X-ray physics applied to the study of nanostructured devices using compact radiation source

Abstract

X-radiation has been a powerful tool for analyzing the structure of materials at atomic scale. While many are fascinated with the perspectives offered by advanced synchrotron X-ray sources, the practical aspects of these perspectives in the actual and future state of nanotechnology remains little discussed. Nanotechnology, i.e. the capacity of controlling matter at atomic-molecular scales and manufacturing structures with dimensions of a few tens of nanometers, has provided a constant challenge for structural analysis via X-ray techniques. The great diversity of materials and methods derived from nanotechnology is generating a huge demand for time of analysis, much beyond of that can be supplied by synchrotron facilities worldwide. In optimizing nanostructured materials and devices processing methods, fast and easy-access techniques to control and characterization are required. Microscopy and spectroscopy techniques are very important in the actual scenery of nanotechnology, but they have intrinsic limitations that have justified the search for high-resolution techniques of structural analysis, such as those obtained by diffraction and/or scattering of X-rays.The usage of conventional X-ray sources, i.e. compact sources such as tubes and rotating anodes, represent a great challenge in the field of nanoscience. The relatively low radiation power of such sources restrains the type of nanostructured materials to be analyzed and also the accessible structural information. On the other hand, when an information is attained, it is of tremendous practical importance. It can guide the optimization and control of device processing, and with the advantage that can be set in a nearby place and to be full time available for such specific purposes. This is the major objective of this project, to set an experimental laboratory to exploit techniques for analyzing nanostructured devices using conventional X-ray sources. It was also one of the objectives of the project approved back in 1997 (FAPESP process 97/13757-8) when the Huber goniometer and the Philips X-ray generator that will be used in this project were purchased. Due to the starting of the Brazilian synchrotron source, also in 1997, the goniometer was transferred to a beamline where it gives rise to several works. Recently, it was brought back to the Institute of Physics at USP where it is waiting the approval of this project to be properly set in operational condition. With a few improvement in the equipaments, such as accurate X-ray detector at low counting rates, electronics for friendly step-motor control and data acquisition, crystals for triple axis measurements, and safety hutch, we will have the necessary conditions to: i) continue our investigation on growth and capping processes of quantum dots; ii) develope techniques for analyzing this type of system; iii) collaborate with other groups working on related fields, such as on nanostructured sol-gel films and epitaxial systems; and iv) teach pos-graduate courses and supervise master and PhD thesis on X-ray physics applied to nanotechnology. (AU)