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:
Sep. 06, 1994
Filed:
Aug. 14, 1992
Kuo-Hsin Huang, Sunnyvale, CA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A light emitting diode is epitaxially grown on a semiconductor substrate. A lower cladding layer is grown on the substrate and doped to have n-type conductivity. An active layer is deposited on the lower cladding layer, and a p-type upper cladding layer is deposited on the active layer. A relatively thin lower window layer is then deposited on the upper cladding layer, and doped with a first p-type dopant material. A relatively thick upper window layer is then deposited on the lower window layer, and doped with a different p-type dopant material. The layer with a dopant different from the principal portion of the window serves to limit diffusion of dopant through the active layer. The dopant in the diffusion limiting layer can diffuse in both directions, thereby reducing the driving force of diffusion. As a result, the p-type dopant intersects a steep portion of the concentration gradient of n-type dopant quite near the interface between the lower cladding layer and active layer, resulting in high light output power. A diffusion limiting layer having a different dopant than a substrate may be used for forming a LED with a p-type substrate and an n-type layer near the upper face.