Semiconductor Material Doping

• US 20160260867A1
• Filed: 03/14/2016
• Published: 09/08/2016
• Est. Priority Date: 12/04/2009
• Status: Active Grant

• Current Assignee: Sensor Electronic Technology Incorporated (Seoul Semiconductor Co., Ltd.)
• Original Assignee: Sensor Electronic Technology Incorporated (Seoul Semiconductor Co., Ltd.)
• Inventors: Shatalov, Maxim S., Gaska, Remigijus, Yang, Jinwei, Shur, Michael, Dobrinsky, Alexander
• Granted Patent: US 9,634,183 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 29/15 Structures with periodic or quasi periodic potential variation, e.g. multiple quantum wells, superlattices such structures applied for the control of light G02F1/017, applied in semiconductor lasers H01S5/34
• CPC Class Codes: H01L 29/155 Comprising only semiconductor materials H01L29/154 takes precedence
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 29/201 including two or more compounds , e.g. alloys H01L29/2006 takes precedence
• CPC Class Codes: H01L 29/207 further characterised by the doping material H01L29/2006 takes precedence
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/145 with a current-blocking structure
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/325 characterised by the doping materials
• CPC Class Codes: H01S 5/2009 by using electron barrier layers
• CPC Class Codes: H01S 5/3211 characterised by special cladding layers, e.g. details on band-discontinuities
• CPC Class Codes: H01S 5/3216 quantum well or superlattice cladding layers
• CPC Class Codes: H01S 5/3407 characterised by special barrier layers
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

A solution for designing and/or fabricating a structure including a quantum well and an adjacent barrier is provided. A target band discontinuity between the quantum well and the adjacent barrier is selected to coincide with an activation energy of a dopant for the quantum well and/or barrier. For example, a target valence band discontinuity can be selected such that a dopant energy level of a dopant in the adjacent barrier coincides with a valence energy band edge for the quantum well and/or a ground state energy for free carriers in a valence energy band for the quantum well. Additionally, a target doping level for the quantum well and/or adjacent barrier can be selected to facilitate a real space transfer of holes across the barrier. The quantum well and the adjacent barrier can be formed such that the actual band discontinuity and/or actual doping level(s) correspond to the relevant target(s).

Claims

1. A method of fabricating a group III nitride semiconductor structure, the method comprising:

designing a superlattice layer including a quantum well and an immediately adjacent barrier to facilitate a real space transfer of holes across the immediately adjacent barrier, wherein the designing includes;

selecting a target valence band discontinuity between the quantum well and the immediately adjacent barrier such that a dopant energy level of a barrier dopant in the immediately adjacent barrier is at least one of;

within three thermal energies of a valence energy band edge for the quantum well or substantially aligned with a ground state energy for free carriers in a valence energy band for the quantum well; and

selecting a target thickness of each of the quantum well and the adjacent barrier based on a characteristic size of a wave function for the dopant in the immediately adjacent barrier, wherein the target thickness is less than the characteristic size; and

forming the quantum well and the adjacent barrier in the structure using group III nitride materials having an actual valence band discontinuity corresponding to the target valence band discontinuity, and actual thicknesses equal to or less than the target thicknesses.

2. The method of claim 1, the designing further including selecting the group III nitride materials such that the superlattice layer is at least partially transparent to ultraviolet radiation of a target wavelength.

3. The method of claim 1, the designing further comprising selecting a target quantum well doping level for a quantum well dopant in the quantum well and a target barrier doping level for the barrier dopant in the adjacent barrier to facilitate the real space transfer of holes across the barrier.

4. The method of claim 1, wherein the target thickness is in a range between a single monolayer and the Bohr radius constant.

5. The method of claim 4, wherein the dopant is a deep impurity.

6. The method of claim 1, wherein the characteristic size is estimated using the Bohr radius constant.

7. The method of claim 6, wherein the dopant is a shallow impurity.

8. The method of claim 1, wherein the group III nitride material of the barrier varies along lateral dimensions of the barrier such that a lateral cross section of the barrier includes:

a set of transparent regions, each transparent region having a transmission coefficient for the target wavelength greater than or equal to approximately sixty percent, wherein the set of transparent regions are at least ten percent of an area of the lateral cross section of the barrier; and

a set of higher conductive regions occupying a sufficient area of the area of the lateral cross section of the barrier and having an average resistance per unit area to a vertical current flow resulting in a total voltage drop across the semiconductor structure of less than ten percent of a total voltage drop across the structure.

9. A device comprising:

a radiation generating structure; and

a group III nitride superlattice layer located adjacent to the radiation generating structure, wherein the superlattice layer is at least partially transparent to radiation generated by the radiation generating structure, and wherein the superlattice layer comprises;

a plurality of quantum wells; and

a plurality of barriers alternating with the plurality of quantum wells, wherein a quantum well of the plurality of quantum wells and an immediately adjacent barrier of the plurality of barriers are formed of group III nitride materials having a valence band discontinuity such that a dopant energy level of a barrier dopant in the immediately adjacent barrier is at least one of;

within three thermal energies of a valence energy band edge for the quantum well or substantially aligned with a ground state energy for free carriers in a valence energy band for the quantum well and thicknesses equal to or less than a characteristic size of a wave function for the dopant in the immediately adjacent barrier.

10. The device of claim 9, wherein the thicknesses are in a range between a single monolayer and the Bohr radius constant.

11. The device of claim 10, wherein the dopant is a deep impurity.

12. The device of claim 9, further comprising a p-type contact layer, wherein the superlattice layer is located between the radiation generating structure and the p-type contact layer.

13. The device of claim 12, further comprising an electron blocking layer located between the radiation generating structure and the superlattice layer.

14. The device of claim 9, wherein at least one of:

the plurality of quantum wells or the plurality of barriers, have group III nitride compositions that change across the superlattice layer.

15. The device of claim 9, wherein an acceptor energy level in a barrier of the plurality of barriers varies relative to the valence energy band edge for the barrier.

16. The device of claim 15, wherein the acceptor energy level in the barrier matches the hole levels in both immediately adjacent quantum wells.

17. A method of fabricating a deep ultraviolet light emitting device, the method comprising:

forming a deep ultraviolet light generating structure; and

forming a group III nitride superlattice layer located adjacent to the radiation generating structure, wherein the superlattice layer comprises;

a plurality of quantum wells; and

a plurality of barriers alternating with the plurality of quantum wells, wherein a quantum well of the plurality of quantum wells and an immediately adjacent barrier of the plurality of barriers are formed of group III nitride materials having a valence band discontinuity such that a dopant energy level of a barrier dopant in the immediately adjacent barrier is at least one of;

within three thermal energies of a valence energy band edge for the quantum well or substantially aligned with a ground state energy for free carriers in a valence energy band for the quantum well and thicknesses equal to or less than a characteristic size of a wave function for the dopant in the immediately adjacent barrier.

18. The method of claim 17, further comprising designing the superlattice layer, wherein the designing includes selecting the target valence band discontinuity between the quantum well and the immediately adjacent barrier and the thicknesses of each of the quantum well and the adjacent barrier to facilitate a real space transfer of holes across the immediately adjacent barrier.

19. The method of claim 18, wherein the designing further includes selecting the group III nitride materials such that the superlattice layer is at least partially transparent to ultraviolet radiation emitted by the light generating structure.

20. The method of claim 17, wherein the acceptor energy level in a barrier of the plurality of barriers matches the hole levels in both immediately adjacent quantum wells of the plurality of quantum wells.