Infrared Absorption inn-Type Aluminum Antimonide

Abstract

The optical absorption constants of tellurium and selenium doped $n$-type AlSb have been determined in the spectral region 0.7-38 microns at 300 and 78°K. A 4.3-micron band exists at 300°K for which the absorption constant varies linearly with electron concentration. This band may be explained by a 0.3-ev spin-orbit split off conduction band or alternatively by a multivalleyed conduction band with a central minimum 0.3 ev above the lowest minima. A transition from the highest valence bands to the lowest conduction level could account for the observed absorption starting at 1.33 ev. At wavelengths greater than 8-10 microns free carrier absorption exists with a ${\lambda }^2$ dependence and a calculated effective mass of 0.3 m. Lattice bands are present at 11.2, 13.5, 16.5, 22.9, 27.8, and 29.8 microns.