Thermal-anneal wavelength modification of multiple-well p-n AlxGa1−x As-GaAs quantum-well lasers

Data are presented showing that ordinary thermal annealing can be used to modify GaAs square wells into rounded AlxGa1−xAs quantum wells and shift the continuous 300-K laser operation of a p-n multiple-well AlxGa1−xAs–GaAs heterostructure laser to higher energy. Transmission electron microscopy is used to show that thermal annealing at 900 °C for 10-h changes, for example, well sizes from 85 to 105 Å and coupling barriers from 95 to 75 Å, which results in a change of laser photon energy of Δℏω∼50 meV. Bandfilling is minimal in multiple quantum-well lasers, thus making thermal annealing a useful method to ‘‘tune’’ a continuous 300-K quantum-well laser to shorter wavelength as shown here. These thermal annealing experiments indicate that the Al-Ga interdiffusion coefficient at a heterointerface is D(900)∼10−18 cm2/s.