Impact of boron doping profiles on the specific contact resistance of screen printed Ag–Al contacts on silicon

摘要: Abstract For the contacting of boron-doped emitters with screen-printed metallization in n-type silicon solar cells, usually a small amount aluminum is added to silver pastes. To date, low specific contact resistances ρ C range few mΩ cm 2 have only been achieved these so-called silver–aluminum (Ag–Al) Within this work, experimentally determined for two Ag–Al pastes three different on alkaline textured and passivated surfaces. The investigated boron doping profiles feature almost identical rising curve progressions up depth ≈60 nm (which corresponds depletion zone), maximum dopant concentration N max ≈8·10 19  cm −3 . However, they junction depths between 570 nm and 980 nm. This work shows that concentrations values well below following zone significantly affect measured : deeper junction, lower behavior observed both example, mean paste Ag–Al1 decreases from ≈4 mΩ cm , deep profile, ≈2 mΩ cm 980 nm one. By using an analytical model calculate dependence e.g. concentration, metal crystallite coverage fraction, penetration depth, can be explained by crystallites several 100 nm. calculations also reveal impact negligible respect than ≈100 nm.