Micro/nano pillar arrays can be a promising architecture for high efficiency solar cells based on less expensive photovoltaic materials with short minority carrier diffusion lengths (Ln, p). To investigate design tradeoffs of the radial junction array solar cells, we fabricated 25 µm-tall c-Si pillar array devices having different diameters and pillar filling ratio. The high-aspect-ratio radial p+-n+ junctions were formed by gas phase diffusion of an n-type dopant into etched p-type Si pillars. The c-Si pillar arrays showed clear rectifying properties. The spectral reflectance decreased with the pillar filling ratio increase from 0.2 to 0.5, but no subsequent decrease was observed above the filling ratio of 0.5. On the other hand, approximately two times higher cell efficiency was obtained with an 8 µm diameter (<1 Ln) pillar array than with a 32 µm diameter (>3 Ln) pillar array having the same pillar filling ratio.
Conference Dates: June 19-24, 2011
Conference Location: Seattle, WA
Conference Title: Photovoltaic Specialist Conferences, 2011
Pub Type: Conferences
etched pillar array, solar cells, microwire, silicon