Set-up and evaluation of a mid-infrared reflectometer and investigation of the optical properties of doped tin telluride

摘要

A system comprised of a Bomem interferometer and a LT3-110 Heli-Tran cryostatwas set up to measure the reflectance of materials in the mid-infrared spectral region.Several tests were conducted to ensure the consistency and reliability of the system. Siliconand Chromium, two materials with well known optical properties were measured totest the accuracy of the system, and the results were found to be in good agreement withthe literature.Reflectance measurements on pure SnTe and several Pb and Mn-doped alloys werecarried out. These materials were chosen because they exhibit a strong plasma edge inthe mid infrared region. The optical conductivity and several related optical parameterswere calculated from the measured reflectance. Very low temperature measurementswere carried out in the far-infrared on Sn9SMn2Te, and the results are indicative of a spinglass phase at 0.8 K.Resistivity measurements were made at room temperature. The resistivity valueswere found, as expected, to decrease with increasing carrier concentration and to increasewith increasing manganese concentration.