Dynamical diffraction imaging of voids in nearly perfect silicon

Abstract

X-ray diffraction topographs of extremely pure and perfect silicon single crystals are made using low-energy undulator radiation from a positron storage ring. Typical defect images observed are rather large round images having a black-white contrast and a diameter of about 40 µm. Applying the dynamical theory of x-ray diffraction, the defect contrast is explained by tensile strain in the lattice around voids close to the exit surface. This discovery of void-like microdefects explains, at least in part, the reduced density of the crystal intended to be used for a redefinition of the unit of mass, the kilogram.

Dynamical X-ray diffraction imaging of voids in dislocation-free high-purity germanium single crystals

“…Furthermore, it was possible to confirm the observations of Deslattes et al (1999) and Tuomi et al (2001) on nearly perfect Si crystals. They were not able to show that the observed dynamical diffraction patterns are in fact caused by voids, which we can support with this work.…”

“…Both Ge and Si single crystals have been grown dislocation free for decades (Dash, 1959;Tweet, 1958). Comparable investigations are reported for nearly perfect silicon crystals by Deslattes et al (1999) and Tuomi et al (2001). However, HPGe has specific material properties allowing one to conclude without any doubt that the localized tensile strain fields detected by X-ray topography are in fact vacancy clusters in the form of voids.…”

Synchrotron X-ray topographic study of dislocations and stacking faults in InAs

“…in this case of arsenic, similar to the well-studied GaAs precipitation [14,15]. According to the dynamical theory of X-ray diffraction the precipitates seen in the topographs are close to the surface [12,13]. …”

“…The black and white contrast of such dots, one of which is marked with P in the left enlargement suggests the presence of a precipitate or a void. Because the contrast of the dots is black on the positive side of theg vector, the black-white dots originate from precipitates that compress the surrounding lattice [12,13]. Precipitates in bulk III-V semiconductors are commonly predicted to consist of the group V elements, i.e.…”

Highly Efficient Oval Hollow Mode Operation in a Laser-Diode-Pumped Microchip Solid-State Laser

“…Large-area transmission XT was made with synchrotron radiation at the BW1 beamline of the HASYLAB-DESY in Hamburg [16]. The undulator spectrum was optimized for the third harmonic at 10.5 keV and further conditioned with two flat gold-coated mirrors.…”