Quantum Confined Stark Shift and Ground State Optical Transition Rat in  Laterally Biased InAs/GaAs Quantum Dots
Date of this Version5-27-2009
Authors are grateful to Prof. T. B. Boykin (University of Alabama, Huntsville, AL) for useful discussions about the calculation of the transition rate. This work has been carried out in part at the Jet Propulsion Laboratory. California Institute of Technology, under a contract with the National Aeronautics and Space Administrator. Computational resources on nanoHUB.org funded by the National Science Foundationhave been extensively used in this work. Muhammad Usman is funded through Fulbright USAID (Grant ID # 15054783
The atomistic tight binding simulator NEMO 3-D has previously been validated against the experimental data for quantum dots, wells, and wires in the InGaAlAs and SiGe material systems. Here, we demonstrate our new capability to compute optical matrix elements and transition strengths in tight binding. Systematic multi-million atom electronic structure calculations explore the quantum confined stark shift and the ground state optical transition rate for an electric field in the lateral  direction. The simulations treat the strain in a ~15 million atom system and the electronic structure in a subset of ~9 million atoms. The effects of the long range strain, the optical polarization anisotropy, the interface roughness, and the nondegeneracy of the p-states which are missing in continuum methods like effective mass approximation or k•p are included. A significant red shift in the emission spectra due to an applied inplane electric field indicating a strong quantum confined stark effect (QSCE) is observed. The ground state optical transition rate rapidly decreases with the increasing electric field magnitude due to reduced spatial overlap of ground electron and hole states.
Stark effect, Strain, Quantum Dot, lateral field, transition rate