Ultrafast-lifetime quantum wells with sharp exciton spectra

Sharp quantum-confined excitons in semi-insulating low-temperature-growth AlAs/GaAs quantum wells with 15 ps carrier lifetimes are demonstrated. High-quality well-barrier interfaces can be grown at low substrate temperatures and annealed up to temperatures of 700 °C, beyond which interface mixing broadens the exciton transitions. Electroabsorption from the quantum-confined Stark effect in as-grown modulators approaches 10 000 cm−1, which is comparable to traditional high-temperature growth quantum wells. The low-temperature growth quantum well structures eliminate the need for postgrowth processing, such as ion implantation for photorefractive quantum wells, ultrafast saturable absorption, or electro-optic sampling applications.