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:
May. 18, 2004
Filed:
Sep. 11, 2000
Takeshi Takagi, Kyoto, JP;
Kenji Harafuji, Osaka, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
There is provided a MQB layer as a multi-quantum barrier portion composed of well layers and barrier layers that are formed of extremely thin films having different compositions and alternately stacked. This enhances an effective barrier height by using the phenomenon that holes likely to flow from a SiGe base layer to a Si emitter layer are reflected by the MQB layer and thereby suppresses the reverse injection of the holes from the SiGe base layer into the Si emitter layer. As a result, the reverse injection of carriers is suppressed by the MQB layer even when the base doping concentration is increased, which provides a satisfactory current amplification factor and increases a maximum oscillation frequency. What results is a bipolar transistor having excellent RF characteristics such as current amplification factor, current gain cutoff frequency, and maximum oscillation frequency in a microwave band or the like.