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. 17, 2009
Filed:
May. 31, 2006
Akihiro Hasegawa, Hashima, JP;
Akihiro Hasegawa, Hashima, JP;
Sanyo Electric Co., Ltd., Moriguchi, JP;
Abstract
In a laser pickup photodetector of an optical disk playback device, the sensitivity to blue light is improved. On a main surface of a semiconductor substrate, a high resistivity epitaxial layer that becomes an i layer of a PIN photodiode (PIN-PD) is formed. On a surface of the epitaxial layer, two trenches are formed, on a surface of one trench an Nregion that becomes a cathode region of the PIN-PD is formed, and on a surface of the other trench a Pregion that becomes an anode region is formed. When the cathode region and the anode region are set in a reverse bias state, a light receiving semiconductor region that is an i layer between the cathode region and anode region is depleted. The depleted layer expands to a surface of the semiconductor substrate. Accordingly, for blue light having a short wavelength, signal charges can be generated on a surface of the semiconductor substrate and the cathode region can collect the signal charges and extract the charges as a light receiving signal.