Optical determination of In/sub x/Ga/sub 1-x/As composition on InP using a Fabry-Perot test structure

Previously we reported on an ex-situ optical reflectance technique for determining precise epilayer thicknesses and Al/sub x/Ga/sub 1-x/As composition using a Fabry-Perot test structure. The use of the test structure with the resulting high reflectivity modulation was critical for obtaining the high...

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Bibliographic Details
Main Authors: Paduano, Q.S., Weyburne, D., Xuesheng Chen
Format: Conference Proceeding
Language:English
Subjects:
Fabry-Perot
Indium phosphide
Instruments
Lattices
Optical modulation
Reflectivity
Semiconductor device modeling
Testing
Thickness measurement
Wavelength measurement
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Summary:Previously we reported on an ex-situ optical reflectance technique for determining precise epilayer thicknesses and Al/sub x/Ga/sub 1-x/As composition using a Fabry-Perot test structure. The use of the test structure with the resulting high reflectivity modulation was critical for obtaining the high precision. In this paper, we extend the technique to determine the composition and the lattice mismatch of In/sub x/Ga/sub 1-x/As epilayers grown on InP substrates. In our technique, a stack consisting of 7 pairs of In/sub x/Ga/sub 1-x/As/InP and a cavity layer are grown on an InP wafer. The optical reflectance spectrum from a 2 mm spot is then measured and fitted to a transfer matrix model to extract the composition and thickness. The selection ofthe wavelength range of 1600 nm to 2200 nm was critical for extracting the In/sub x/Ga/sub 1-x/As properties uniquely. The advantage of using this reflectance fitting technique over other conventional methods is the simplicity of the instrumentation and the potential for fast measurement speed (/spl sim/1 sec per point).
ISSN:1092-8669
DOI:10.1109/ICIPRM.1997.600048