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Rapid Determination of Dislocation Densities in Crystals

IP.com Disclosure Number: IPCOM000074894D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Biedermann, E: AUTHOR [+2]

Abstract

The determination of dislocation densities measured in the form of the total length of dislocations per crystal volume is of increasing importance to material characterization, particularly in the case of semiconductor crystals.

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Rapid Determination of Dislocation Densities in Crystals

The determination of dislocation densities measured in the form of the total length of dislocations per crystal volume is of increasing importance to material characterization, particularly in the case of semiconductor crystals.

The usual method is based on an X-ray topographic mapping of a crystal area. This mapping is enlarged about 50 times, and the total length of all dislocation lines in a given area is determined in a time consuming and intricate manner.

In order to overcome this disadvantage, the proposed method utilizes the unique relationship between the total length of dislocation in a topographic map and the number of cross-points of an arbitrarily traced counting curve intersecting individual lines of dislocation.

This relationship can be expressed by the following equation:

D(D) = n/2/ Over 4 . 1 Over t . D(P). where D(D) is the dislocation density per unit volume, D(p) the crosspoint density per unit length and t the crystal thickness.

This method permits automatic determination of dislocation densities, since there is no need to topograph the entire crystal or to employ any other method to make the dislocations visible. The crystal is adjusted to a suitable Bragg reflection on a narrow beam of monochromatic X-rays. The line-shaped reflection is scanned in its longitudinal direction by means of a counter and an appropriately fine diaphragm.

The number of intensity maxima counted at a given sca...