Here are reminiscences of some of my interactions with Marshall Stoneham and my career in industry, and particularly of his timely support for my work; and with some illustration of the importance of keeping a firm grasp on basic science to help see the wood from the trees in evaluating new technologies. It is interesting to see that fundamental theory established several decades ago needs to be further developed with some quite radical change of viewpoint when it is applied to new technology; and it is ironic that the impetus for such development of fundamental theory can be technological and commercial, rather than purely academic.M Supplementary data files are available from stacks.iop.org/JPhysCM/18/S389 Nonradiative transitionsI first met Marshall in the 1970s. I was a post-doctoral fellow looking for a problem involving impurity or defect related deep levels in semiconductors. I was fortunate to get invited to attend a small meeting of the cognoscenti in the subject at Plessey Caswell, and Marshall was one of the prominent speakers. I am quite sure you can imagine the authority and eloquence with which he spoke on many aspects of defects and related deep levels. What most caught my attention was what he had to say on nonradiative multiphonon transitions [1]. He spoke with such aplomb, nay even insouciance, on such arcane matters as nonadiabaticity, along with promoting and accepting modes, that I was both intrigued and fascinated, if not somewhat overawed.

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To realize tensile strain on GaAs substrates, a novel structure consisting of athick non-pseudomorphic InAlAs grid layer and InGaAs-GaAs strained-layer superlattice dislocation filter is proposed. The combined structure is examined by photoluminescence, Nomarski etch-pit microscopy and double crystal x-ray diffraction and found to be effective in incorporating tensile strain in devices grown on the GaAs substrate.