Pulsed-laser irradiation quantum well intermixing process in GaInAs/GaInAsP laser structures

We report the development and characterization of a postgrowth bandgap modi fication technique of GaInAs/GaInAsP laser structures utilizing a Q-switche d Nd:YAG laser with a pulse length of similar to 8 ns and repetition rate o f 10 Hz. Quantum well intermixing effect of the samples irradiated under pu lsed energy densities of 2.8, 3.5 and 3.9 mJ mm(-2) at different exposure t imes was studied. A maximum bandgap shift of up to 112 meV has been observe d from sample exposed to 3.9 mJ (-2) for 5 min after subsequent annealing i n a rapid thermal processor at 625 degrees C for 120 s. A spectrum broadeni ng of 3 mm meV, relative to the as-grown sample, was obtained from intermix ed sample exposed to 2.8 mJ mm(-2) for 1 min indicating that the quality of the material remains high. A differential bandgap shift of 60 meV has been obtained between a gold-masked region and laser-irradiated region. Lasers with bandgap tuned to 82 nm relative to the as-grown lasers have been fabri cated using this technique. (C) 2000 Elsevier Science B.V. All rights reser ved.