Gilgen, Rytz-Froidevaux, Salathé and Zysset have demonstrated an athermal, CW-laser annealing process which improves the luminescent efficiency of LPE AlGaAs 3-layer heterostructures by as much as 80%. Their investigation of the process has revealed several remarkable aspects. I explain these in terms of redistribution of defects grown into the original material and, in particular, elimination of vacancies and of interfacial mismatch stress by microsplit formation. GeGaAlAs is suggested as a new luminescent center. © 1983.