZnTe Cu Ti Contacts on Carrier Lifetime of CdS CdTe Thin Film Solar Cells written by and published by . This book was released on 2008 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
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.
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:
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.
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.
Download or read book CdTe CdS Thin Film Solar Cells Fabricated on Flexible Substrates written by Vasilios Palekis and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cadmium Telluride (CdTe) is a leading thin film photovoltaic (PV) material due to its near ideal bandgap of 1.45 eV and its high optical absorption coefficient. The typical CdTe thin film solar cell is of the superstrate configuration where a window layer (CdS), the absorber (CdTe) and a back contact are deposited onto glass coated with a transparent electrode. Substrate CdTe solar cells where the above listed films are deposited in reverse are not common. In this study substrate CdTe solar cells are fabricated on flexible foils. The properties of the Molybdenum back contact, Zinc Telluride (ZnTe) interlayer and CdTe absorber on the flexible foils were studied and characterized using X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). Substrate curvature and film flaking was observed during the fabrication as a result of differences in thermal expansion coefficients between the substrate and the deposited films, and also due to impurity diffusion from the foil into the film stack. In order to overcome this problem diffusion barriers where used to eliminate contamination. Silicon dioxide (SiO2), silicon nitride (Si3N4) and molybdenum nitride (MoxNy) were used as such barriers. Electrical characterization of completed devices was carried out by Current-Voltage (J-V), Capacitance-Voltage (C-V) and Spectral Response (SR) measurements. Roll-over was observed in the first quadrant of J-V curves indicating the existence of a back barrier due to a Schottky back contact. The formation of non-rectifying contact to p-CdTe thin-film is one of the major and critical challenges associated with the fabrication of efficient and stable solar cells. Several materials (ZnTe, Cu, Cu2Te, and Te) were studied as potential candidates for the formation of an effective back contact.
Download or read book SIMS Analysis of Cu in ZnTe based Back Contacts for CdTe CdS Solar Cells written by Chitra Narayanswamy and published by . This book was released on 1999 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
Download or read book Effect of Heating Ion Beam Milling and ZnTe Cu Deposition on the Spectroscopic Cathodoluminescence of Polycrystalline CdTe Preprint written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented at the 2001 NCPV Program Review Meeting: Cathodoluminescence used to study evolution of electro-optical properties of back surface of CdS/CdTe during initial steps of fabricating NREL ZnTe:Cu contact.
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.
Download or read book ZnTe written by and published by . This book was released on 2003 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to produce high-performance CdS/CdTe photovoltaic (PV) devices that incorporate high-transparency back contacts for multijunction thin-film PV applications will require an even greater level of understanding than has been required for single-junction devices. This study reports some of our initial investigations at NREL to modify the ZnTe:Cu contact process previously developed for single-junction applications for optimal use as a transparent back contact. We have succeeded in producing devices incorporating a transparent ZnTe:Cu/ITO/metal-grid contact that demonstrates nominally identical light I-V (LIV) performance to the ZnTe:Cu/Ti contact used in single-junction devices. However, we have determined that the transparent conducting oxide (TCO), CdS, CdTe, and ZnTe:Cu layers are all factors in the optical absorption within the device. Finally, we have concluded that optimizing the transparent ZnTe:Cu contact for use with NREL-produced device material will require a more detailed understanding of the evolution of the junction region during the contact process.
