Capture of photoexcited carriers by a Grinsch structure

Abstract Capture of photoexcited carriers in different laser structures is investigated by subpicosecond luminescence spectroscopy. The capture time, from 20 K to 300 K, is monitored by the decay of the luminescence of the confinement layers. It is found to range between 2 and 10 ps both for linear and parabolic grading, and to be much longer in non graded structures. The improvement of the capture in the case of graded structures is due to the quasi-electric field experienced by the carriers, and might allow the devices to run at higher frequencies.