Rei. Schropp et al., APPARENT GETTERING OF THE STAEBLER-WRONSKI EFFECT IN AMORPHOUS-SILICON SOLAR-CELLS, Solar energy materials and solar cells, 34(1-4), 1994, pp. 455-463
The stability behaviour of intrinsic amorphous silicon materials incor
porated in a p(+)-i-n(+) solar cell structure is considerably differen
t from that observed by electrical characterization methods in individ
ual thin films. This is due to the fundamental difference in Fermi-lev
el position in a single layer compared to the situation occurring in d
evices. We have employed the differences in the re-equilibration behav
iour that have been observed in various intrinsic materials when the F
ermi-level is shifted towards the valence band edge, in order to desig
n a cell with a new profiled i-layer which would possess an improved e
lectric field distribution after light soaking compared to cells with
a constant i-layer. The contribution of the interface region to the st
abilized conversion efficiency is greatly improved, whereas the first
50 nm of the cell structure remains unchanged. Thus, it appears that t
he Staebler-Wronski effect is gettered away from the junction, much li
ke the impurity gettering concept in crystalline solar cells.