Semiconductor optical waveguide

• US 5,682,455 A
• Filed: 02/29/1996
• Issued: 10/28/1997
• Est. Priority Date: 02/29/1996
• Status: Expired due to Fees

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Kovacic, Stephen J., Ojha, Jugnu J.
• Primary Examiner(s): Ullah, Akm E.
• Application Number:
  US08/609,930
• Time in Patent Office: 607 Days
• Field of Search: 257/17, 257/18, 257/19, 257/22, 257/14, 385/130, 385/131, 385/132, 385/141, 385/2, 385/14, 372/45, 372/46, 372/96, 372/50, 437/19, 437/22, 437/110, 437/133, 437/147, 437/167, 437/936, 437/24, 437/129
• US Class Current: 385/131
• CPC Class Codes: G02B 2006/12061 Silicon
• CPC Class Codes: G02B 6/10 of the optical waveguide type G02B6/02, G02B6/24 take precedence; devices or arrangements for the control of light by electric, magnetic, electro-magnetic or acoustic means G02F1/00; transferring the modulation of modulated light G02F2/00; optical logic elements G02F3/00; optical analogue/digital converters G02F7/00
• CPC Class Codes: G02B 6/12004 Combinations of two or more optical elements
• CPC Class Codes: G02B 6/122 Basic optical elements, e.g. light-guiding paths
• CPC Class Codes: H01L 31/02327 the optical elements being integrated or being directly associated to the device, e.g. back reflectors optical coatings H01L31/0216
• CPC Class Codes: H01L 31/105 the potential barrier being of the PIN type
• CPC Class Codes: H01L 31/1812 including only AIVBIV alloys, e.g. SiGe
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

A channel waveguide structure which can be incorporated into VLSI (very large scale integration) integrated circuits uses a SiGe (silicon germanium) alloy core and Si (silicon) top and bottom cladding layers. The core may consist of only a SiGe alloy layer or it may be formed as a superlattice containing Si layers alternating with SiGe alloy layers. LOCOS (locally oxidized silicon) regions are formed on the top cladding layer at spaced locations thereby defining lateral boundaries of channels in the core.

Claims

1. A semiconductor optical channel waveguide comprising:

a silicon substrate;

a bottom cladding layer made of silicon formed on the silicon substrate;

a top cladding layer made of silicon;

a core formed between the bottom cladding layer and the top cladding layer and comprising at least one layer of a silicon semiconductor alloy, the core having a predetermined increase in the index of refraction relative to the top and bottom cladding layers; and

first and second spaced LOCOS (locally oxidized silicon) regions formed in the top cladding layer thereby defining lateral boundaries of a channel in the core.

2. A structure according to claim 1 wherein the layers within the core comprise a crystal which is substantially free of dislocations.

3. A structure according to claim 2 wherein the core is formed of a single layer of a silicon semiconductor alloy.

4. A structure according to claim 2 wherein the core comprises a series of layers each of which is silicon or a silicon alloy.

5. A structure according to claim 4 wherein the series of layers comprise layers of silicon alternating with layers of silicon alloy.

6. A structure according to claim 4 wherein the series of layers comprise a superlattice.

7. A structure according to claim 4 wherein the series of layers comprise a multiple quantum well.

8. A structure according to claim 2 wherein the silicon alloy in the core is Si_1-x Ge_x where x is in the range 1>

x>

0, and where x is selected to provide said predetermined increase in the index of refraction in the core.

9. A structure according to claim 3 wherein the silicon alloy in the core is Si_1-x Ge_x where x is in the range 1>

x>

0, and where x is selected to provide said predetermined increase in the index of refraction in the core.

10. A structure according to claim 4 wherein the silicon alloy in the core is Si_1-x Ge_x where x is in the range 1>

x>

0, and where x is selected to provide said predetermined increase in the index of refraction in the core.

11. A structure according to claim 5 wherein the silicon alloy in the core is Si_1-x Ge_x where x is in the range 1>

x>

0, and where x is selected to provide said predetermined increase in the index of refraction in the core.

12. A structure according to claim 2 wherein the silicon alloy is Si_1-x Ge_x where x is in the range 0.01-0.1, and where x is selected to provide said predetermined increase in the index of refraction in the core.

13. A structure according to claim 3 wherein the silicon alloy is Si_1-x Ge_x where x is in the range 0.01-0.1, and where x is selected to provide said predetermined increase in the index of refraction in the core.

14. A structure according to claim 4 wherein the silicon alloy is Si_1-x Ge_x where x is in the range 0.01-0.1, and where x is selected to provide said predetermined increase in the index of refraction in the core.

15. A structure according to claim 5 wherein the silicon alloy is Si_1-x Ge_x where x is in the range 0.01-0.1, and where x is selected to provide said predetermined increase in the index of refraction in the core.

16. A structure according to claim 2 wherein the core and cladding layers comprise a crystal which is substantially free of dislocations.

17. A structure according to claim 16 wherein regions of n+doping or regions of p+doping are buried in the bottom cladding layer or in the substrate.

18. A structure according to claim 16 wherein a layer of n+doping or p+doping is buried in the bottom cladding layer or in the substrate.

19. A structure according to claim 16 wherein

a region of n+doping is buried in the bottom cladding layer or in the substrate;

the bottom cladding layer, core layer and top cladding layer are n-doped;

further comprising a p+doped layer of silicon overlying said top cladding layer above said buried n+doped region;

thereby forming a P-i-N photodetector diode.

20. A structure according to claim 16 wherein

a region of p+doping is buried in the bottom cladding layer or in the substrate;

the bottom cladding layer, core layer and top cladding layer are n-doped;

further comprising a n+doped layer of silicon overlying said top cladding layer above said buried n+doped region;

thereby forming an N-i-P photodetector diode.

21. A structure according to claim 16 wherein the bottom cladding layer, core layer and top cladding layer are n-doped.

22. A semiconductor optical channel waveguide comprising:

a substrate;

a bottom cladding layer made of silicon or a silicon alloy formed on the substrate;

a top cladding layer made of silicon or a silicon alloy enabling the formation of a silicon oxide;

a core formed between the bottom cladding layer and the top cladding layer and comprising at least one layer of a silicon semiconductor alloy, the core having a predetermined increase in the index of refraction relative to the top and bottom cladding layers; and

first and second spaced LOCOS regions formed in the top cladding layer thereby defining lateral boundaries of a channel in the core.

23. A VLSI integrated circuit comprising:

a silicon substrate;

a bottom cladding layer made of silicon and formed on the silicon substrate;

a top cladding layer made of silicon;

a core formed between the bottom cladding layer and the top cladding layer and comprising at least one layer of a silicon semiconductor alloy, the core and cladding layers forming a crystal which is substantially dislocation free, the core having a predetermined increase in the index of refraction relative to the top and bottom cladding layers; and

a plurality of spaced LOCOS regions formed in the top cladding layer thereby defining lateral boundaries of respective channels in the core, at least one of the channels serving as a waveguide.