All Title Author
Keywords Abstract

Characterization of Doped Amorphous Silicon Thin Films through the Investigation of Dopant Elements by Glow Discharge Spectrometry: A Correlation of Conductivity and Bandgap Energy Measurements

DOI: 10.3390/ijms12042200

Keywords: thin film solar cells, hydrogenated amorphous silicon, bandgap energy, ellipsometry, depth profiling analysis, glow discharge optical emission spectrometry

Full-Text   Cite this paper   Add to My Lib


The determination of optical parameters, such as absorption and extinction coefficients, refractive index and the bandgap energy, is crucial to understand the behavior and final efficiency of thin film solar cells based on hydrogenated amorphous silicon (a-Si:H). The influence of small variations of the gas flow rates used for the preparation of the p-a-SiC:H layer on the bandgap energy, as well as on the dopant elements concentration, thickness and conductivity of the p-layer, is investigated in this work using several complementary techniques. UV-NIR spectrophotometry and ellipsometry were used for the determination of bandgap energies of four p-a-SiC:H thin films, prepared by using different B 2H 6 and SiH 4 fluxes (B 2H 6 from 12 sccm to 20 sccm and SiH 4 from 6 sccm to 10 sccm). Moreover, radiofrequency glow discharge optical emission spectrometry technique was used for depth profiling characterization of p-a-SiC:H thin films and valuable information about dopant elements concentration and distribution throughout the coating was found. Finally, a direct relationship between the conductivity of p-a-SiC:H thin films and the dopant elements concentration, particularly boron and carbon, was observed for the four selected samples.


