"Recent Progress of the ""Micromorph"" TANDEM Solar Cells"

p. Fischer, H. Keppner, U. Kroll,P. Torres, J. Meier, R. Platz, S. Dubail, J.A. Anna Selvan,.N. PellatonVaucher, Y. Ziegler, R. Tscharner, C\). Hof, N. Beck, M. Goetz, P. Pemet,M. Goerlitzer, N. Wyrsch, J.Vuille, J. Cuperus, A. Shah; ,: 'Institut de Microtechnique, Universite de Neuchâtel, rue Breguet 2, CH-2000 Neuchâtel, Switzerland;Tel: 41 3271'83200, Fax: 41 327183201, E-mail: fischer@iint.unine.chhttp://www-micromorph.unine.cuAbstract: The paper gives an overview over recent results and future potentials of the cornbined ainorphoussilicon/microcrys~alline silicon "micromorph" tandem cell technology. The reported results includereplacement of boron-microdoping compensation by employment of gas-purification to obtain mid-gapiriicrocrystailine silicon, leading to tne fabrication of a 3.6 ~m thick microcrystalline silicon p-i-n cell with7. 7% s~ble efficiency. lncreased the deposition rate of microcrystalline by SiH4fAr/H2 plasma depositionresults in a 3.1 % efficient microcrystalline single-junction solar cell deposited at 3.0 ~rn/hour. Further,micromorph tandem cells with 13% initial, or with 10.7% (confirmed by ISE-FhG Freiburg) stabilizedefficiency arereported on. The realization of over 13 mA/cm2,current generation in a 1500 A thick a-Si:H topcell by combining high temperature deposi~on-and a ZnO intermediate reflector layer demonstrates thepotential to yet significantly decrease the top cell degradation in the micromorphtandem cell.Keywords: Micro Crystalline Si -1 : a-Si -2 : Tandem -3