Emission rates for electron tunneling from InAs quantum dots to GaAs substrate

Artikel i vetenskaplig tidskrift, 2004

Tunneling emission rates of electrons from InAs quantum dots (QD) in a GaAs matrix depletion region have been calculated for application in the analysis of experimental data from deep-level transient spectroscopy (DLTS). The hybridization among metastable states localized in the InAs QD and continuum states in the GaAs substrate in the DLTS measurement is evaluated from the local densities of states. Two physical quantities have been calculated, the broadening of the metastable state localized in the InAs QD, i.e., the charge-transfer rates from the quantum dot to the substrate, and the corresponding hybridization coefficients. The metastable state is broadened significantly only when the bias is large enough, whereas the hybridization coefficients increase almost linearly with the bias. The effects of the direct Coulomb interactions and exchange energies among electrons initially confined in the QD have been included and found to be very significant. Increasing the number of electrons initially confined in the QD from 1 to 4, the charge-transfer rates increase by a factor of 1.8.