Photoresistance of Si/Ge/Si structures with germanium quantum dots

An exponential decrease in the resistance of a Si/Ge/Si structure containin g germanium quantum dots with an increase in the band-to-band optical excit ation intensity is observed at 4.2 K. Two different exponential regions in the dependence of structure resistance on the optical excitation intensity are observed in elastically strained structures, but only one such region i s observed in unstrained structures. The experimental results obtained are explained within the model of the hopping conduction of nonequilibrium elec trons, which are localized at and between quantum dots in the strained stru ctures, but are localized only between quantum dots in the unstrained struc tures. (C) 2000 MAIK "Nauka/Interperiodica".