Method of manufacturing semiconductor light emitting device

• US 5,792,698 A
• Filed: 08/22/1996
• Issued: 08/11/1998
• Est. Priority Date: 12/09/1993
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nishitani, Katsuhiko
• Primary Examiner(s): KUNEMUND, ROBERT M
• Application Number:
  US08/701,404
• Time in Patent Office: 719 Days
• Field of Search: 117/89, 117/93, 117/102, 438/287, 438/289
• US Class Current: 438/287
• CPC Class Codes: H01L 33/0062 for devices with an active region comprising only III-V compounds
• CPC Class Codes: H01L 33/025 Physical imperfections, e.g. particular concentration or distribution of impurities
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table

Abstract

A method of manufacturing a semiconductor light emitting device employs an MOCVD process. The method sequentially forms, on a GaAs substrate, at least an InGaAlP clad layer, an active layer, an InGaAlP clad layer, a GaAlAs or InGaAlP current diffusion layer, and a GaAlAs or InGaAlP light scattering layer. The flow-rate ratio (V/III ratio) of a V-group source gas to a III-group source gas for forming the light scattering layer is smaller than that for forming the current diffusion layer. As a result, the surface of the light scattering layer is roughened to improve light emission efficiency.

Claims

1. A method of manufacturing a semiconductor light emitting diode for emitting light from a top surface of epitaxially grown stacked layers, the method comprising the steps of metal-organic chemical vapor deposition (MOCVD) of:

(1) sequentially forming a light reflection layer on a GaAs substrate, an InGaAlP bottom clad layer on the light reflection layer, an active layer on the bottom clad layer, and an InGaAlP top clad layer on the active layer, the surface of each layer being essentially parallel with a top surface of the GaAs substrate respectively;

(2) forming a current diffusion layer from GaAlAs or InGaAlP on the top clad layer with a first V/Ill ratio; and

(3) forming a light scattering layer having surface irregularities from GaAlAs or InGaAlP on the current diffusion layer with a second V/III ratio, the surface irregularities having an optical roughness sufficient to scatter the light, wherein the second V/III ratio is smaller than the first V/III ratio, and the value of second V/IlI ratio is small enough to generate the surface irregularities, and said steps (1), (2), and (3) are processed continuously without exposing the epitaxially grown stacked layer to the atmosphere during the continuous process.

2. A method of claim 1, wherein the light scattering layer is made from GaAlAs with the second V/III ratio being 20 or below.

3. A method of claim 2, wherein said second V/III ratio is 10 to 20.

4. A method of claim 3, wherein said second V/III ratio changes in the range between 10 to 20 during the formation of the light scattering layer.

5. A method of claim 1, wherein the light scattering layer is made from InGaAlP with the second V/III ratio being 150 or below.

6. A method of claim 5, wherein said second V/III ratio is 100 to 150.

7. A method of claim 6, wherein said second V/III ratio changes in the range between 100 to 150 during the formation of the light scattering layer.

8. A method of claim 1, wherein a GaAs buffer layer is formed on the GaAs substrate, and the light reflection layer is formed on the GaAs buffer layer.

9. A method of claim 1, further comprising a step of forming a metal electrode on a part of said light scattering layer.

10. A method of claim 1, wherein said light reflection layer is a quarter-wave stack mirror consisting of plural paired layers of InAlP and GaAs.