On the Nature of Oscillations in Impurity Photoconductivity Spectra of Ge

A theoretical analysis is given which considers the strong dependence of lifetime on the carrier energy, the impurity scattering, and the very short relaxation time τ op of the “hot” photocarriers due to optical phonons. The carrier energy is always smaller than the optical phonon energy and jumps from this value to nearly zero if the photon energy minus carrier ionizationsenergy is increased from just below to just above a multiple of the optical phonon energy. The main assumption made is that the lifetime of the carriers in this energy interval is solely determined by the relaxation time τ ac due to the acoustic phonons; the relaxation time with the equilibrium carriers τ re and the lifetime rr of “cold” carriers being much greater. The relative depth η of the oscillations is calculated and is in good agreement with experiments on Ga‐doped p‐type germanium at 7 °K.