Abstract
Coherent x-ray diffractive imaging is a nondestructive technique that extracts three-dimensional electron density and strain maps from materials with nanometer resolution. It has been utilized for materials in a range of applications, and has significant potential for imaging buried nanostructures in functional devices. Here, we show that coherent x-ray diffractive imaging is able to bring new understanding to a lithography-based nanofabrication process for engineering the optical properties of semiconducting GaAs1-yNy on a GaAs substrate. This technique allows us to test the process reliability and the manufactured patterns quality. We demonstrate that regular and sharp geometrical structures can be produced on a few-micron scale, and that the strain distribution is uniform even for highly strained sub-microscopic objects. This nondestructive study would not be possible using conventional microscopy techniques. Our results pave the way for tailoring the optical properties of emitters with nanometric precision for nanophotonics and quantum technology applications.
Highlights
Coherent x-ray diffractive imaging is a nondestructive technique that extracts threedimensional electron density and strain maps from materials with nanometer resolution
We show that good quality 3D electron density and strain maps can be extracted by Bragg CDI (BCDI) in an even more challenging case, where the GaAs0.991N0.009 planar structures under investigation are directly grown on the substrate, and not supported by amorphous oxide buffer layers
The problem of the scattering background from the substrate tail and along the truncation rod, which often affects similar experiments on highly strained epitaxial systems[26], has been dealt with by choosing N concentrations high enough to obtain a sufficient separation of the GaAs1−yNy peak from the substrate one for the [004] reflection, limiting in this way the contribution of the background on the signal diffracted from the sample
Summary
Coherent x-ray diffractive imaging is a nondestructive technique that extracts threedimensional electron density and strain maps from materials with nanometer resolution. High-optical efficiency can be obtained from quantum dots/wires spontaneously formed via self-assembly in highly strained heterostructures (“bottom-up” methods)[2], losing control in the spatial arrangement of the self-assembled structures. This limits the freedom of modulating the in-plane optical properties, which is crucial in the fabrication of photonic devices[3]. By allowing H incorporation in selected regions of the sample, it is possible to achieve a spatially tailored modulation of the band-gap energy as well as of the lattice parameter in the growth plane[4] This can be done by deposition of masks, which impede H diffusion in defined regions of the crystal[7] (as sketched, b). The spatial resolution of optical imaging (micro-PL, micro-Raman) is restricted by the diffraction limit of
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
