Capacitance engineering for InP-based heterostructure barrier varactor

We investigate new schemes of InP-based heterostructure barrier varactors with the aim of enhancing the capacitance nonlinearity of the devices. Starting from a generic step-like InGaAs/InAlAs/AlAs single barrier heterostructure, planar-doped and buried InAs quantum-well barrier heterostructures were successfully fabricated. It is shown that both solutions lead to more efficient screening of electric field near equilibrium and hence to improvement in the capacitance-voltage ratios with values as high as /spl sim/7:1. Under bias, the capacitance modulation is governed by an escaping mechanism in contrast to the conventional depletion operation mode observed for conventional varactors.