Europhys. Lett, 48 (4), pp. 403-409 (1999)
Tunneling states in tetrahedrally bonded amorphous semiconductors
S. Dyrting, H.-P. Fang, K. Y. Szeto and Ping Sheng
Department of Physics, Hong Kong University of Science and
Clear Water Bay, Kowloon, Hong Kong, China
(received 10 May 1999; accepted in final form 20 September 1999)
PACS. 61.43Dq - Amorphous semiconductors, metals,
PACS. 61.43Bn - Structural modeling: serial-addition models, computer simulation.
PACS. 02.70Ns - Molecular dynamics and particle methods.
Using molecular dynamics, we construct a structural model of amorphous silicon which produces well-relaxed and long-lasting structures with radial distribution functions that agree well with experimental results. The model produces a sufficient number of double-well potentials with low asymmetries, enabling a structurally-explicit microscopic portrayal of tunneling states in covalently bonded amorphous systems. A new structural characterization method is used to identify the possible origin of the tunneling states in amorphous silicon. Based on the study of the short-range order, we suggest that the tunneling states in amorphous silicon are predominantly associated with dangling bonds.
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