Intragrain defects in polycrystalline silicon thin-film solar cells on glass by aluminum-induced crystallization and subsequent epitaxy

• Published in: Thin solid films Vol. 516; no. 18; pp. 6409 - 6412
• Main Authors: Liu, F., Romero, M.J., Jones, K.M., Norman, A.G., Al-Jassim, M.M., Inns, D., Aberle, A.G.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 31.07.2008; Elsevier Science
• Subjects: Condensed matter: structure, mechanical and thermal properties; CORRELATIONS; Cross-disciplinary physics: materials science; rheology; CRYSTALLIZATION; CRYSTALS; DEFECTS; DEPOSITION; EPITAXY; Exact sciences and technology; GLASS; GROWTH; Intragrain defects; Ion and electron beam-assisted deposition; ion plating; LAYERS; LEVELS; MATERIALS SCIENCE; Methods of deposition of films and coatings; film growth and epitaxy; MICROSTRUCTURE; ORIENTATION; ORIGIN; Physics; Polycrystalline silicon; Renewable energy; SEEDS; SILICON; SOLAR CELLS; SOLAR ENERGY; Solar Energy - Photovoltaics; STACKING FAULTS; Structure and morphology; thickness; SURFACES; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Theory and models of film growth; Thin film solar cells; Thin film structure and morphology; WAVELENGTHS; Renewable energy; Intragrain defects; Polycrystalline silicon; Thin film solar cells; Conduction bands; Crystal defects; Stacking faults; Epitaxial layers; Defect level; Epitaxy; Crystallization; Polycrystals; Crystal seeds; Aluminium; Ion beam assisted deposition method; Grain orientation; Crystal perfection; Thin films; Energy gap; Thin film devices; Growth mechanism; Silicon; Microstructure
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2008.01.020

The origin of intragrain defects in polycrystalline silicon films grown by ion-assisted deposition (IAD) on aluminum-induced crystallization seed layers on glass is investigated. The microstructure of these polycrystalline Si films is bimodal, with near defect-free regions of orientation along the growth direction and highly defective regions containing smaller grains of orientation. In the defective regions, the dominant structural defects are twins in the seed layer and stacking faults in the IAD-grown epitaxial layer, both lying on {111} planes. The stacking faults originate at the seed layer surface due to surface imperfections, indicating that the quality of the seed layer surface plays an important role for the quality of the epitaxial Si film. We find a clear correlation between the structural crystal quality and defect-related radiative transitions at sub-bandgap wavelengths. Two dominant defect levels (~ 0.20 eV and ~ 0.29 eV below the conduction band edge) are observed and identified as impurity-related.