Spectroscopic ellipsometry models of GeSn alloys at varying temperatures

Citation Author(s):
Tufts University
Tufts University
Thomas E.
Tufts University
Submitted by:
Amanda Lemire
Last updated:
Fri, 05/31/2024 - 16:49
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Three Ge(1-x)Snx films were measured by spectroscopic ellipsometry to extract their optical properties. The Sn contents of the films were 3.6%, 6.5%, and 8.4%, and all were fully strained to a Ge (001) substrate. Optical constants were collected from 0.39-4.116 eV, at temperatures between 78K and 475K. Resolution varied from 0.002 eV at low energies with high feature densities to 0.012 eV at high energies with low feature densities. Optical properties were extracted by modeling in J.A. Woollam’s WVASE software as three layers: a temperature-dependent Ge model from the bare wafer scans, a Ge(1-x)Snx model, and a Bruggeman effective medium approximation layer that blends the Ge(1-x)Snx model 50:50 with vacuum to account for surface roughness and any thin surface layers. WVASE .mat files are presented as tabulated and as general oscillator forms, along with plain text n and k files.



Files are organized by Sn content (3p6per files, for instance, are from the 3.6% Sn film), then by scan temperature, then by file type - GenOsc and tabulated files are for use with J.A. Woollam's WVASE software, while tab files are plain text.

Funding Agency: 
Air Force Office of Scientific Research, Office of Naval Research
Grant Number: 
FA9550-20-1-0188, FA9550-15-1-0352, N00014-17-1-2591