Experimental dependence of resonant tunnel diode current on accumulation layer band profiles

Accurate predictive modeling and control of the negative differential conductance region of resonant tunnel diodes are important for their use in microwave circuit applications. Present ballistic transport models give much smaller currents in the negative differential conductance region than are measured for GaAs/AlAs devices. While an accumulation of charge in the cathode spacer just outside the barrier is necessary to produce a voltage drop across the structure, these models neglect the themialization of charge into this layer and its contribution to the current. We demonstrate the dependence of resonant tunnel diode characteristics on spacer accumulation layer band profiles by comparing a control sample with a sample which has an InGaAs "prewell" in the cathode spacer layer. The prewell sample has a relative valley or excess current that is reduced by 38 percent, on average, compared to the control sample.