MONTE-CARLO ANALYSIS OF THE CARRIER RELAXATION PROCESSES IN LINEAR-GRINSCH AND PARABOLIC-GRINSCH QUANTUM-WELL LASER STRUCTURES

The carrier relaxation process is widely acknowledged to have a strong bearing on the modulation limit of quantum well lasers. As a first an d crucial step toward achieving a better understanding of this phenome non, we have developed a numerical technique to study such processes i n graded-index separate confinement heterostructure quantum well laser structures having an arbitrary grading profile. We base our approach on ensemble Mote Carlo stimulation of the carrier transport in the 3-D graded-index region and in the 2-D quantum well. We also introduce a technique to handle the carrier capture and re-emission processes with in the Monte Carlo method. The results obtained from our calculations for a number of structures with quantum well sizes 50-100 angstrom ind icate that the overall carrier capture time is about 5-7.5 ps under lo w injection condition for the linearly graded structures, and signific antly longer for the parabolically graded structures. On the other han d, the carrier capture efficiency is found to be higher for the parabo lic graded-index structures. We also compare our calculations to publi shed experiments and find good agreement.