The Infrared Absorption Characteristics of Thermiated Germanium

The infrared absorption spectrum of thermiated germanium has been obtained. It is shown that this material in addition to its greatly changed electrical properties becomes strongly absorbing in the infrared. A 48-hour anneal in air at 500°C restores the infrared transmission to that identical with the untreated control sample. The absorption spectrum for chemically $P$-doped germanium has been obtained and the absorption cross section for the $P$-doped material compared with that of thermium.