Nickel silicide contact for copper plated silicon solar cells

Nickel-Copper metallization for silicon solar cells offers a cost effective alternative to

traditional screen printed silver paste technology. The main objective of this work is to

study the formation of nickel silicide contacts with and without native silicon dioxide SiO2.

The effect of native SiO2 on the silicide formation has been studied using Raman

spectroscopy, Rutherford backscattering spectrometry and sheet resistance

measurements which shows that SiO

2

acts as a diffusion barrier for silicidation at low

temperatures of 350°C. At 400°C the presence of SiO2 results in the increased formation

of nickel mono-silicide phase with reduced thickness when compared to samples without

any native oxide. Pre and post-anneal measurements of Suns Voc, photoluminescence and

Illuminated lock in thermography show effect of annealing on electrical characteristics of

the device. The presence of native oxide is found to prevent degradation of the solar cells

when compared to cells without any native oxide. A process flow for fabricating silicon

solar cells using light induced plating of nickel and copper with and without native oxide

(SiO2) has been developed and cell results for devices fabricated on 156mm wafers have

been discussed.