Optical absorption below the absorption edge in Hg1−xCdxTe

The optical absorption below the absorption edge in x=0.2 and x=0.3 Hg1−xCdxTe alloys has been investigated. In p-type alloys of both compositions and at wavelengths equivalent to approximately 0.75 Eg to 20 μm, the measured optical absorption cross sections at 90 K were close to the intervalence cross sections calculated using first-order Kane k⋅p theory with a bandstructure parameter P of 8.4×10−8 eV cm and a heavy hole mass of 0.5 m. For Hg0.8Cd0.2Te the absorption cross sections were close to 1.8×10−15 cm2 for wavelengths between 15 and 20 μm. For Hg0.7Cd0.3Te , the absorption cross sections increased from approximately 1×10−15 cm2 at 5 μm to about 3×10−15 cm2 at 20 μm. At higher temperatures the intervalence absorption cross sections decreased; in addition, an intraband contribution to the total hole absorption cross section was observed.