Semiconductor layer structure with superlattice

• US 7,893,424 B2
• Filed: 07/20/2007
• Issued: 02/22/2011
• 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: Miler, Andreas, Lell, Alfred, Schillgalies, Marc, Eichler, Christoph
• Primary Examiner(s): MENZ, LAURA MARY
• Application Number:
  US11/780,514
• Publication Number:
  US 20080054247A1
• Time in Patent Office: 1,313 Days
• Field of Search: 257/13, 257/22, 372/45.012
• US Class Current: 257/13
• 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 33/04 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 5/0422 with n- and p-contacts on the same side of the active layer
• CPC Class Codes: H01S 5/2009 by using electron barrier layers
• CPC Class Codes: H01S 5/3063 using Mg
• CPC Class Codes: H01S 5/3213 asymmetric clading layers
• CPC Class Codes: H01S 5/3215 graded composition cladding layers
• CPC Class Codes: H01S 5/3216 quantum well or superlattice cladding layers
• CPC Class Codes: H01S 5/3218 specially strained cladding layers, other than for strain compensation
• 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 includes a superlattice composed of stacked layers of III-V compound semiconductors of a first and at least one second type. Adjacent layers of different types in the superlattice differ in composition with respect to at least one element, at least two layers of the same type have a different content of the at least one element, the content of the at least one element is graded within a layer of the superlattice, and the layers of the superlattice contain dopants in predefined concentrations, with the superlattice comprising layers that are doped with different dopants. In this way, the electrical, optical and epitaxial properties of the superlattice can be adapted in the best possible manner to given requirements, particularly epitaxial constraints.

Claims

1. A semiconductor layer structure, comprising a superlattice composed of stacked layers of a first and at least one second type, wherein

said layers of said first type and of said at least one second type are III-V compound semiconductors,

adjacent layers of different types in said superlattice differ in composition with respect to at least one element,

at least two layers of the same type in said superlattice have a different content of at least one element,

the content of at least one element is graded within a said layer of said superlattice, and

said layers of said superlattice contain dopants in predefined concentrations, with said superlattice comprising layers that are doped with different dopants.

2. 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.

3. 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.

4. The semiconductor layer structure as in claim 1, wherein the individual said layers of said superlattice are each assigned a vertical position within said semiconductor layer structure, and the content of at least one element in a layer is dependent in a predetermined manner on the vertical position of that layer within said semiconductor layer structure.

5. The semiconductor layer structure as in claim 4, wherein said dependence of the content of at least one element on said vertical position is defined by a common function for all said layers of said superlattice.

6. The semiconductor layer structure as in claim 4, wherein said dependence of the content of at least one element on said vertical position is defined by a first function for layers of said first type and by at least one second function for layers of said at least one second type.

7. The semiconductor layer structure as in claim 5, wherein said first and/or said at least one second and/or said common function is a step function or a monotonously rising/falling function or a linear function or a polynomial function or an exponential function or a logarithmic function or a periodic function or a superposition of the aforesaid functions or contains fractions of one of said functions.

8. The semiconductor layer structure as in claim 1, wherein the content of at least one element is constant within a said layer of said superlattice.

9. The semiconductor layer structure as in claim 1, wherein all said layers have the same thickness.

10. The semiconductor layer structure as in claim 1, wherein said layers of different types have different thicknesses.