Capacitance-voltage characteristics of multiple-quantum-well semiconductor heterostructures

The capacitance-voltage (C-V) characteristics of multiple-quantum-well (MQW) semiconductor heterostructures are studied using a proposed numerical model. The MQW structures with a Schottky emitter contact exhibit stepwise C-V characteristics, with constant jumping of the inverse capacitance and with the distance between steps increasing with applied bias. The structures with a tunnelling emitter barrier show a strong variation of capacitance, starting from large values, corresponding to the emitter barrier width at low bias, and saturating at low values, corresponding to the length of the NQW structure at high bias. These features of the C-V characteristics are associated with the re-charging of the quantum wells with applied voltage. In turn, the re-charging effects are closely related to the electron injection and transport properties of the MQW structures.