Selective thermal interdiffusion using patterned SiO2 masks: An alternative approach to buried CdTe/CdMgTe quantum wires

Abstract

Buried CdTe/CdMgTe quantum wires with a lateral confinement potential of about 290 meV have been realized. Using electron beam lithography, SiO2 stripes are defined on a single quantum well sample and a subsequent 2 h annealing step in a Zn atmosphere results in a surprisingly strong interdiffusion between Cd and Mg atoms under the capped areas, causing a lateral modulation of the band gap. We obtain, e.g., for a nominal wire width of 100 nm, a lateral subband splitting of more than 8 meV, while the extension of the squared exciton wave function of the ground state is reduced to about 20 nm due to the error function-like potential shape.