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 num erical model. The MQW structures with a Schottky emitter contact exhib it stepwise C-V characteristics, with constant jumping of the inverse capacitance and with the distance between steps increasing with applie d bias. The structures with a tunnelling emitter barrier show a strong variation of capacitance, starting from large values, corresponding t o the emitter barrier width at low bias, and saturating at low values, corresponding to the length of the MQW structure at high bias. These features of the C-V characteristics are associated with the re-chargin g of the quantum wells with applied voltage. in turn, the re-charging effects are closely related to the electron injection and transport pr operties of the MQW structures.