Directional growth and crystallization of silicon thin films prepared by electron-beam evaporation on oblique and textured surfaces

Abstract Electron-beam evaporation (EBE) of silicon permits the high-rate deposition of photovoltaic thin-film devices at low costs. The directional, non-conformal growth characteristic of EBE is systematically investigated by varying the silicon flux angle of incidence γ on the substrate surface between 0° and 49°. After solid phase crystallization the micro-structural properties of these silicon films are investigated and correlated with the electronic quality of n + / p − /p + -type solar cell stacks. As γ exceeds 30°, the porosity and oxygen content of the silicon films increase significantly coming along with the break-down of the electronic material quality. At γ >40° the silicon crystallization process is even found to be suppressed resulting from a columnar film morphology infiltrated by oxygen-rich pores. The knowledge of this critical angle is essential when textured substrates, consisting of many tilted micro-areas, are used for enhanced light absorption in the silicon film simultaneously ensuring the growth of high-quality material. Furthermore, the inclination angle γ can serve as design parameter for tailored substrate templates for the fabrication of advanced light-harvesting structures by self-organized solid phase crystallization.

[1]  A. Aberle,et al.  Solid phase crystallized polycrystalline thin-films on glass from evaporated silicon for photovoltaic applications , 2006 .

[2]  Tom J. Smy,et al.  Modelling and characterization of columnar growth in evaporated films , 1993 .

[3]  Philippe M. Fauchet,et al.  The effects of microcrystal size and shape on the one phonon Raman spectra of crystalline semiconductors , 1986 .

[4]  B. Rech,et al.  Texture etched ZnO:Al coated glass substrates for silicon based thin film solar cells , 1999 .

[5]  Bernd Rech,et al.  Crystallization kinetics in electron-beam evaporated amorphous silicon on ZnO:Al-coated glass for thin film solar cells , 2009 .

[6]  S. Dannefaer.  Defects in semiconductors , 1989 .

[7]  B. Rech,et al.  Influence of Hydrogen Plasma on the Defect Passivation of Polycrystalline Si Thin Film Solar Cells , 2009 .

[8]  Siegfried Schiller,et al.  Electron beam technology , 1982 .

[9]  Eli Yablonovitch,et al.  Optically enhanced amorphous silicon solar cells , 1983 .

[10]  D. A. Clugston,et al.  Crystalline silicon on glass (CSG) thin-film solar cell modules , 2004 .

[11]  Bernd Rech,et al.  Large‐area fabrication of equidistant free‐standing Si crystals on nanoimprinted glass , 2011 .

[12]  Christophe Ballif,et al.  Influence of the substrate geometrical parameters on microcrystalline silicon growth for thin-film solar cells , 2009 .

[13]  Bernd Rech,et al.  Polycrystalline silicon thin-film solar cells on glass , 2009 .

[14]  Sanjeev K. Gupta,et al.  Electron-beam assisted physical vapor deposition of polycrystalline silicon films , 2011 .

[15]  Toshiaki Baba,et al.  High-quality polycrystalline silicon thin film prepared by a solid phase crystallization method , 1996 .

[16]  B Rech,et al.  Large-area 2D periodic crystalline silicon nanodome arrays on nanoimprinted glass exhibiting photonic band structure effects. , 2012, Nanotechnology.

[17]  B. Rech,et al.  Development of a rapid thermal annealing process for polycrystalline silicon thin-film solar cells on glass , 2009 .

[18]  É. Bustarret,et al.  Experimental determination of the nanocrystalline volume fraction in silicon thin films from Raman spectroscopy , 1988 .

[19]  U. Heinzmann,et al.  Deposition of silicon oxide thin films in TEOS with addition of oxygen to the plasma ambient : IR spectra analysis , 2005 .

[20]  H. Leamy,et al.  Columnar microstructure in vapor-deposited thin films , 1977 .

[21]  Si‐Chen Lee,et al.  Effect of porosity on infrared‐absorption spectra of silicon dioxide , 1995 .

[22]  L. Ley,et al.  The one phonon Raman spectrum in microcrystalline silicon , 1981 .

[23]  A. Shah,et al.  Thin‐film silicon solar cell technology , 2004 .

[24]  Yi Cui,et al.  Light trapping in solar cells: can periodic beat random? , 2012, ACS nano.

[25]  A. Dillon,et al.  FTIR Studies of H2O and D2O Decomposition on Porous Silicon Surfaces , 1991 .

[26]  Bernd Rech,et al.  Direct growth of periodic silicon nanostructures on imprinted glass for photovoltaic and photonic applications , 2012 .

[27]  T. Young,et al.  Study on the Si–Si Vibrational States of the Near Surface Region of Porous Silicon , 2000 .

[28]  Leon Abelmann,et al.  Oblique evaporation and surface diffusion , 1997 .

[29]  Bernd Rech,et al.  Microstructure and photovoltaic performance of polycrystalline silicon thin films on temperature-stable ZnO:Al layers , 2009 .