Characterization of strain in $Si_1_-_xGe_x$ films using multiple angle of incidence ellipsometry

Mukerjee, Subroto and Venkataraman, V (2000) Characterization of strain in $Si_1_-_xGe_x$ films using multiple angle of incidence ellipsometry. In: Applied Physics Letters, 77 (22). pp. 3529-3531.

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Abstract

In this letter we characterize strain in $Si_1_-_xGe_x$ based heterojunction bipolar transistors and modulation doped field effect transistors grown by rapid thermal chemical vapor deposition exploiting the phenomenon of strain-induced birefringence. The technique used is multiple angle of incidence ellipsometry at a wavelength of 670 nm to measure the ordinary and extraordinary refractive indices of the $Si_1_-_xGe_x$ films. We report measurements on thin fully strained films (with thicknesses less than the critical thickness) with Ge concentration varying from 9% to 40% with an accuracy of the order of 1 part in 104 and propose an empirical relation between the difference in the ordinary and extraordinary refractive indices (\delta n) and the Ge concentration (x) given by $\delta n(x) = 0.18x-0.12x^2$.

Item Type:	Journal Article
Publication:	Applied Physics Letters
Publisher:	American Institute of Physics
Additional Information:	Copyright for this article belongs to American Institute of Physics (AIP).
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	08 Apr 2005
Last Modified:	19 Sep 2010 04:18
URI:	http://eprints.iisc.ac.in/id/eprint/2993

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