Introduction to Silicon Heterojunction Solar Cells

Solar energy demand is growing rapidly due to rapid increase in world¿s population, power utilization and living life style. Silicon based solar cells are best alternate to fulfil energy need of world¿s population. The c-Si/a-Si:H heterojunction solar cells have remarkable advantages over c-Si and also a-Si:H based solar cells. The conversion efficiency of c-Si/a-Si:H heterojunction solar cells is comparable with c-Si based solar cells. The c-Si/a-Si:H heterojunction solar cells can be easily fabricated at temperature below 200oC, whereas junction formation in conventional c-Si solar cells is usually done by a thermal diffusion step, for which temperature of 800-1000 oC is needed. This low temperature enables the use of thinner wafers, thermal budget during the heterojunction formation is also considerably reduced compared to homojunction formation. The heterojunction silicon solar cells exhibit a smaller drop in performance with increasing temperature in comparison with conventional c-Si solar cells. In heterojunction solar cells improved surface passivation and reduced recombination losses results in higher open circuit voltage values leads to high efficiency.