Local structural investigation of buried InAsxP1−x/InP interfaces

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Abstract
A local structural investigation has been carried out on the 10 Å InAsxP1−x layer in ad hoc grown InAsxP1−x/InP epitaxial multistructures deposited by low pressure metallorganic chemical vapor deposition by means of extended x‐ray absorption fine structure spectroscopy, high resolution transmission electron microscopy, and high resolution x‐ray diffraction analyses. The goal was to characterize the local structure of the unwanted, strained, interface layers of InAsxP1−x produced by the exposure of the InP surface to AsH3 as occurs during the growth of InP/In0.53Ga0.47As heterostructures optimized for photonics. High resolution x‐ray diffraction and high resolution transmission electron microscopy confirm the high crystalline perfection of the investigated interfaces. As K‐edge extended x‐ray absorption fine structure analysis shows, the first shell environment of As at these interfaces is similar to that found in bulk InAsxP1−x alloys of similar composition, as determined experimentally and by comparison with recent theories of bond lengths in semiconductor alloys. In particular we measure an As—In bond length which varies at most 0.02 Å with As concentration at the interface; this implies that epitaxy with InP is accompanied by local structural distortions, such as bond angle variations, which accommodate the nearly constant As—In bond length.