20 December 1989 Real Time Crystal Axis Measurements Of Semiconductor Materials
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Abstract
Since 1912 X-ray diffraction has been the principal method for determining the crystal axis orientation of materials. This test is generally time consuming and must be done in a shielded location. A new real time method has been developed using a rapidly scanned laser beam to analyze the surface morphology of the crystal. By relating the minute facets in the surface to the underlying lattice structure, the crystal axis orientation can be quantitatively determined. The laser beam rapidly rotates about the axis of the instrument projecting a narrow beam at a small point on the surface of the crystal. This scan illuminates the crystal from all azimuth angles while the angle of incidence is varied in successive incre-ments. The laser light reflected from the facets is detected by a centrally located sensor and correlated with a precise clock signal to determine its angular position. The accumulated data is then processed by appropriate algorithms to determine the crystal axis orientation. Then with the aid of individual solid geometry algo-rithms, the deviation of the crystal axis is calculated. This is accomplished in one second and the results are displayed on the monitor in degrees and tenths of a degree. The laser scanner is fully controlled by a computer which is also used to reduce the raw data. The data display is presented on the monitor screen in sufficient detail to determine subtle differences in crystal structure and orientation. Measurements have been made on face centered cubic single crystals of semiconductor materials such as gallium arsenide, cadmium telluride and silicon in 1,0,0; 1,1,0; and 1,1,1 orientations.
© (1989) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Sidney Weiser, Sidney Weiser, } "Real Time Crystal Axis Measurements Of Semiconductor Materials", Proc. SPIE 1164, Surface Characterization and Testing II, (20 December 1989); doi: 10.1117/12.962819; https://doi.org/10.1117/12.962819
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