C/sub 60//a-C superlattice structures for solar cell applications

Abstract

CSO I amorphous carbon (a-C) superlattice structures were fabricated by shutter controlled molecular beam deposition. A-C layers were transformed from CW by nitrogen ion bombardment. The dark and photo conductivity of Csda-C superlattice structures were measured by gapcell structure. The resulted films show high resistivity, and the photosensitivity ratio is ranged 9-16. It is thought that such low ypotosensitivity is caused by high defect density of 2.7~10 cm3 in the a-C layers.Use of hydrogen plasma in Ceo amorphization process, instead of nitrogen, reduces the spin defect density in two orders of magnitude. Hydrogen atoms effectively reduce the defect density of a-C films by etching the weak carbon bond structures and/or passivating the dangling bonds.