Separation of the e 1 and E 1 Interband Transitions near 2 eV in Germanium by Thermoabsorption

By thermoabsorption of Ge thin films (thicknesses 300, 500, and 520 Å, modulation frequency 12.5 Hz, modulation depth δ T ≤ 4 K) the interband transitions e 1 and E 1 in the spectral range near 2 eV are investigated including the transitions with spin–orbit splitting. It is possible to separate these transitions on account of their significantly different temperature dependences: d e 1 /d T = −(5.47±0.02) × 10 −4 eV/K and d E 1 /d T = −(3.89±0.02) ×× 10 −4 eV/K. The spectral shift divergence overcompensates the Lorentz broadening of the peaks so that their resolubility becomes better at higher mean temperatures. The energies for the transitions extrapolated to 295 K and corrected as to give bulk results are e 1 = 2.107 eV, e 1 + Δ   1 *= 2.294 eV, E 1 = 2.134 eV, and E 1 + Δ 1 = 2.314 eV.