Large-grained polycrystalline silicon on glass for thin-film solar cells

Abstract

We have investigated the formation of large-grained polycrystalline silicon (poly-Si) films on glass for thin-film solar cells using the 'seed layer concept' which is based on the epitaxial thickening of a thin large-grained poly-Si template (seed layer). Due to the glass substrate all

Large-grained polycrystalline silicon films on glass by argon-assisted ECRCVD epitaxial thickening of seed layers

“…Details of this process have been presented elsewhere [1]. Briefly, a 300 nm thick Al film was deposited by DC magnetron sputtering onto Schott Borofloat33 glass.…”

“…This layer was removed by chemical-mechanical polishing (CMP) to form a smooth, poly-Si film on the glass substrate with an average surface roughness ðR a Þ of o0:5 nm and a thickness of about $100 nm. The film is characterised by large grains (up to $10 mm) and a preferred (1 0 0) orientation [1,2].…”

“…A possible way forward is to form thin, large grained poly-Si seeding layers below the softening point of glass and use these as templates for the low temperature epitaxial overgrowth of thicker absorber films. This concept has recently been investigated by a number of researchers [1][2][3]. The seeding layers have been formed by aluminiuminduced crystallisation (AIC) of amorphous silicon which can lead to large grain size ($10 mm and above) poly-Si films on glass [4][5][6][7].…”

Aluminum induced crystallization of strongly (111) oriented polycrystalline silicon thin film and nucleation analysis

“…The pc-Si thin film can be applied in many areas such as solar cells [1][2][3], thin film transistors (TFTs) [4] and flat panel displays. The general strategy of fabricating the pc-Si thin film is to recrystallize the amorphous silicon (α-Si) previously deposited on a substrate.…”

“…Generally, strongly (001) preferred orientation can be achieved at a low annealing temperature (below 400°C) and this orientation will recede when temperature rises [15]. Gall et al [3] reported that (001) orientation was obviously weakened (dropped to 60% of total grains) as annealing temperature went to 450°C. By contrast, (111) preferred orientation is supposed to be achieved at a higher annealing temperature.…”