Dresden 2003 – scientific programme
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DS: Dünne Schichten
DS 23: Elektrische und optische Eigenschaften II
DS 23.1: Talk
Thursday, March 27, 2003, 15:15–15:30, GER/38
Electrical properties of low-temperature epitaxial thin Silicon films — •Ulla Knipper, Björn Rau, Jutta Schwarzkopf, Stephan Brehme, and Walther Fuhs — Hahn-Meitner-Institut Berlin, Abt. Silizium-Photovoltaik, Kekuléstr. 5, D-12489 Berlin
We have investigated the electrical properties of epitaxial Si films grown by Electron-Cyclotron Resonance Plasma-Enhanced Chemical-Vapor Deposition (ECR-PECVD) on Si(100)-wafers at deposition temperatures between 420 oC and 560 oC.
To reduce the substrate influence on lateral measurements, hetero-type substrates were used building up pn-junctions. Hall effect (HE) measurements showed n-type conductivity of nominally undoped films with free carrier concentrations in the range 1× 1016−2× 1017 cm−3 at room temperature. We observed at lower temperatures a transition from freeze-out range to defect band conduction which is connected to higher trap densities. In samples with lower trap densities we found low activation energies in the freeze-out range as to be expected in this concentration range. HE measurements showed different degrees of substrate influence according to the IV curves measured at the same structures. In addition we prepared Schottky barrier diodes of the type Au/epi-Si/Si(n+) by depositing on highly doped substrates. The results of the electrical characterization and in particular of capacitance measurements will be compared with those of the HE measurements.