<title>X-ray diffraction optics of the submicron surface layers</title>

Abstract

The scheme of x-ray diffraction on reflection for research oflayers structure of single crystals after various kinds of external treatment is used. On series of diffraction curves the profiles of distribution of deformations in thin subsurface areas of InSb and CdTe crystals irradiated by high-energy electrons and B ions are constructed.Given work demonstrates the opportunities of scew assymetric scheme of x-ray diffraction on reflection as in topographical, as in two crystal spectrometer scheme in research of structural changes in subsurface layers of various single crystal compaunds after ion and electron irradiation. MAIN RELATIONSAt present the use of semiconductor materials acquires practical significance. However, for creation on their bases qualitatively new devices of opto-and microelectronics the perfect crystals with defmite electrophysical properties are necessary. Therefore, further perfection of conventional technologies, as well as search of new methods as growth, as qualitative processing of surface of materials is of one of important tasks of modern semiconductor material science. In this connection, use for decision of these tasks x-ray diffraction methods, as highly informative nondestructive methods of control of degree ofperfection, acquires the significance.All greater interest is attracted the problem of interpretation of the x-ray diffraction curves from crystals with very thin (O.l-O.OOljim) disturbed layers, arising in processes of chemo-mechamcal treatment, ion implantation and dope, epitaxial growth, laser treatment etc.!19 The kind of diffraction curves is completely connected with structure varying on depth of disturbed layer. This connection appears difficult and decision of reverse problem comes across on serious difficulties.8 The given problem can be resolved if for nondestructive selective layer by layer analysis of structural changes in subsurface layers the scew assymetric diffraction on reflection scheme is used.17-19 The distinctive feature of given scheme is that the reflecting planes for which angle of diffraction () is less than angle of disorientation between incident and reflecting crystalographyc planes (w) are here chosen, i.e. O(i. Subsequent azimuthal scanning of sample arround diffraction vector in given scheme of diffraction provides the sliding on surface of incident beam in any range of angles and reflection of diffracted angle at large, close to ir/2 angles. It opens the new opportunities of layer by layer topography of subsurface layers of crystal, and also to avoid of ambiguity of solution of reverse taskdetermination of deformation profile in the subsurface layer on series of diffraction curves.Known methods of extreme asymmetric Bragg diffraction1-16 with minimum angle of incidence (o) admit the approximation e w (w -angle between incidence surface of crystal and reflecting planes, e-Bragg angle), or cD cr fFT,((Dcr -critical angle of total external reflection). The realization of such as above approximate equality of angles is not of greate difficulty in ca...

X-Ray Topography of the Subsurface Crystal Layers in the Skew Asymmetric Reflection Geometry

“…Application of a skew asymmetric reflection geometry of X-ray diffraction in crystal gives an opportunity to perform selective studies of structural changes in the subsurface layers of crystalline compounds [9][10][11][12][13][14][15][16][17][18][19][20] with sufficiently small depth step (0.01-0.1 µm). Figs.2-10 show specific examples of using a skew asymmetric reflection geometry of X-ray diffraction for various crystals: а) determination of quality of mechanochemical treatment of cdTe (Fig.2, Fig.3), ge (Fig.4), and Si ( Fig.5) surfaces; b) characterization of surface relief and morphology of InSb/InSb homoepitaxial systems (Fig.6) and CdHgTe/ cdTe epitaxial systems (Fig.7); c) determination of structural modifications of cdTe surface after laser irradiation (Fig.8), as well as structural changes after implantation of phosphorous ions into silicon (Fig.9).…”

“…To realize this condition is not a problem when synchrotron radiation is available. At the same time, for the characteristic radiation of X-ray tubes the values of angles ϕ 0~1 0 -3 can be achieved very easy [9][10][11][12][13][14][15][16][17][18][19][20]. Among possible diffraction planes (hkl) for the proposed diffraction geometry preference should be given to those for which the difference between the values of angles θ and ψ is insignificant, i.e.…”

“…This experimental scheme of X-ray diffraction opens up new opportunities for a layer by layer visualization of structural changes in the subsurface crystal layers, and also allows increasing the discrimination of strain types in the subsurface layers using a series of diffraction reflection curves [11][12][13][14][15][16][17][18][19][20].…”

“…Nowadays, there exist a great number of various X-ray methods for investigating thin subsurface layers of thickness less than 0.1µm [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. However, not all of them allow visualize structural changes in these layers.…”

“…Unlike X-ray topographic methods, X-ray diffraction techniques provide no information on the local distribution of defects in the crystal bulk and in thin subsurface crystal layers. Topographic methods give a direct image of many types of crystal defects and may be used to estimate crystal perfection with high strain sensitivity [9][10][11][12][13][14][15][16][17][18][19][20].…”