  Electronic states and transport phenomena in semiconductor quantum dots are
studied theoretically. Taking account of the electron-electron Coulomb
interaction by the exact diagonalization method, the ground state and low-lying
excited states are calculated as functions of magnetic field. Using the
obtained many-body states, we discuss the temperature dependence of the
conductance peaks in the Coulomb oscillation. In the Coulomb blockade region,
elastic and inelastic cotunneling currents are evaluated under finite bias
voltages. The cotunneling conductance is markedly enhanced by the Kondo effect.
In coupled quantum dots, molecular orbitals and electronic correlation
influence the transport properties.
