Calculation of carrier capture time of a quantum well in graded-index separate-confinement heterostructures

The electron capture time into the quantum well of a graded-index separate-confinement heterostructure laser has been calculated at 77 and 300 K. The results (at 77 K) show oscillations between several picoseconds and several tens of picoseconds with increasing quantum-well thickness, qualitatively similar to the behavior in simple separate-confinement structures. Quantitatively, the difference in capture times for optimal structures of each kind does not explain the lower threshold of the graded-index structure.