APPLICATIONS OF NEUTRAL IMPURITY DISORDERING IN FABRICATING LOW-LOSS OPTICAL WAVE-GUIDES AND INTEGRATED WAVE-GUIDE DEVICES

Novel applications of impurity-induced disordering (IID) in semiconductor integrated optoelectronics are discussed and some requirements of the IID process are quantified. The effect of boron and fluorine as disordering species, in both GaAs/AlGaAs and GaInAs/AlGaInAs, has been studied. Because boron and fluorine are not active dopants at room temperature, low-loss high-resistivity waveguides can be formed. In the GaAs/AlGaAs system fluorine has been found to produce larger changes than boron for similar annealing conditions. Fluorine-disordered multiple quantum well waveguide structures exhibited blue shifts of up to 100 meV in the absorption edge (representing complete disordering). The absorption coefficient in partially disordered structures at near-band-edge wavelengths was as low as 4.7 dB cm-1. This absorption edge shift was accompanied by substantial changes, (> 1%) in the refractive index. Boron- and fluorine-induced disordering of GaInAs/AlGaInAs quantum well structures lattice-matched to InP has also been investigated. Only small blue shifts in the exciton peak, ascribed to implantation damage, were observed in boron-implanted samples, but blue shifts of over 40 meV (again representing complete disordering) were observed in the fluorine-implanted samples.