Optical Absorption in Pure Single Crystal InSb at 298° and 78°K

The absorption spectra of single crystal homogeneous InSb were measured in the spectral range 5 to 10 microns at temperatures of 78°K and 298°K. Primary emphasis was placed on the precise determination of absorption coefficients less than 400 ${\mathrm{cm}}^{-1\mathrm{}}$. Absorption spectra were measured in many samples over the following range of impurity concentrations. Net impurity concentrations, expressed in atoms ${\mathrm{cm}}^{-3\mathrm{}}$, ranged from 5×${10}^{15}$ to 9.5×${10}^{16}$ in $p$-type samples, and from 2×${10}^{15}$ to 3×${10}^{17}$ in $n$-type samples, as determined from Hall coefficients measured at 78°K.