Title: High Efficiency a-Si/c-Si Heterojunction Solar Cells
Speaker: Prof. Dr. W. R. Fahrner, Chair of Electronic Devices, Hagen University, Germany
Time：Sep 9 2009 10:00(AM)
Venue：Institute of Semiconductors, CAS
Abstract
The talk starts with a general survey on the properties of heterojunction solar cells. The structure, composition, and the functions of the various layers are discussed. Point by point the numerous challenges are tackled. It is known that surface states have a detrimental impact on the performance. Thus two independent measurement techniques, a direct and an indirect one, have been developed in order to determine the surface state density and the capture cross sections. An appropriate texture is mandatory for suppression of the reflection. A reasonable tool for this purpose is etching by TMAH (Tetra Methyl Ammonium Hydroxide). Another issue is the formation of an epitaxial interface layer instead of an amorphous one. This must be prevented by avoiding deposition temperatures above 200° C. Passivation of the surfaces is done by means of intrinsic a-SiO:H layers annealed at 250° C. Our (micromorphous) emitter is deposited below this temperature at a high hydrogen dilution.
The talk is accompanied by a brief introduction into the distance teaching system of the University of Hagen (the national distance teaching university of Germany).
About Prof. Dr. W. R. Fahrner
Prof. Dr. Wolfgang R. Fahrner received his degree in physics from the University of Freiburg, Germany, in 1970. From 1970 to 1977, he was employed by the Institute of Applied Solid State Physics of the Fraunhofer Society in Freiburg. His main subject was the effect of ion implantation in MOS devices. In 1973, he received his Ph.D. degree. In 1973 and 1974, he was given a sabbatical research stay at IBM East Fishkill, N.Y. In 1977, he joined the Hahn-Meitner Institute, Berlin, where he investigated radiation effects in electronic devices. In 1984 and 1985, he again worked for IBM, East Fishkill. In 1988, he was appointed full professor at the University of Hagen, where he now heads the chair of electronic devices. His main activities are solar cell technology, thermoelectrical devices, and hydrogen-silicon interaction.
Prof. Fahrner has authored or co-authored more than 800 reviewed papers, 15 patents and nine books. He is a member of the Electrochemical Society and of the German Physical Society and a senior member of the IEEE.