Ga1−xAlxAs-Ga1−yAlyAs-GaAs double-barrier structures

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Abstract
The effect on negative resistance of a small aluminum concentration in the outer GaAs layers of a GaAs‐Ga1−xAlxAs double‐barrier tunneling structure is calculated. The aluminum concentration can be chosen so that the alloy conduction‐band minimum is slightly below the energy of the resonant tunneling level of the GaAs central well region. Less voltage is then needed to raise the incoming electrons into the resonant energy level. The decreased voltage across the structure has several beneficial effects. The electron transmission coefficient through the barriers on resonance increases, the total applied voltage across the device is reduced, and the current through parasitic parallel resistances is reduced. Significant improvements in peak‐to‐valley ratios are predicted, the improvement being dependent on the parameters of the structure.