摘要:

We have investigated the effect of the CdS/CdTe interdiffusion on the properties of the CdTe films and the CdS/CdTe cell performance. Sulfur (S) diffusion into the CdTe films leads to a decreased defect density in the films, improvement of cell performance, and possibly to the increase of the carrier lifetime in the films. Cell performance is improved with the increase of the amount of S in the CdTe films. S diffusion into CdTe also deteriorates the uniformity of the CdS window layers, resulting in worse cell performance. Based on this study, we propose a processing method to improve cell performance. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57898

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

CdS/CdTe/ZnTe:Cu/Au solar cells were fabricated and tested under stressed conditions including enhanced temperature, forward and reverse bias, open circuit, dark and light. Discussion of results was focused mostly on the development of the back contact Schottky diode (increase in series resistance). Changes in the cell parameters were detected based on the analysis of the dynamic resistance of a cell (dV/dJ) at forward biases. A possible role of electromigration of the Cu dopant was discussed. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57899

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Our team has been investigating the use of particle-based contacts in both Si and CdTe solar cell technologies. First, in the area of contacts to Si, powders of Al and Ag prepared by an electroexplosion process have been characterized by transmission electron microscopy (TEM), TEM elemental determination X-ray spectroscopy (TEM-EDS), and TEM electron diffraction (TEM-ED). These Al and Ag particles were slurried and tested as contacts to p- and n-type silicon wafers, respectively. Linear current-voltage (I-V) was observed for Ag on n-type Si, indicative of an ohmic contact, whereas the Al on p-type Si sample was non-ideal. A wet-chemical surface treatment was performed on one Al sample and TEM-EDS indicated a substantial decrease in the O contaminant level. The treated Al on p-type Si films exhibited linear I-V after annealing. Second, in the area of contacts to CdTe, particles of Hg-Cu-Te and Sb-Te have been applied as contacts toCdTe/CdS/SnO2heterostructures prepared by the standard NREL protocol. First, Hg-Cu-Te and Sb-Te were prepared by a metathesis reaction. AfterCdCl2treatment and NP etch of the CdTe layer, particle contacts were applied. The Hg-Cu-Te contacted cells exhibited good electrical characteristics, withVoc>810&hthinsp;mVand efficiencies > 11.5&percent; for most cells. AlthoughVoc>800&hthinsp;mVwere observed for the Sb-Te contacted cells, efficiencies in these devices were limited to 9.1&percent; presumably by a large series resistance (>20 &OHgr;) observed in all samples. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57967

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

SnO2:Ffilms produced by continuous APCVD from tin tetrachloride are an attractive candidate in the choice of the most appropriate materials of thin film solar cells. The purpose of developing this technology is to fabricate excellentSnO2films while maintaining its advantages of large-scale manufacture and low cost. Among others, it is important to design an injector that is able to provide a stable reactant gas flow with uniform distribution in speed, composition and temperature. Hall measurement, Seebeck coefficient and ellipsometry measurements are used to provide the carrier concentration, mobility and other information about the properties of the films. The characterization shows that the main properties of the films deposited by continuous APCVD are close to or better than that of the commercial products fabricated by other technologies. Finally, the different measurements are discussed. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57968

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Atmospheric Pressure Chemical Vapor Deposition (APCVD) of polycrystalline thin-film CdTe appears to offer several practical advantages over state-of-the-art manufacturing techniques. APCVD employs the same reaction chemistry utilized to produce 16&percent; efficient CdTe cells (i.e., same reaction chemistry as Close Spaced Sublimation), avoids use of vacuum equipment, allows for physical separation of the source and substrate, and employs forced convection to ensure uniform delivery of source material over large-area substrates. Reactor design considerations and preliminary numerical simulations of mass transport are presented. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57969

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

We report changes in the photoluminescence spectra associated with the diffusion of Cu in CdTe thin films used in CdTe/CdS solar cells. Films grown by vapor transport deposition and radio-frequency sputtering as well as single crystal CdTe were included in the study. The main effects of Cu diffusion appear to be the quenching of a donor-acceptor transition associated with Cd vacancies and the increase in intensity of a lower energy broad-band transition. The PL is subsequently used to explore the effects of electric fields on Cu diffusion. The role of Te as a diffusion barrier for Cu is investigated. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57970

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

In this paper, we have studied the effect of high-resistanceSnO2buffer layers, deposited by low-pressure chemical-vapor deposition, on CdS/CdTe device performance. Our results indicate that when CdS/CdTe devices have a very thin layer of CdS or no CdS at all, thei-SnO2buffer layer helps to increase device efficiency. When the CdS layer is thicker than 600 Å, the device performance is dominated by CdS thickness, not thei-SnO2layer. If a very thin CdS layer is to be used to enhance device performance, we conclude that a betterSnO2buffer layer is needed. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57900

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

A dry vapor treatment ofCdCl2is being developed as an alternative approach to the conventional solutionCdCl2treatment of CdS/CdTe devices. In this alternative process, the CdS/CdTe substrates are vapor treated in a close-spaced sublimation configuration. A 16-run Plackett-Burman screening experiment identified source temperature, substrate temperature, and treatment time as being the most significant parameters in the process. Subsequently, a 20-run Central Composite Design showed that a source temperature of 380–390&hthinsp;°C, a temperature gradient (&Dgr;T) of 5&hthinsp;°C, and a time of 10 minutes provides the most process tolerant combination, yielding a total-area efficiency of 12.6&percent;. A strong interaction between &Dgr;T and treatment time was also identified. The model indicated that for a small &Dgr;T, device performance improved with decreasing time, whereas at larger values of &Dgr;T, performance increased with increasing time. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57971

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

We have investigated the effect of deposition conditions ofSnO2films, deposited by chemical vapor deposition using tin tetrachloride and tetramethyltin precursors, on the film properties. The type of precursor and the deposition temperature affect the morphology of the films. The structure of the films is determined by the deposition temperature: films deposited at low temperatures show a mixed SnO andSnO2phase. The processing temperature and type of substrate determine the impurity content in the films. Electrical properties (e.g., the carrier mobility) and optical properties of the films are affected by the structure and the impurity content in these layers. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57901

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

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&hthinsp;°C to 300&hthinsp;°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. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57902

出版商:AIP    

年代:1999

数据来源: AIP