DETERMINATION OF MISCUT ANGLES FOR CRYSTALLINE SUBSTRATES

Sybolt Harkema

Low Temperature Division, Dept. of Applied Physics, University of Twente, POB 217, 7500AE Enschede, the Netherlands. (e-mail: s.harkema@tn.utwente.nl)

Keywords: miscut angle, crystalline substrates

The properties of epitaxial layers are influenced by the miscut angle: the angle between the surface and the crystallographic axis perpendicular to which the crystal is supposed to have been cut. For the selection of well cut substrate specimens a fast procedure for the miscut angles is highly desirable. The procedure used in our laboratory uses a single crystal diffractometer, equipped with a small laser.

In the first step the orientation matrix of the crystal has to be determined. For normal substrates like STO or MgO this can be done from a single phi scan (e.g. reflections from four {101} planes can be found from one rotation around [001]).

In the next step a (psi)rotation around the scattering vector is made. During this rotation a trace is made of the reflection of a laser spot from the surface of the substrate. From the elliptical shape of this spot it is possible to determine size and orientation of the miscut angle. The accuracy of the method is better than 0.05 degree. The time for one measurement is in the order of 20 minutes.