[1]  Cárabe, J; Gandía, JJ. Thin-film-silicon solar cells. Opto-Electron. Rev 2004, 12, 1–6.
[2]  Markvart, T; Casta?er, L. Practical Handbook of Photovoltaics: Fundamentals and Application; Elsevier Science Ltd: Kidlington, Oxford, UK, 2003; pp. 218–317.
[3]  Mercaldo, LV; Addonizio, ML; Della Noce, M; Delli Veneri, P; Scognamiglio, A; Privato, C. Thin film silicon photovoltaics: Architectural perspectives and technological issues. Appl. Energy 2009, 86, 1836–1844.
[4]  Hegedus, S. Progress in Photovoltaics: Research and Application; John Wiley & Sons Ltd: Chichester, UK, 2006; pp. 393–411.
[5]  Poortmans, J; Arkhipov, V. Thin Film Solar Cells; John Wiley & Sons Ltd: Chichester, UK, 2006; pp. 194–196.
[6]  Stapinski, K; Swatowski, B; Kluska, S; Walasek, E. Optical and structural properties of amorphous silicon-carbon films for optoelectronic applications. Appl. Surf. Sci 2004, 238, 367–374.
[7]  Schropp, REI; Zeman, M. Amorphous and Microcrystalline Silicon Solar Cells: Modeling Material and Device Technology; Kluwer Academic Publishers: Norwell, MA, USA, 1998; pp. 41–68.
[8]  Jellison, GE. Spectroscopic ellipsometry data analysis: measured versus calculated quantities. Thin Solid Films 1998, 313–314, 33–39.
[9]  Centurioni, E; Desalvo, A; Pinghini, R; Rizzoli, R; Summonte, C; Zignani, F. Effect of hydrogen plasma treatments at very high frequency in p-type amorphous and microcrystalline silicon films. In Microcrystalline and Nanocrystalline Semiconductors; Sailor, MJ, Tsai, CC, Canham, LT, Tanaka, K, Eds.; Materials Research Society Symposia Proceedings: Boston, MA, USA, 1999; pp. 517–522.
[10]  Iliopoulos, E; Adikimenakis, A; Giesen, C; Heuken, M; Georgakilas, A. Energy bandgap bowing of InAlN alloys studied by spectroscopic ellipsometry. Appl. Phys. Lett 2008, 92, 191907.
[11]  Park, J-W; Hwan Eom, S; Lee, H; Da Silva, JLF; Kang, Y-S; Lee, T-Y; Khang, YH. Optical properties of pseudobinary GeTe, Ge2Sb2Te5, GeSb2Te4, GeSb4Te7, and Sb2Te3 from ellipsometry and density functional theory. Phys. Rev. B 2008, 80, 115209.
[12]  Liu, C; Erdmann, J; Maj, J; Macrander, A. Thickness determination of metal thin films with spectroscopic ellipsometry for x-ray mirror and multilayer applications. J. Vac. Sci. Technol. A 1999, 17, 2741–2148.
[13]  Ferrari, S; Modreanu, M; Scarel, G; Fanciulli, M. X-Ray reflectivity and spectroscopic ellipsometry as metrology tools for the characterization of interfacial layers in high-k materials. Thin Solid Films 2004, 450, 124–127.
[14]  Bernhard, C; Humlicek, J; Keimer, B. Far-infrared ellipsometry using a synchrotron light source-the dielectric response of the cuprate high Tc superconductors. Thin Solid Films 2004, 455–456, 143–149.
[15]  Pisonero, J; Fernández, B; Günther, D. Critical revision of GD-MS, LA-ICP-MS and SIMS as inorganic mass spectrometric techniques for direct solid analysis. J. Anal. Atom. Spectrom 2009, 24, 1145–1160.
[16]  Escobar-Galindo, R; Gago, R; Lousa, A; Albella, JM. Comparative depth-profiling analysis of nanometer-metal multi-layers by ion-probing techniques. Trends Anal. Chem 2009, 28, 494–505.
[17]  Fernández, B; Pereiro, R; Sanz-Medel, A. Glow discharge analysis of nanostructured materials and nanolayers-A review. Anal. Chim. Acta 2010, 679, 7–16.
[18]  Pisonero, J; Fernández, B; Pereiro, R; Bordel, N; Sanz-Medel, A. Glow-discharge spectrometry for direct analysis of thin and ultra-thin solid films. Trends Anal. Chem 2006, 25, 11–18.
[19]  Glow Discharge Plasmas in Analytical Spectroscopy; Marcus, RK, Broekaert, JAC, Eds.; John Wiley & Sons Ltd: Chichester, UK, 2003.
[20]  Winchester, MR; Payling, R. Radio-frequency glow discharge spectrometry: A critical review. Spectrochim. Acta Part B 2004, 59, 607–666.
[21]  Sanchez, P; Fernández, B; Menéndez, A; Pereiro, R; Sanz-Medel, A. Pulsed radiofrequency glow discharge optical emission spectrometry for the direct characterisation of photovoltaic thin film silicon solar cells. J. Anal. Atom. Spectrom 2010, 25, 370–377.
[22]  Centurioni, E. Generalized matrix method for calculation of internal light energy flux in mixed coherent and incoherent multilayer. Appl. Optics 2005, 44, 7532–7539.
[23]  Summonte, C; Rizzoli, R; Desalvo, A; Zignani, F; Centurioni, E; Pinghini, R; Bruno, G; Losurdo, M; Capezzuto, P; Gemmi, M. Plasma enhanced chemical vapor deposition of microcrystalline silicon: on the dynamics of the amorphous-microcrystalline interface by optical methods. Phil. Mag. B 2000, 80, 459–473.
[24]  Summonte, C; Rizzoli, R; Desalvo, A; Zignani, F; Centurioni, E; Pinghini, R; Gemmi, M. Very high frequency hydrogen plasma treatment of growing surfaces: a study of the p-type amorphous to microcrystalline silicon transition. J Non-Crystal Solids 2000, 266–269, 624–629.
[25]  Bruggeman, DAG. Berechung verschiedener physikalischer. Konstanten von heterogenen Substanzen. Ann. Phys 1935, 24, 636–679.
[26]  Fernández, B; Bordel, N; Pereiro, R; Sanz-Medel, A. The effect of thin conductive layers on glass on the performance of radiofrequency glow discharge optical emission spectrometry. J. Anal. Atom. Spectrom 2005, 20, 462–466.
[27]  Menéndez, A; Bordel, N; Pereiro, R; Sanz-Medel, A. Radiofrequency glow discharge optical emission spectrometry for the analysis of metallurgical-grade silicon. J. Anal. Atom. Spectrom 2005, 20, 233–235.
[28]  Jellison, GE, Jr; Modine, FA. Parameterization of the optical functions of amorphous materials in interband region. Appl. Phys. Lett 1996, 69, 371–373.
[29]  Morigaki, K. Physics of Amorphous Semiconductors; Imperial College Press and World Scientific Publishing: London, UK, 1999; pp. 137–149.
[30]  Hoffmann, V; Dorka, R; Wilken, L; Hodoroaba, VD; Wetzig, K. Present possibilities of thin-layer analysis by GDOES. Surf. Interface Anal 2003, 35, 575–582.


comments powered by Disqus