Simulating the interface morphology of silver thick film contacts on n-type Si-(100) and Si-(111)

Abstract

Silver crystals at the interface of silver thick film contacts carry the current across such contacts and therefore govern the contact resistance. The crystals grow nearly exclusively in pits in the silicon surface, which form during contact formation before the crystals and hence determine the amount and size of crystals. We simulate the mechanism of pit formation at such contact interfaces by using a model based on the removal probability of silicon surface atoms. The model leads to good agreement between experimentally observed and simulated pits. The results enable the prediction of pit formation in dependence of contact processing parameters

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

“…The occurrence of such large and deep crystallites has been also reported by other authors [2,3,10]. They are significantly larger in size than those observed for Ag pastes on phosphorus-doped surfaces [9,22,23].…”

“…4. The marked crystallite imprints imply a former crystallite presence at these locations [22]. Different sizes of crystallite imprints can be observed, and also very large and thus deep imprints are apparent.…”

Impact of excess phosphorus doping and Si crystalline defects on Ag crystallite nucleation and growth in silver screen‐printed Si solar cells

“…A few Ag crystallites are grown into the Si emitter. The shapes of the Ag crystallites are determined by the Si crystal orientation‐dependent back‐bonding strength . Current paths are provided by means of multistep tunneling into the silver finger across nano‐Ag colloids in a thin glass layer close to the silicon emitter or through the Ag crystallites separated by a thin glass layer or possibly in direct contact with the silver finger (Figure ; ).…”

Low‐Ohmic Contacting of Laser‐Doped p‐Type Silicon Surfaces with Pure Ag Screen‐Printed and Fired Contacts

“…Different sizes of crystallite imprints can be observed; however, their estimated maximum penetration depths are less than about 80 nm. Hence, they are significantly smaller in size then those commonly observed for Ag‐Al contacts . Apparently, the number of imprints is significantly larger for the sample in Figure (a), which shows the lower ρ C ≈ 1.5 mΩ cm 2 in comparison with the sample in Figure (b) with the higher ρ C ≈ 7.5 mΩ cm 2 .…”

“…Two exemplary images are shown in Figure . The numerous clearly recognizable crystallite imprints imply a former crystallite presence at these locations . Different sizes of crystallite imprints can be observed; however, their estimated maximum penetration depths are less than about 80 nm.…”