The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 23, 1991
Filed:
May. 11, 1990
Helmut Foell, Munich, DE;
Volker Lehmann, Munich, DE;
Siemens Aktiengesellschaft, Munich, DE;
Abstract
The measurement of the diffusion length of minority charge carriers in a semiconductor crystal body is enabled in that the front side and the rear side of the crystal wafer are each respectively brought into contact with an electrolyte in a respective measuring cell and an inhibiting space charge zone is generated at the front side of the wafer. The front side is irradiated with light having a wave length of .lambda.>800 nm and the front side photocurrent I.sub.1 of the minority charge carriers thereby generated is measured. The diffusion length L can be calculated from the photocurrent I.sub.1 with the assistance of a mathematical equation. The topical distribution of the diffusion length L is obtained given point-by-point irradiation and scanning over the crystal wafer. Diffusion lengths of L<150 .mu.m can be measured by selecting a light source having a wave length of .lambda.>800 nm.