The amorphous/crystalline silicon (a-Si/c-Si) heterostructure has recently attracted new interest due to higher open circuit voltage V(oc) and low temperature fabrication processes. By reducing the wafer thickness all these characteristics become a necessity, together with the requirement of a back reflecting mirror, to obtain an effective optical confinement. To this aim dielectric mirrors can be adopted in the rear side of the solar cells, together with a local process of laser fired back Al contact. Taking advantage of a-Si/SiN(x) passivation properties of c-Si surface a Bragg reflector configuration can be formed on the rear side of the c-Si wafer by Plasma Enhanced Chemical Vapor Deposition (PECVD) alternating several couples of a-Si/SiN(x) and choosing their thicknesses to maximize the reflectance inward the c-Si wafer in the NIR spectrum. In this work we have adopted this mirror on the rear side of an n-a-Si/i-a-Si/p-c-Si heterostructure solar cell to obtain a full low temperature process. The cell back contact has been ensured by an Al diffusion into the c-Si wafer promoted by Nd-YAG pulsed laser. The front cell contact has been enhanced by chromium silicide CrSi formation on top of the n-a-Si layer and ITO deposition followed by an Ag grid. A V(oc) of 681 mV and 94% of IQE at 1000 nm have been reached. (C) 2008 Elsevier B.V. All rights reserved.
Bragg reflector and laser fired back contact in a-Si:H/c-Si heterostructure solar cell / M., Tucci; L., Serenelli; E., Salza; L., Pirozzi; DE CESARE, Giampiero; Caputo, Domenico; M., Ceccarelli. - In: MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY. - ISSN 0921-5107. - 159-60:C(2009), pp. 48-52. (Intervento presentato al convegno Symposium on Advanced Silicon Materials Research for Electronic and Photovoltaic Applications held at the 2008 E-MRS Spring Meeting tenutosi a Strasbourg, FRANCE nel MAY 26-30, 2008) [10.1016/j.mseb.2008.09.026].
Bragg reflector and laser fired back contact in a-Si:H/c-Si heterostructure solar cell
DE CESARE, Giampiero;CAPUTO, Domenico;
2009
Abstract
The amorphous/crystalline silicon (a-Si/c-Si) heterostructure has recently attracted new interest due to higher open circuit voltage V(oc) and low temperature fabrication processes. By reducing the wafer thickness all these characteristics become a necessity, together with the requirement of a back reflecting mirror, to obtain an effective optical confinement. To this aim dielectric mirrors can be adopted in the rear side of the solar cells, together with a local process of laser fired back Al contact. Taking advantage of a-Si/SiN(x) passivation properties of c-Si surface a Bragg reflector configuration can be formed on the rear side of the c-Si wafer by Plasma Enhanced Chemical Vapor Deposition (PECVD) alternating several couples of a-Si/SiN(x) and choosing their thicknesses to maximize the reflectance inward the c-Si wafer in the NIR spectrum. In this work we have adopted this mirror on the rear side of an n-a-Si/i-a-Si/p-c-Si heterostructure solar cell to obtain a full low temperature process. The cell back contact has been ensured by an Al diffusion into the c-Si wafer promoted by Nd-YAG pulsed laser. The front cell contact has been enhanced by chromium silicide CrSi formation on top of the n-a-Si layer and ITO deposition followed by an Ag grid. A V(oc) of 681 mV and 94% of IQE at 1000 nm have been reached. (C) 2008 Elsevier B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
