Wang YY, Jin Q, Zhuang K, Choi JK, Nxumalo J. Band gap measurement by nano-beam STEM with small off-axis angle transmission electron energy loss spectroscopy (TEELS).
Ultramicroscopy 2020;
220:113164. [PMID:
33186852 DOI:
10.1016/j.ultramic.2020.113164]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 10/24/2020] [Accepted: 11/01/2020] [Indexed: 11/28/2022]
Abstract
An energy band gap measurement method based on nano-beam STEM with small off-axis angle valence band transmission electron energy loss spectroscopy (TEELS) is reported. The effect of multiple scattering event is removed by self-convolution method to obtain a single scattering loss function and a dielectric function is calculated from the single scattering valence band energy loss function through Kramers-Kronig (K-K) analysis. Optical band gaps are extracted from energy loss spectra and the imaginary part of the dielectric functions for crystalline and amorphous SiOx, SiNx, and SiON through linear fitting of on-set regions yielding results that are independent of sample thickness. The TEELS band gap data are consistent with those obtained from reflection electron energy loss spectroscopy (REELS) measurements.
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