ELECTRON-TRANSFER BETWEEN 2 COUPLED QUANTUM-WELLS IN A RESONANT-TUNNELING DIODE STRUCTURE

Resonant tunneling effects between the quantum well of a double barrier heterostructure and the accumulation layer of the emitter region are investigated. Numerous singularities in the current-voltage characteristic of a GaAs/Al0.4Ga0.6As diode, such as a negative differential conductance effect with a current contrast of 15:1, have been found and analyzed by means of self-consistent calculations of conduction band profile and tunneling probabilities. At relatively low bias, charge transfer can be interpreted as direct or scattering-assisted transitions with optical phonon emission, by considering the anti-crossing of the ground states or the energy conservation rules. At higher voltages, very fast tunneling processes al the time scale of relaxation mechanisms (through the second level of the accumulation layer) were demonstrated. Such a hot electron transition with direct evidence of negative differential conductance effect involves a non expected build-up of the resonance as a function of the symmetry of confining potentials in terms of transmission probabilities.