Accession Number : AD0445686

Title :   INFRARED ABSORPTION OF MAGNESIUM STANNIDE,

Corporate Author : AIR FORCE CAMBRIDGE RESEARCH LABS HANSCOM AFB MA

Personal Author(s) : Lipson, Herbert G. ; Kahan, Alfred

Report Date : 27 AUG 1963

Pagination or Media Count : 11

Abstract : Infrared transmission and reflection measurements have been made on n- and p-type semiconducting Mg2Sn single crystals of different impurity con centrations between 2 and 30 microns, at temperatures ranging from 15 to 296 K. At incident energies less than 0.22 eV, strong free-carrier absorption is present: with alpha as the absorption coefficient and lambda the wavelength, this may be expressed as alpha=c(lambda to the 3/2 power) at all temperatures where acoustical mode lattice scattering predominates. The absorption spectra due to other mechanisms has been analyzed after subtraction of the lambda to the 3/2 power free-carrier dependence. At energies of 0.22 eV and above, the rapid increase in absorption is attributed to the intrinsic edge. From the energy dependence of the absorption coefficient in the edge region, the mechanism of indirect transitions between the valence and conduction band can be established, with a phonon energy of 0.008 eV. A band in the 0.08 to 0.22 eV energy range present at all temperatures in n-type and above 196 K in p-type samples is interpreted in terms of transitions between two conduction band minima separated by 0.165 eV at 15 K. (Author)

Descriptors :   (*MAGNESIUM COMPOUNDS, ABSORPTION SPECTRA), (*TIN COMPOUNDS, ABSORPTION SPECTRA), (*INFRARED RADIATION, ABSORPTION), (*SINGLE CRYSTALS, WAVE PROPAGATION), ENERGY, INFRARED OPTICAL MATERIALS, SEMICONDUCTORS, ELECTROMAGNETIC WAVE REFLECTIONS, BAND SPECTRA, TEMPERATURE, CRYSTAL LATTICES, VIBRATION, SELECTION RULES(PHYSICS), PHONONS.

Distribution Statement : APPROVED FOR PUBLIC RELEASE