Theoretical studies of dark current of quantum dots

A time evolution method is used to compute the electron escape time and dark current of a quantum dot under electric field. We found that for quantum dots with just one bound state, the ground state wave function can be well described by the product of a 2D confined wave function in the x,y plane and a 1D confined wave function in the z direction with an effective quantum well potential. A comparison of phase-shift analysis and the full time-dependent calculation is presented. Good agreement between the two in the large time scale is found, but discrepancy exists in the small time scale. Our study shows that the electron escape rate (which determines dark current) of quantum dots is much lower than that of quantum wells with the same bound-to-continuum transition energy.