Quantification of point and line defects in Si0.6Ge0.4 alloys with thickness variation via optical pump-THz probe measurement

Jonghoon Kim, Kwangsik Jeong, Min Baik, Dae Kyoung Kim, Jimin Chae, Hanbum Park, Seok Bo Hong, Dae Hong Ko, Mann Ho Cho

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1 Citation (Scopus)


Measuring defect density through non-contact, non-destructive methods without any additional sample processing has been of great interest in both academia and industry. In this study, we propose a new method to quantify the point and line defect densities of Si0.6Ge0.4 films by using the recombination time of the photoexcited carrier, as well as the optical pump THz probe method (OPTP). The change in the crystallinity of Si0.6Ge0.4 obtained from various measurements was consistent with the recombination time of the point- and line-defect states in OPTP, which changed from 107 ps to 172 ps and from 3961 ps to 870 ps, respectively. The actual defect density of each sample was extracted from photoinduced current transient spectroscopy (PICTS) for comparison with the recombination time. In addition, the non-Drude behavior of the photoexcited carrier was analyzed using two-dimensional terahertz time-domain spectroscopy (2D-TDS), which corresponds with previous measurement tools. The quantification methodology proposed in this study is expected to be advantageous to both academia and industry, as it will enable fast and accurate analysis of defects without requiring further sample processing.

Original languageEnglish
Article number145815
JournalApplied Surface Science
Publication statusPublished - 2020 May 30

Bibliographical note

Funding Information:
This research was supported by a joint industry–academy research program between Samsung Electronics and Yonsei University and the Nanomaterial Technology Development Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science, ICT, and Future Planning ( NRF-2016M3A7B4910398 ) and through an NRF grant funded by the Korean government (MSIP) (2018R1A2A1A05023214). Experiments are partially performed using the fs-THz spectroscopy beamlines at Pohang Light Source (PLS).

Publisher Copyright:
© 2020 Elsevier B.V.

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces


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