n+ polycrystalline silicon thin film emitter used as a seed layer for solid phase epitaxy

N. BUDINI; R. H. BUITRAGO; J. A. SCHMIDT; G. RISSO; P. A. RINALDI; R. D. ARCE

Valencia

Conferencia; 25th European Photovoltaic Solar Energy Conference; 2010

We worked on the solid phase epitaxial crystallisation of a lightly boron doped (p–) silicon layer on a heavily phosphorous doped (n+) polycrystalline emitter seed layer. Nickel-induced crystallisation and postcrystallisation doping of intrinsic amorphous silicon thin films (~200 nm) were used to prepare the seed layer. Optical microscopy revealed a solid phase epitaxial growth, with grains growing in a columnar structure. UV reflectance measurements indicated that the films have a crystallinity fraction over 70 % after full crystallisation. Xray diffraction allowed us to analyze also the crystallinity of the final structure and the orientation of the crystals. Considering the design of a solar cell, we propose to obtain a polycrystalline silicon solar cell in a two step process: (1) the Ni-induced crystallisation and subsequent doping of the emitter used as a seed layer (n+); (2) the deposition and solid epitaxial growth of the absorber and back surface field layers (p–/p+) onto the emitter.