Study of electron capture by quantum dots using deep-level transient spectroscopy

The electron emission from and capture by quantum dots in InGaAs/GaAs p-n h eterostructures were studied using deep-level transient spectroscopy in rel ation to the conditions of isochronous annealing with a switched-on or -off bias voltage (U-ra < 0 or U-ra = 0). The results indicate that, as a resul t of annealing with U-ra < 0, a dipole that consists of charge carriers loc alized in the quantum dots and the ionized lattice defects is formed. The e lectrostatic potential of this dipole reduces the barrier for the electron emission from and capture by a quantum dot. If the annealing is performed a t U-ra = 0, no dipole is formed and the band offset is controlled by the co nditions of heteroboundary formation during the structure growth. The depen dence of the barrier height on the filling-pulse duration was also observed ; this dependence is related to the manifestation of the Coulomb blockade f or the electron capture by the ground and excited states of a quantum dot. The structures with quantum dots studied were grown by gaseous-phase epitax y from metal-organic compounds using self-organization effects. (C) 2001 MA IK "Nauka/Interperiodica".