Capacitance Anomaly in the Negative Differential Resistance Region of Resonant Tunneling Diodes

For In0.53Ga0.47As/AlAs resonant tunneling diodes, the peak structure in the capacitance-voltage (C-V) characteristics in the negative differential resistance (NDR) region was investigated. We experimentally reveal that the electron sheet density that is responsible for the capacitance peak is equal to half of that in the quantum well at the peak voltage. The derived electron sheet density in the quantum well at the peak current is 3.2×1011cm-2and the resulting electron lifetimes in the quantum well are 320 and 580 fs for 2.0- and 2.3-nm AlAs barriers.