Neutral Impurity Disordering of Quantum Well Waveguide Devices

Abstract

The neutral impurities boron and fluorine have been studied as species for impurity induced disordering. In the GaAs/AlGaAs system fluorine disordered multiple quantum well waveguide structures exhibited blue shifts of up to 100 meV in the absorption edge (representing complete disordering) accompanied by substantial changes, > 1%, in the refractive index. The absorption coefficient in partially disordered structures at near band-edge wavelengths was as low as 4.7 dB cm^-1. Integrated extended cavity lasers have been fabricated with low losses (19 ± 8.4dB cm^-1) in the passive waveguide. Disordering of GaInAs/AlGaInAs and GaInAs/GaInAsP quantum well structures lattice matched to InP has also been investigated. The temperature stability of as-grown phosphorus-quaternary material is poor, with blue shifts of the exciton peak occurring at temperatures greater than 500°C, but the aluminium-quaternary is stable to at least 650°C. Large blue shifts (up to 90 meV for phosphorus quaternary and 45 meV for aluminium quaternary samples) were observed in the fluorine-implanted samples. The estimated loss in fluorine-disordered phosphorus quaternary samples is typically around 8 dB cm⁻¹.