Strain effects on resonant parameters in asymmetric In_1-xGa _xAs quantum dot molecules

We investigate theoretically the strain effects on resonant properties in asymmetric In_xGa_1-xAs vertically stacked coupled quantum dots. The strain can modify the resonant electric field and the energy splitting between the bonding and antibonding molecular states of electrons (holes) in quantum dot molecules. The strain reduces resonant electric fields for both electron and hole resonance. However, it is found that molecular bonding is enhanced (suppressed) for electron (hole) resonance when considering the strain. The reversal of electron and hole bonding characters is attributed to different strain components acting on their respective energy bands. Such strain difference also leads to different composition dependence of resonant electric fields for each electron or hole resonance.