There are more than a dozen different methods of diagnostic and control of the structural purity of materials which are used in modern micro- and optoelectronics. Each of them has their own strong and weak points, range and fields of use. Usually a couple of different methods are used in research together. The advantage of using x-ray methods against optical (in solving the problem of distorted crystal) is that interferention of coherent beams is not on artificial diffraction lattice but on crystal lattice of the researching object. It permits us to expand researching ranges of crystal structures distortions. The privilege of x-ray methods (like x-ray interferometry and diffractometry) is that they are nondestructive, noncontact, fast, do not require expensive equipment, and are highly sensitive. Unique information about deformation locations and electronic density as a function of width (from a few monolayers) can be determined from their use.