Infoscience

Conference paper

Laser generated (Al,Ga)As microstructures with high luminescence efficiency

New luminescence centers can be generated by irradiating AlxGa1-xAs structures with focused light from a CW Kr-ion laser operated at 647 nm. The luminescence centers are generated at a laser power density of 0.5 MW/cm2. Regions as small as 0.8 μm wide and 0.2 μm thick are generated. The new luminescence centers are characterized by a high photoluminescence efficiency at room temperature and an emission energy 90-140 meV below the band-to-band recombination. They are of permanent nature: No changes in the emission spectrum or in the efficiency could be observed, if processed samples are subjected to heating cycles of up to 420°C. Edge emitting LEDs have been prepared from laser processed (Al,Ga)As heterostructure material. In the laser processed regions the diodes exhibit a light yield within the new luminescence band which is more than quadrupled at low currents. The light output decreases to values below the band-to-band recombination at densities above 2.0 kA/cm2

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