Redistribution of the quantum well density of states under the influence of an electric field

The effects of an applied electric field on the energy dependence of the density of states (DOS) in symmetric quantum wells are investigated. The density of states is calculated by the retarded Green function using the method of the logarithmic derivative of the wavefunctions. It is demonstrated that there exist discrete states as well as a continuum of states between the bottom of the quantum well and the conduction band offset. The continuum of states depends heavily upon the applied electric field and the quantum well itself. The importance of the redistributed density of states, in energy and position, is demonstrated by calculating the electron escape time from a biased quantum well and comparing the results with previously reported experimental results.