DECAY DYNAMICS IN DISORDERED-SYSTEMS - APPLICATION TO HEAVILY-DOPED SEMICONDUCTORS

We have calculated, quantitatively, the time decay of donor-acceptor p air luminescence in compensated semiconductors, incorporating the effe ct of the potential fluctuations which exist in such materials. We sho w that the often-reported stretched-exponential decay law can here be derived rigorously, but only to a very close approximation, and, moreo ver, only provided that there is an alternate, activated, decay path. We also show that in the absence of such an alternate path, the decay is slower. We thus conclude that the stretched-exponential ''law'' pro vides good empirical fitting, but has no fundamental significance.