Multicomponent barrier layers in quantum well active regions to enhance confinement and speed

• US 20050129078A1
• Filed: 10/01/2004
• Published: 06/16/2005
• Est. Priority Date: 12/21/1998
• Status: Active Grant

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Finisar Corporation (II-VI Incorporated)
• Inventors: Johnson, Ralph H.
• Granted Patent: US 7,257,143 B2
• Time in Patent Office: Days
• US Class Current: 372/50.100
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01S 2302/00 Amplification / lasing wavelength
• CPC Class Codes: H01S 5/18308 having a special structure for lateral current or light confinement
• CPC Class Codes: H01S 5/3201 incorporating bulkstrain effects, e.g. strain compensation, strain related to polarisation
• CPC Class Codes: H01S 5/32358 containing very small amounts, usually less than 1%, of an additional III or V compound to decrease the bandgap strongly in a non-linear way by the bowing effect
• CPC Class Codes: H01S 5/32366 (In)GaAs with small amount of N
• CPC Class Codes: H01S 5/34 comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers H01S5/36 takes precedence
• CPC Class Codes: H01S 5/3403 having a strained layer structure in which the strain performs a special function, e.g. general strain effects, strain versus polarisation
• CPC Class Codes: H01S 5/3406 including strain compensation
• CPC Class Codes: H01S 5/34306 emitting light at a wavelength longer than 1000nm, e.g. InP based 1300 and 1500nm lasers
• CPC Class Codes: H01S 5/34313 with a well layer having only As as V-compound, e.g. AlGaAs, InGaAs
• CPC Class Codes: H01S 5/34346 characterised by the materials of the barrier layers
• CPC Class Codes: H01S 5/34353 based on (AI)GaAs

Abstract

Multi-component barrier layers include formation of a GaAs layer and at least one adjacent GaAsN layer. The resulting multi-component barrier layer shape can provide enhanced (extended) offset for capture of holes and enhanced electrons. Other benefits include: a small amount of strain compensation; poorer spatial overlap of higher confined states reducing parasitics at high bias, with some small effect on the lowest confined states. Quantum wells and associated barriers layers can be grown with combinations of gallium, (Ga), arsenic, (As), nitrogen (N), aluminum (Al), antimony (Sb), phosphorous (P) and/or indium (In) placed within or about a typical GaAs substrate to achieve long wavelength VCSEL performance, e.g., with wavelengths over 1200 nm. Layers of strained quantum well material can also be supported by mechanical stabilizers.

Claims

1. A vertical cavity surface emitting laser (VCSEL) comprising:

an active region having a first edge and a second edge, said active region further comprising at least one quantum well and at least one multi-component barrier, said at least one multi-component barrier layer disposed next to said at least one quantum well, wherein a portion of said at least one multi-component barrier layer comprises a reduced barrier energy to carrier flow near said at least one quantum well, thereby enhancing the speed and efficiency of the device; and

first and second confinement regions each comprising at least one confinement layer, wherein said first confinement region is disposed next to and outside of said first edge of said active region and said second confinement region is disposed next to and outside of said second edge of said active region.

2. A VCSEL as defined in claim 1, wherein barrier energy to carrier flow is reduced immediately adjacent to said at least one quantum well on at least one of the input side or the output side of said at least one quantum well where said reduced barrier is located.

3. A VCSEL as defined in claim 2, wherein the quantum well portion of the active region comprises at least In, Ga, As, and N, and the barrier layer components comprise Ga, As, and N.

4. A VCSEL as defined in claim 2, wherein said at least one quantum well of said active region includes a reduced barrier layer only deployed on the carrier input side of said quantum well.

5. A VCSEL as defined in claim 2, wherein said at least one quantum well of said active region includes a reduced barrier layer only deployed on the carrier output side of said quantum well.

6. A VCSEL as defined in claim 1, wherein the active region includes layers formed using GaAs and at least one of In, N, P, or Sb.

