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:
Oct. 04, 1988
Filed:
Sep. 04, 1986
Edgar Borchert, Warstein, DE;
Holger Schoof, Ruthen, DE;
Karl H Sommer, Warstein, DE;
Alois Sonntag, Warstein, DE;
Licentia Patent-Verwaltungs- GmbH, Frankfurt, DE;
Abstract
An asymmetrical thyristor having an n.sup.+ pn.sup.- np.sup.- zone sequence whose functionability is not impaired and, in particular, whose reverse blocking characteristic is not degraded, if it fires after a forward current load and subsequent commutation before its turn-off time has expired due to the positive voltage increasing again. This insensitivity to refiring after commutation when falling below the turn-off time is realized by a flat rise of the doping concentration from the n.sup.- -type zone to the n-type zone, with the doping concentration in the n-type layer increasing approximately exponentially over a path of at least 50.mu.. In order to keep the forward off-state current low with a flat nn.sup.- junction, the thickness and doping of the n.sup.- -type layer are dimensioned such that at the highest intended forward off-state voltage the electric field intensity at the pn.sup.- junction is about 1.5.multidot.10.sup.5 V/cm, drops approximately linearly in the n.sup.- -type layer and, at the nn.sup.- junction, has approximately 1/4 of the value it has at the pn.sup.- junction. Methods for producing such a thyristor are also disclosed.