Evaluation of data storage layer thickness best fitted for digital data read-out procedure from hard x-ray optical memory

摘要

Paper is devoted to further evolution of the concept of ultra-high density hard x-ray storage media - a radically new x-ray-based optical data storage nanotechnology with terabit-scale digital data density per square centimeter of each storage layer of the memory disk. Forthcoming hard x-ray optical data read-out devices will use an ultra-high density information carrier named x-ray optical memory (X-ROM), which consists of crystalline wafer with the generated subsurface amorphous nanometer-size reflecting speckles of x-ray high-reflectivity material. X-ROM is designed for long-term archiving of the large volumes of information and digital data handling via read-out systems operating on x-ray wavelength optics. Digital data read-out procedure from X-ROM is performed via grazing-angle incident x-ray micro beam. X-ray-based optical data storage system detects data by measuring changes in x-ray micro beam intensity reflected from the various surface points of data storage media. Grazing-angle incident x-ray configuration allows the handling of data from very large surface area of X-ROM disk and, consequently, the data read-out speed is much faster than in optical data read-out systems. Aim of paper is detailed evaluation of storage data-layer's effective thickness best fitted for a digital data read-out procedure. Penetration depths of non-homogeneous x-ray wave fields inside crystalline substrate and amorphous speckles of X-ROM are investigated theoretically in case of grazing-angle incidence x-ray backscattering diffraction (GIXB) applied in specular beam suppression mode. It is possible to reduce the effective thickness of data storage layer to a value of less than a single-bit linear size i.e. to reduce effective thickness up to 10 nm, according to performed evaluations.