Theoretical and experimental study of semiconducting iron disilicide and its applications to thin film solar cells

• Main Author: Tan, Khing Hong
• Other Authors: Pey Kin Leong
• Format: Theses and Dissertations
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Microelectronics
• Online Access: https://hdl.handle.net/10356/42899
• Institution: Nanyang Technological University

Transition metal silicides have been studied extensively for many years due to their potential technological importance and applications. Recently, the semiconducting phase of iron disilicide (β-FeSi2) has received considerable attention due to its potential applications in optoelectronic and microelectronic areas. This is attributed to its direct bandgap of 0.86 eV that corresponds to ~1.5 µm of the optical fiber communication. In addition, β-FeSi2 is expected as a promising photovoltaic material with a theoretical conversion efficiency as high as 23% due to its ultrahigh optical absorption coefficient in the order of 105 cm-1 near the absorption edge. These properties, along with other features such as abundance of constituent elements, nearly lattice-matched to Si, and high thermal stability and oxidation resistance, have made β-FeSi2 one of the most attractive materials of choice for future generation thin film photovoltaic applications. In this work, both theoretical and experimental study of β-FeSi2 was explored. The theoretical study based on the first-principles calculations provides the fundamental understanding of various properties of β-FeSi2, including equilibrium crystal structure, bandgap properties, effects of native vacancy defects, and impurity doping in β-FeSi2. The experimental study involves the formation and structural, optical, and electrical characterization of sputtered and processed β-FeSi2 as well as eventual demonstration of semiconducting β-FeSi2-based heterojunction thin film solar cells on the Si platform.