Martins, R., Ferreira Cabrita Fortunato I. A. E. "
Improvement of a-Si:H device stability and performances by proper design of the interfaces."
Journal of Non-Crystalline Solids. 266-269 B (2000): 1094-1098.
AbstractThis paper deals with a new design method for the interfaces of a-Si:H pin solar cells that improves the stability and performances of devices deposited in a single batch chamber process. The method consists in removing a deposited sacrificial layer placed between the p/i and/or i/n interfaces by etching. This layer is an absorber of defects and impurities that are introduced in the interfaces, mainly from the chamber walls cross-contamination and the substrate surface. The results achieved increase the device fill factor and short circuit current density, respectively towards 75% and 16.3 mA cm-2, with a final efficiency of about 10%, before light soaking experiments. © 2000 Elsevier Science B.V. All rights reserved.
de Nunes de Carvalho, C., Nijs Ferreira Fortunato Martins J. M. M. I. "
Improvement of the ITO-p interface in a-Si:H solar cells using a thin SiO intermediate layer."
Materials Research Society Symposium - Proceedings. Vol. 420. 1996. 861-865.
AbstractThe use of ITO thin films on glass/ITO/p-i-n/metal amorphous silicon solar cells is reviewed. It is suggested a new application for silicon monoxide thin films on the ITO-p interface, as an intermediate layer, to minimize the ITO thin film deterioration process, during the early stage of exposure to a silane plasma rich in hydrogen. The thickness of the silicon monoxide thin films is chosen not to worsen the optical and electrical properties of the ITO thin films. The ITO-p interface is optimized (due to impurities diffusion decrease), leading to an overall improvement of the device performance.
Ferreira, I., Vilarinho Fernandes Fortunato Martins P. F. E. "
Influence of hydrogen gas dilution on the properties of silicon-doped thin films prepared by the hot-wire plasma-assisted technique."
Key Engineering Materials. 230-232 (2002): 591-594.
AbstractP- and n-type silicon thin films have been produced using a new hot wire plasma assisted deposition process that combines the conventional plasma enhanced chemical vapor deposition and the hot wire techniques. The films were produced in the presence of different hydrogen gas flow and their optoelectronic, structural and compositional properties have been studied. The optimized optoelectronic results achieved for n-type Si:H films are conductivity at room temperature of 9.4(Ωcm)-1 and optical band gap of 2eV while for p-type SiC:H films these values are 1 × 10-2(Ωcm)-1 and 1.6eV, respectively. The films exhibit the required optoelectronic characteristics and compactness for device applications such as solar cells.
Raniero, L., Gonçalves Pimentel Ferreira Zhang Pereira Águas Fortunato Martins A. A. I. "
Influence of hydrogen plasma on electrical and optical properties of transparent conductive oxides."
Materials Research Society Symposium Proceedings. Vol. 862. 2005. 543-548.
AbstractIn this work we study the optical and electrical behavior of ZnO:Ga, ITO and IZO films deposited on glass after sustaining different hydrogen plasma conditions and exposure times. This work was complemented by analyzing the surface morphology of the set of films, which allow us to determine the role of hydrogen plasma on the film's properties such as Hall mobility, free carrier concentration, sheet resistance, optical transmittance, figure of merit and state of the surface. Apart from that, the performances of solar cells using an intrinsic layer constituted by nanocrystalline silicon will be also presented. The data show that the electrical properties of solar cells were improved by using ZnO:Ga as front contact, allowing a high current density collection and single pin solar cells with efficiencies exceeding 11%. © 2005 Materials Research Society.