QUANTUM-MECHANICAL VERSUS SEMICLASSICAL CAPTURE AND TRANSPORT-PROPERTIES IN QUANTUM-WELL LASER STRUCTURES

We have studied experimentally and modelled theoretically the capture properties and transport mechanisms of electrons and holes in laser structures. We describe first the extreme case where the barrier thickness is very large: then semiclassical drift-diffusion equations may be applied and quantum-mechanical effects at the edge of the well are negligible. A second extreme case occurs when the barrier is narrow enough for quantum mechanics to apply fully. There, strong variations of the capture time with the well width are expected and observed. In real laser structures, dimensions are such that we are in an intermediate case and both aspects have to be taken into account. We give some typical values for diffusion/capture mechanism induced delay times in such a case.