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Title: Free-Space Time-Domain Method for Measuring Thin Film Dielectric Properties

Patent ·
OSTI ID:833454

A non-contact method for determining the index of refraction or dielectric constant of a thin film on a substrate at a desired frequency in the GHz to THz range having a corresponding wavelength larger than the thickness of the thin film (which may be only a few microns). The method comprises impinging the desired-frequency beam in free space upon the thin film on the substrate and measuring the measured phase change and the measured field reflectance from the reflected beam for a plurality of incident angles over a range of angles that includes the Brewster's angle for the thin film. The index of refraction for the thin film is determined by applying Fresnel equations to iteratively calculate a calculated phase change and a calculated field reflectance at each of the plurality of incident angles, and selecting the index of refraction that provides the best mathematical curve fit with both the dataset of measured phase changes and the dataset of measured field reflectances for each incident angle. The dielectric constant for the thin film can be calculated as the index of refraction squared.

Research Organization:
Rensselaer Polytechnic Institute, Troy, NY (US)
Sponsoring Organization:
USDOE Office of Environmental Management (EM) (US)
Assignee:
DOEEMSP
Patent Number(s):
6,057,928
Application Number:
R&D Project: EMSP 65004; 09/333,596; TRN: US200430%%1490
OSTI ID:
833454
Resource Relation:
Other Information: PBD: 2 May 2000
Country of Publication:
United States
Language:
English

References (4)

A reliable method for extraction of material parameters in terahertz time-domain spectroscopy journal January 1996
Coherent broadband microwave spectroscopy using picosecond optoelectronic antennas journal January 1989
Optoelectronic on-chip characterization of ultrafast electric devices: Measurement techniques and applications journal January 1996
Far-infrared time-domain spectroscopy with terahertz beams of dielectrics and semiconductors journal January 1990