Capacitance analysis for AlGaAs/GaAs and InAlAs/InGaAs heterostructure barrier varactor diodes

By self-consistently solving Schrodinger and Poissons equations, we have investigated the capacitances of AlGaAs/GaAs and InAlAs/InGaAs heterostructure barrier varactors. When compared with semiclassical particle model, quantum mechanics show that the maximal capacitance of the varactor is saturated when the spacer and barrier are thin. When the spacer and barrier are very thick, both the quantum mechanics and semiconductor particle approach result in the same conclusion, namely, the maximal capacitance is inversely proportional to the sum of the spacer and barrier thicknesses. We have also shown that the maximal capacitance increases for high carrier effective mass. (C) 1998 American Institute of Physics. [S0021-8979(98)08403-5].