Fourier transform infrared Raman spectroscopy for probing semiconductor substrates beneath epitaxial films
Received:February 01, 2020  Revised:January 05, 2021  download
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Author NameAffiliationE-mail
WANG Wei School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China 
916939046@qq.com 
CHEN Xi-Ren State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China xrchen@mail.sitp.ac.cn 
YU Deng-Guang School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China ydg017@usst.edu.cn 
SHAO Jun State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China jshao@mail.sitp.ac.cn 
Abstract:High-quality semiconductor thin films are the basis for high-performance optoelectronic devices, of which the optoelectronic properties are restricted by the substrates. Experimental evaluation of the substrate beneath the thin films is therefore crucial for optimizing film growth. Unfortunately, such evaluation of substrates is usually severely affected by the capping thin films. This paper reports a Fourier transform (FT) Raman spectroscopic method, which utilizes the deep penetration characteristics of infrared pumping light with low photon energy, reduces the influence of the capping film, and extracts the Raman scattering information of the semiconductor substrate effectively. Application to CdTe thin films on GaAs-substrate demonstrates suppression of the CdTe while enhancement of the GaAs-substrate Raman scattering, as compared to a conventional Raman method. The signal-to-noise ratio of the spectrum exceeds 70, indicating the FT-Raman method a feasible approach for experimentally probing semiconductor substrate beneath thin films and/or multilayer structure.
keywords:infrared Raman  Fourier transform  CdTe/GaAs thin film  signal-to-noise ratio(SNR)
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