Very low loss waveguides formed by fluorine induced disordering ofGaInAs/GaInAsP quantum wells

摘要

Selective area intermixing of quantum well (QW) structures usingfluorine as a disordering impurity is demonstrated. Bandgap widenedridge waveguides have been fabricated using this process and theresultant waveguides had losses of between 8.5 dB cm-1 and0.6 dB cm-1. In purely thermally intermixed samples, thelowest loss measured is 18.5 dB cm-1 and, if an electricallyactive dopant was used as a disordering species, a propagation loss dueto free-carrier absorption of greater than 40 dB cm-1 isexpected. By implanting with fluorine to give a concentration of around1018 cm-3 and annealing at 700° C it ispossible to widen the QW structure by as much as 40 meV, while leavingthe unimplanted structure relatively unchanged. It has also been shownthat SiO₂, but not Si₃N₄, dielectriccaps can be used to provide protection during the annealing stage of theprocess