A study of conduction-band L-states in GaSb through observations of the influence of uniaxial stress on its infrared free-carrier absorption

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Abstract
Measurements have been made of the optical absorption in n-type GaSb doped approximately 2.5*1017cm-3as a function of high (111) uniaxial stress. Specimens were held at temperatures of 18.5K and 79K and results obtained over the wavelength range 7-22 mu m for radiation polarized parallel or perpendicular to stress. Free-carrier absorption was found to dominate in the wavelength range investigated and although high stress caused large changes in its magnitude, the wavelength dependence lambdapwas independent of stress and polarization with p=2.7+or-0.2 at 18.5K and 3.0+or-0.2 at 79K. Important features of the observed absorption behaviour at 18.5K were a threshold stress below which there was no change, opposite changes for the two polarizations above the threshold, and saturation of the variation at high stress for radiation polarized perpendicular to stress.
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