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:
Nov. 16, 2004
Filed:
Jan. 21, 2003
Applicant:
Inventors:
Assignee:
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G01R 2/728 ; H01L 2/100 ;
U.S. Cl.
CPC ...
G01R 2/728 ; H01L 2/100 ;
Abstract
In a method for evaluating a crystalline semiconductor substrate which includes a collector layer, a base layer, and an emitter layer and is used for a heterojunction bipolar transistor, a layer is provided having the same composition as the base layer. The semiconductor substrate is irradiated with excitation light and change with time in intensity of photoluminescence from the layer is measured before the intensity becomes saturated. The change with time in current gain of the heterojunction bipolar transistor produced using the semiconductor substrate is determined from the change with time in the intensity.