7. A VCSEL as defined in claim 6, wherein the quantum well portion of the active region comprises at least In, Ga, As, and N, and the barrier layer components comprise Ga, As, and nitrogen.

8. A VCSEL as defined in claim 1, wherein the confining regions include layers formed using GaAs and Al.

9. A VCSEL as defined in claim 8, further comprising extended barrier layers disposed between said active region and said confining regions where nitrogen is used in the active region.

10. A VCSEL as defined in claim 1, further comprising at least one extended barrier layer disposed between said confinement regions and any barrier layers or quantum wells containing nitrogen and associated with said active region when said at least one confinement layers include Al.

11. A VCSEL as defined in claim 10, wherein said barrier layers include nitrogen.

12. A VCSEL as defined in claim 10, wherein said quantum wells include nitrogen.

13. A VCSEL as defined in claim 1, wherein said at least one quantum well further comprises layers of a semiconductor alloy under mechanical stress interspersed with thin layers of a substrate type material used in the device and said substrate type material layers serving as mechanical stabilizers for the semiconductor alloy layers to prevent the semiconductor alloy layers from relaxing.

14. A vertical cavity surface emitting laser (VCSEL), comprising:

an active region having a first edge and a second edge, said active region further comprising at least one quantum well containing nitrogen and at least one multi-component barrier, said at least one multi-component barrier layer disposed next to said at least one quantum well, said multi-component barrier layer further comprising a layer of GaAs disposed next to a layer of GaAsN, wherein a portion of said at least one multi-component barrier layer comprises a reduced barrier energy to carrier flow near said at least one quantum well, thereby enhancing the speed and efficiency of the device; and

first and second confinement regions further comprising at least one confinement layer, wherein said first confinement region is disposed next to and outside of said first edge of said active region and said second confinement region is disposed next to and outside of said second edge of said active region.

15. A VCSEL as defined in claim 14, wherein barrier energy to carrier flow is reduced immediately adjacent to said at least one quantum well on at least one of the input side and the output side of said at least one quantum well where said reduced barrier is located.

16. A VCSEL as defined in claim 15, wherein the quantum well portion of the active region comprises at least In, Ga, As, and N, and the GaAsN layer of said multi-component barrier layer includes at least one of In and Sb.

17. A VCSEL as defined in claim 15, wherein said at least one quantum well of said active region includes a reduced barrier layer only deployed on the carrier input side of said quantum well.

18. A VCSEL as defined in claim 16 wherein the quantum well portion of the active region comprises at least In, Ga, As, and N, and the barrier layer components comprise Ga, As, and nitrogen.

19. A VCSEL as defined in claim 14, wherein the confining regions includes layers formed using GaAs and Al.

20. A VCSEL as defined in claim 19, further comprising extended barrier layers disposed between said active region and said confining regions where nitrogen is used in the active region.

21. A VCSEL as defined in claim 14, further comprising at least one extended barrier layer disposed between said confinement regions and any barrier layers or quantum wells containing nitrogen and associated with said active region when said at least one confinement layers include Al.

22. A vertical cavity surface emitting laser (VCSEL) comprising:

an active region having a first edge and a second edge, said active region further comprising at least one quantum well containing nitrogen and at least one multi-component barrier, said at least one multi-component barrier layer disposed next to said at least one quantum well, said multi-component barrier layer further comprising a layer of GaAs disposed next to a layer of GaAsN, wherein a portion of said at least one multi-component barrier layer comprises a reduced barrier energy to carrier flow near said at least one quantum well, thereby enhancing the speed and efficiency of the device; and

first and second confinement regions further comprising at least one confinement layer including Al; and

an extended barrier layer disposed between said first confinement regions and said active region.

23. A VCSEL as defined in claim 22, wherein the quantum well portion of the active region comprises at least In, Ga, As, and N, and the GaAsN layer of said multi-component barrier layer includes at least one of In and Sb.