Band-gap blue shift by impurity-free vacancy diffusion in 1.5-μm-strained InGaAsP/InP multiple quantum-well laser structure

The effects of defect-enhanced, impurity-free, quantum-well (QW)-barrier compositional intermixing caused by the SiO2 cap annealing at 750 °C of a 1.5-μm InGaAsP/InP multiple quantum-well (MQW) laser structure have been studied by photoluminescence (PL). A substantial band-gap blue shift, as much as 112 nm (∼66 meV), was found in the structure and the value of the shift can be controlled by the anneal time. The amount of the shift does not depend on the thickness of the SiO2 cap layer. Ridge-waveguide lasers were fabricated on the different areas of the wafer, with and without a SiO2 cap during a 60 s anneal. The lasing wavelength of the laser produced with the SiO2 cap has a 78 nm blue shift over that of the laser without the SiO2 cap.