Grazing incidence synchrotron x-ray diffraction method for analyzing thin films

A method using synchrotron radiation parallel beam x-ray optics with a small incidence angle a on the specimen and 20-detector scanning is described for depth profiling analysis of thin films. The instrumentation is the same as used for 0:2© synchrotron parallel beam powder diffractometry, except that the specimen is uncoupled from the detector. There is no profile distortion. Below the critical angle for total reflection ac, the top tens of Angstroms are sampled. Depth profiling is controlled to a few Angstroms using a small a and 0.005° steps. The penetration depth increases to several hundred Angstroms as a approaches ac. Above acthere is a rapid increase in penetration depth to a thousand Angstroms or more and the profiling cannot be sensitively controlled. At grazing incidence the peaks are shifted several tenths of a degree by the x-ray refraction and an experimental procedure for calculating the shifts is described. The method is illustrated with an analysis of iron oxide films. © 1987, Materials Research Society. All rights reserved.