Oscillatory Photoconductivity in InSb

The oscillations in the low-temperature photoconductive spectral response of $p$-type InSb are found to be strongly dependent on electric field strength in both intrinsic and extrinsic photoconductivity. The oscillatory structure gradually disappears at electric fields higher the ∼20 V/cm. As a function of increasing temperature, the position of the minima of the oscillations shifts towards lower energies and the size of the oscillations decreases. A qualitative interpretation, consistent with all observations, shows that the primary reasons for oscillatory photoconductivity are: (a) the preferential momentum losses of carriers due to longitudinal optic phonon emission in the direction of the electrical potential gradient; (b) the fact that the steady-state distribution of carriers generated by photon absorption is drastically different from equilibrium.