Light emitting device having a plurality of light emitting cells and method of fabricating the same

• US 7,772,601 B2
• Filed: 07/05/2005
• Issued: 08/10/2010
• Est. Priority Date: 02/04/2005
• Status: Active Grant

• Current Assignee: Seoul Viosys Co., Ltd. (Seoul Semiconductor Co., Ltd.)
• Original Assignee: Seoul Optodevice Company Limited (Seoul Semiconductor Co., Ltd.)
• Inventors: Speck, James S., Kim, Hong San, Lee, Chung Hoon
• Primary Examiner(s): HO, TU TU V
• Application Number:
  US11/815,255
• Publication Number:
  US 20080197363A1
• Time in Patent Office: 1,862 Days
• Field of Search: 257/88, 257/99, 257/503, 257/705, 257/713, 257/E33.075, 438/34, 438/45, 438/46
• US Class Current: 257/88
• CPC Class Codes: H01L 2224/48095 Kinked
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 27/153 in a repetitive configuration, e.g. LED bars
• CPC Class Codes: H01L 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H01L 33/64 Heat extraction or cooling elements

Abstract

Disclosed is a light emitting device having a plurality of light emitting cells. The light emitting device comprises a thermally conductive substrate, such as a SiC substrate, having a thermal conductivity higher than that of a sapphire substrate. The plurality of light emitting cells are connected in series on the thermally conductive substrate. Meanwhile, a semi-insulating buffer layer is interposed between the thermally conductive substrate and the light emitting cells. For example, the semi-insulating buffer layer may be formed of AlN or semi-insulating GaN. Since the thermally conductive substrate having a thermal conductivity higher than that of a sapphire substrate is employed, heat-dissipating performance can be enhanced as compared with a conventional sapphire substrate, thereby increasing the maximum light output of a light emitting device that is driven under a high voltage AC power source. In addition, since the semi-insulating buffer layer is employed, it is possible to prevent an increase in a leakage current through the thermally conductive substrate and between the light emitting cells.

Claims

1. A light emitting device having a plurality of light emitting cells, comprising:

a thermally conductive substrate having a thermal conductivity higher than that of a sapphire substrate;

a plurality of light emitting cells serially connected to one another on the thermally conductive substrate; and

a semi-insulating buffer layer interposed between the thermally conductive substrate and the light emitting cells,

wherein the thermally conductive substrate comprises AlN or SiC,

wherein the semi-insulating buffer layer is formed of semi-insulating GaN doped with an acceptor,

wherein the acceptor is iron (Fe).

2. The device as claimed in claim 1, wherein each of the light emitting cells comprises an N-type semiconductor layer, an active layer, and a P-type semi-conductor layer, and the N-type semiconductor layer and the P-type semi-conductor layer of adjacent light emitting cells are electrically connected in series by means of metallic wiring.