Local structural investigation of buried InAsxP1−x/InP interfaces

Abstract

A local structural investigation has been carried out on the 10 A InAsXP1-, layer in ad hoc grown InAsXP1 -,/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 InAs,P, --x produced by the exposure of the InP surface to AsHs as occurs during the growth of InP/Ino,ssGa0.47As heterostructures optimized for photon&. 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-, 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 ,& 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.

Tetragonal-strain-induced local structural modifications inInAsxP1−x/InPPascarelli1, Boscherini2, Lamberti3 et al. 1997Phys. Rev. BSelf Cite453220View full textAdd to dashboardCite

“…9 First-shell mean-square relative displacement values are similar to those found for the bulk alloys. This finding is in agreement with similar results on the In-As bond in InAs x P 1Ϫx strained layers 8,10 and in other systems of epitaxial layers of semiconductors. 18 Bond-angle fluctuations could be effectively estimated only for samples H 6 and H 7 , and are similar to those found for the unstrained samples.…”

“…Moreover, a full MS analysis of the XAFS spectra was performed to obtain a reliable structural picture beyond the first shell on these strained semiconductor superlattices. The present results significantly expand and complete our previously published investigation, 10 which was performed on fewer samples and was limited to the first coordination shell. The results discussed in this paper have been previously presented in a preliminary format.…”

“…14-16͒ and III-V-based systems. 10,[17][18][19] However, variations of first-shell bond lengths due exclusively to tetragonal strain have been measured in some strained epitaxial films of III-V semiconductors. [6][7][8][9]12 We have verified that, in all cases, experimental determinations of first-shell bond lengths agree very well with the predictions of our model, which therefore places these results within a clear interpretative framework.…”

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] This paper reports a x-ray-absorption finestructure ͑XAFS͒ investigation of the first three coordination shells around As in (InAs x P 1Ϫx /InP) N strained-layer superlattices and in unstrained bulk samples of similar composition for a wide As concentration range.…”

Unit cell of strained GeSi

“…In some cases, the strain has been found to have remarkable effects on bond lengths, 2,3 while others have found little or no effect. [4][5][6][7][8] Others yet have reported the counterintuitive result that bonds actually elongate in layers under compression. 9 In order to resolve the issue of bond-length strain, we have performed high-resolution polarization-dependent extended x-ray-absorption fine-structure measurements on strained and well characterized Ge x Si 1Ϫx ͑xϭ0.216 and 0.219͒ layers grown on Si͑001͒.…”