Patent ID: 8226767
Filing Date: 2012-07-24
Classification: G01N

Abstract:
1. A method for quality control and selection of prime wafers in a rhombohedral, super-hetero epitaxial semiconductor material of a continuous epitaxial structure, said material comprising a substrate having a first crystal structure, and at least one epitaxial layer having a second crystal structure that differs from said first crystal structure, said method comprising a) using X-ray diffraction in which the combination of Omega (goniometer angle) and Chi (angle of [111] vector relative to the X-ray diffraction reference orientation) parameters, as a function of Theta (Bragg angle) and Beta (interplanar angle of alloy's {111} plane and selected non-perpendicular plane) are selected from the group consisting of (a) Chi=Beta, Omega=Theta; (b) Omega=Theta+Beta, Chi=0; and (c) Omega=Theta-Beta, Chi=0, in order to determine double position defects; b) wherein said X-ray diffraction method is applied where the correspondence of said first and second crystal structures are within the group consisting of (i)cubic on trigonal, (ii) trigonal on cubic, (iii) hexagonal on cubic, and (iv) hexagonal on trigonal (wherein trigonal and hexagonal refers to space, symmetry).