Photoresponse induced by Ge nanodots on SiO2/Si substrate

Ge nanodots, produced by solid phase crystallization of amorphous Ge layers deposited at room temperature on SiO2 thermally grown on a Si(100) surface, generate a photocurrent in the visible and ultraviolet range. The photocurrent signal was detected by measuring the current flowing through the sample under irradiation either in planar or in up-down geometry. In both cases the quantum efficiency of the bare SiO2/Si(100) substrate was dramatically enhanced up to a factor of 103. Current-voltage curves were acquired in the latter geometry, evidencing an increase in the short circuit current induced by the Ge nanodots presence.