Semiconductor structure and method of manufacturing a semiconductor structure

• US 8,062,913 B2
• Filed: 07/02/2010
• Issued: 11/22/2011
• Est. Priority Date: 07/01/2005
• Status: Expired due to Fees

• Current Assignee: Optogan Oy
• Original Assignee: Optogan Oy
• Inventors: Bougrov, Vladislav E., Odnoblyudov, Maxim A.
• Primary Examiner(s): Nguyen; Thinh T
• Application Number:
  US12/829,466
• Publication Number:
  US 20100314662A1
• Time in Patent Office: 508 Days
• Field of Search: 438/22, 438/25, 438/26, 438/27, 438/29, 438/477, 438/565, 438/936, 257/14, 257/98, 257/E21.097, 257/E21.09, 257/E29.024
• US Class Current: 438/22
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/24 of the light emitting region, e.g. non-planar junction
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

A semiconductor structure is formed of nitrides of group III metals having wurtzite crystal structure and grown in vapor phase on a (0001) oriented semiconductor substrate. The structure comprises a bottom cladding layer, a top cladding layer, and a diffusion region positioned between the cladding layers for diffusing light propagating within the semiconductor structure. The diffuse region has refractive index different from those of the cladding layers and non-flat surfaces for providing light diffusing interfaces between the diffusion region and the cladding layers. According to the invention, the diffusion region comprises a plurality of diffusion layers, compositions and thicknesses of said diffusion layers having been chosen to avoid formation of strain-induced dislocations in the diffusion region, and adjacent diffusion layers having different refractive indices in order to further enhance the diffusion efficiency.

Claims

1. A method of manufacturing a semiconductor structure (1) formed of nitrides of group III metals having wurtzite crystal structure and grown in vapor phase on a (0001) oriented semiconductor substrate (2,3), the method comprising steps of

growing in vapor phase a bottom cladding layer (4);

growing in vapor phase a diffusion region (6,7) above the bottom cladding layer for diffusing light propagating within the semiconductor structure (1), the diffusion region having a refractive index different from that of the bottom cladding layer and non-flat surfaces; and

growing in vapor phase a top cladding layer (5) above the diffusion region, the top cladding layer having a flat upper surface (9), a refractive index different from that of the diffusion region, and a lattice constant the same as that of the bottom cladding layer,

characterized in that the growing of the diffusion region comprises steps of growing a plurality of diffusion layers (6,7), compositions and thicknesses of the diffusion layers having been chosen to avoid formation of strain-induced dislocations in the layer interfaces, and adjacent diffusion layers (6,7) having different refractive indices in order to further enhance the diffusion efficiency.

2. A method according to claim 1, characterized in that said nitrides are of the form Al_xGa_I-x-yIn_yN, w herein 0≦

x≦

1 and 0≦

y≦

1.

3. A method according to claim 1, characterized in that said bottom and top cladding layers are of the same material.

4. A method according to claim 3, characterized in that diffusion layers (6,7) are grown having lattice constants the same as that of the cladding layers (4,5).

5. A method according to claim 3, characterized in that diffusion layers (6,7) are grown, each of them having a lattice constant different from that of the cladding layers (4,5), a thickness smaller than the Matthews-Blakeslee critical thickness, and one of two adjacent diffusion layers (6,7) having a lattice constant greater and the other a lattice constant smaller than that of the cladding layers (4,5) in order to avoid strain accumulation in the diffusion layers.

6. A method according to claim 1, characterized in that a bottom cladding layer and diffusion layers are grown, each of them having an upper surface with facets having crystallographic indices other than (0001) and those of the type {1 100}.

7. A method according to claim 6, characterized in that the growing of the bottom cladding layer comprises a step of formation of precipitates (14) on a (0001) oriented surface, said precipitates having a height of 0.1-1.5 μ

m and surface density of 10⁷-10⁸ cm<sup>−

2</sup>.

8. A method according to claim 7, characterized in that said precipitates (14) are formed by a process consisting of a sequence of short low-temperature depositions, performed in temperature range of 450-700°

C., followed by high-temperature layer annealing periods, performed in temperature range of 900-1150°

C.