HOT-ELECTRON INDUCED NEGATIVE PHOTOCONDUCTIVITY IN NORMAL-INSB/GAAS WITH ABOVE GAP ILLUMINATION AT LOW-TEMPERATURE

The low temperature photoconductivity under pulsed illumination has been studied experimentally in n-InSb/GaAs heterostructures grown by metalorganic magnetron sputtering (MOMS). At photon energies slightly greater than the band gap of InSb (up to ≈ 0.4 eV), we observe the usual positive photoconductivity effect due to the increase in the density of carriers. However, illumination with photons of still higher energies (≥ 0.4 eV) leads to the coexistence of a positive and a slow negative photoconductivity. The latter, which increases with increasing photon energy and decreasing film thickness, is tentatively associated with diffusion of hot electrons to the interface and with a reduction of the electron mobility in the layer. © 1990.