In_(0.75)Ga_(0.25)As on GaAs submicron rings and their application for coherent nanoelectronic devices

Electron-phase modulation in magnetic and electric fields will be presented in In_(0.75)Ga_(0.25)As Aharonov-Bohm (AB) rings. The zero Schottky barrier of this material made it possible to nanofabricate devices with radii down to below 200 nm without carrier depletion. We shall present a fabrication scheme based on wet and dry etching that yielded excellent reproducibility, very high contrast of the oscillations and good electrical gating. The operation of these structures is compatible with closed-cycle refrigeration and suggests that this process can yield coherent electronic circuits that do not require cryogenic liquids. The InGaAs/AlInAs heterostructure was grown by MBE on a GaAs substrate [1], and in light of the large effective g-factor and the absence of the Schottky barrier is a material system of interest for the investigation of spin-related effects [2-4]} and the realization of hybrid superconductor/semiconductor devices [5].