Semiconductor layer structure with superlattice

• US 7,822,089 B2
• Filed: 07/20/2007
• Issued: 10/26/2010
• Est. Priority Date: 07/27/2006
• Status: Active Grant

• Current Assignee: OSRAM OLED GMBH (Ams-Osram AG)
• Original Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Inventors: Eichler, Christoph, Lell, Alfred
• Primary Examiner(s): Harvey; Minsun
• Assistant Examiner(s): Nguyen; Phillip
• Application Number:
  US11/780,512
• Publication Number:
  US 20080025360A1
• Time in Patent Office: 1,194 Days
• Field of Search: 372/43.01, 372/45.012
• US Class Current: 372/45.012
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/025 Physical imperfections, e.g. particular concentration or distribution of impurities
• 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 33/32 containing nitrogen
• CPC Class Codes: H01S 5/0213 Sapphire, quartz or diamond based substrates
• CPC Class Codes: H01S 5/0422 with n- and p-contacts on the same side of the active layer
• CPC Class Codes: H01S 5/3063 using Mg
• CPC Class Codes: H01S 5/3077 plane dependent doping
• CPC Class Codes: H01S 5/3213 asymmetric clading layers
• CPC Class Codes: H01S 5/3216 quantum well or superlattice cladding 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

The semiconductor layer structure comprises a superlattice (9) composed of alternately stacked layers (9a, 9b) of III-V semiconductor compounds of a first composition (a) and at least one second composition (b). The layers (9a, 9b) of the superlattice (9) contain dopants in predetermined concentrations, with regard to which the concentrations of the dopants are different at least two layers of a same composition in the superlattice (9), the concentration of the dopants is graded within at least one layer (9a, 9b) of the superlattice (9), and the superlattice (9) comprises layers that are doped with different dopants or comprise at least one layer (9a, 9b) that is undoped. The electrical and optical properties of the superlattice (9) can be adapted to given requirements in the best possible manner in this way.

Claims

1. A semiconductor layer structure, comprising a superlattice composed of alternately stacked layers of III-V compound semiconductors of a first composition and at least one second composition, wherein said layers contain dopants in predetermined concentrations, said concentrations of said dopants are different in at least two layers of a same composition in said superlattice, said concentration of said dopants is graded within at least one said layer of said superlattice, said superlattice comprises layers that are doped with different dopants and said superlattice comprises at least one layer that is undoped.

3. The semiconductor layer structure as in claim 1, wherein said superlattice comprises alternately stacked In_xAl_yGa_1-x-yN and In_wAl_zGa_1-w-zN layers, where 0≦

x,y,w,z≦

1 and x+y≦

1 and w+z≦

1.

4. The semiconductor layer structure as in claim 1, wherein said superlattice comprises alternately stacked In_xAl_yGa_1-x-yP and In_wAl_zGa_1-w-zP layers, where 0≦

x,y,w,z≦

1 or alternately stacked In_xAl_yGa_1-x-yAs and In_wAl_zGa_1-w-zAs layers, where 0≦

x,y,w,z≦

1 and x+y≦

1 and w+z≦

1.

5. The semiconductor layer structure as in claim 1, wherein individual layers of said superlattice are assigned a vertical position z within said semiconductor layer structure and the concentration of dopants in a said layer changes at least in part in a predetermined manner depending on the vertical position z of that layer within said semiconductor layer structure.

6. The semiconductor layer structure as in claim 5, wherein the dependence of said concentration of said dopants on said vertical position z is defined by a common function for all said layers of said superlattice.

7. The semiconductor layer structure as in claim 5, wherein the dependence of said concentration of said dopants on said vertical position z is defined by a first function for said layers of said first composition and by at least one second function for said layers of said at least one second composition.

8. The semiconductor layer structure as in claim 6, wherein said common function is a step function or a monotonously rising/falling function or a linear function or a polynomial function or a root function or an exponential function or a logarithmic function or a periodic function or a superposition of said functions or contains fractions of one of said functions.

9. The semiconductor layer structure as in claim 1, wherein said concentration of said dopants is constant within at least one said layer of said superlattice.

10. The semiconductor layer structure as in claim 1, wherein said dopants are Mg and/or Si.

11. An optoelectronic component comprising a semiconductor layer structure as in claim 1.

12. The optoelectronic component as in claim 11, which comprises an optically active layer and wherein said concentration of said dopants in layers of at least one of said compositions increases within said superlattice of said semiconductor layer structure with increasing distance from said optically active layer.

13. The optoelectronic component as in claim 12, which is a light-emitting diode.

14. The optoelectronic component as in claim 12, which is a laser diode.

15. The semiconductor layer structure as in claim 7, wherein said first and/or said at least one second function is a step function or a monotonously rising/falling function or a linear function or a polynomial function or a root function or an exponential function or a logarithmic function or a periodic function or a superposition of said functions or contains fractions of one of said functions.

2. A semiconductor layer structure, comprising a superlattice composed of alternately stacked layers of III-V compound semiconductors of a first composition and at least one second composition, wherein said layers contain dopants in predetermined concentrations, said concentrations of said dopants are different in at least two layers of a same composition in said superlattice, and said concentration of said dopants is graded within at least one said layer of said superlattice, and wherein said superlattice comprises at least one layer that is undoped.

16. The semiconductor layer structure as in claim 2, wherein individual layers of said superlattice are assigned a vertical position z within said semiconductor layer structure and the concentration of dopants in a said layer depends in a predetermined manner on the vertical position z of that layer within said semiconductor layer structure.

17. An optoelectronic component comprising a semiconductor layer structure as in claim 2.

18. The optoelectronic component as in claim 17, which comprises an optically active layer and wherein said concentration of said dopants in layers of at least one of said compositions increases within said superlattice of said semiconductor layer structure with increasing distance from said optically active layer.

19. The optoelectronic component as in claim 18, wherein the optoelectronic component is a light-emitting diode or a laser diode.