抄録
The concentration dependence of far-infrared absorption spectra of antimony-doped germanium with 6×1014 to 7×1016 cm−3, has been investigated in the wavelength range of 100 μm to 1 mm. In the excitation spectra, a higher energy line broadens faster with impurity concentration that a lower one, and disappears. In addition, the excitation lines shift slightly their position to lower energies and broaden in the low energy side with increasing concentration. Above 5×1015 cm−3, background absorption appears newly as a curve of gradual descent from the ionization limit toward low energies, and increases rapidly with concentration. This absorption spreads over the whole spectral range at 7×1016 cm−3, which would be responsible to the bolometric action. A qualitative discussion of the concentration effects is given.
For sample having a small thickness (≈100 μm), the doublet structure of the excitation spectra was observed to change by surface treatment.
