Semiconductor light emitting device with an active layer made of semiconductor having uniaxial anisotropy

• US 6,072,197 A
• Filed: 02/24/1997
• Issued: 06/06/2000
• Est. Priority Date: 02/23/1996
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Horino, Kazuhiko, Domen, Kay
• Primary Examiner(s): Tran, Minh Loan
• Application Number:
  US08/805,336
• Time in Patent Office: 1,198 Days
• Field of Search: 257/88, 257/94, 257/103, 257/627, 257/628, 257/98, 372/45, 372/46
• US Class Current: 257/103
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/49 of a plurality of wire connectors
• CPC Class Codes: H01L 27/153 in a repetitive configuration, e.g. LED bars
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/12042 LASER
• CPC Class Codes: H01L 2924/12043 Photo diode
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
• CPC Class Codes: H01L 33/24 of the light emitting region, e.g. non-planar junction
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

A semiconductor light emitting device includes a second semiconductor layer, an active layer, a third semiconductor layer and a pair of electrodes. The second semiconductor layer is formed directly on the principal pane of a substrate or via a first semiconductor layer. The active layer is formed on the second semiconductor layer and has an energy band gap which is smaller than the energy band gap of the second semiconductor layer. The active layer is made of a semiconductor having an uniaxial anisotropy. The third semiconductor layer is formed on the active layer and has the energy band gap which is larger than the energy band gap of the active layer. The pair of electrodes supplies current to the second semiconductor layer, the active layer, and the third semiconductor layer in the film thickness direction. The film thickness direction of at least the active layer is different from the axis of the uniaxial anisotropy.

Claims

1. A semiconductor light emitting device comprising:

a second semiconductor layer formed directly on a principal plane of a crystal substrate via a first semiconductor layer;

an active layer formed on said second semiconductor layer and having an energy band gap which is smaller than an energy band gap of said second semiconductor layer, said active layer is made of semiconductor having uniaxial anisotropy;

a third semiconductor layer formed on said active layer and having an energy band gap which is larger than an energy band gap of said active layer; and

,

a pair of electrodes for supplying current to said second semiconductor layer, said active layer, and said third semiconductor layer in a film thickness direction,

wherein said film thickness direction of at least said active layer is different from an axis of said uniaxial anisotropy, said active layer has triaxis anisotropy by applying distortion in a plane which is not perpendicular to a c axis exhibiting anisotropy, and light is emitted vertically relative to said principal plane.

2. A semiconductor light emitting device according to claim 1, wherein said semiconductor of active layer is wurtzite nitride.

3. A semiconductor light emitting device according to claim 1, wherein said substrate is made of GaN, AlN or SiC, and

said principal a plane is {1 100} plane, {1120} plane or a plane of said substrate inclined at -5 to +5 degree with said a {1 100} plane or said {11 20} plane.

4. A semiconductor light emitting device according to claim 1, wherein said crystal substrate is formed of a LiAlO₂ substrate,

said principal plane is either a {100} plane or face inclined at an angle of -5 to +5 degree with said {100} face.

5. A semiconductor light emitting device according to claim 1, wherein said active layer is formed of Al_x Ga_l-x-y In_y N (where 0≦

x≦

1 and 0≦

y≦

1).

6. A semiconductor light emitting device according to claim 1, furthermore comprising

a mirror layer is formed beneath said second semiconductor layer or on said third semiconductor layer, and

a resonator is formed using said mirror layer as one end surface in a film thickness direction of said active layer, said second semiconductor layer, and said third semiconductor layer.

7. A semiconductor light emitting device according to claim 6, wherein a resonance wavelength of said resonator is a wavelength which renders photo luminescence light intensity maximum.

8. A semiconductor light emitting device according to claim 6, wherein said active layer is formed of any of a multiple quantum well layer having a multi-layered structure of a first layer made of GaN or InGaN and a second layer made of AlGaInN or GaN or InGaN, a GaN single layer, an InGaN single layer, and an AlGaInN single layer.

9. A semiconductor light emitting device according to claim 6, wherein said principal plane of said crystal substrate is a {11 20} plane or a {1100} plane of an SiC substrate, or a {1 102} plane of a sapphire substrate.

10. A semiconductor light emitting device comprising:

a first barrier layer formed of a first conductive type AlGaN which is deposited on an SiC substrate using a {1120} plane as a principal plane;

an active layer formed of a multiple quantum well layer including an InGaN layer, a multiple quantum well layer including an AlGaN layer, a GaN single layer, and an InGaN single layer, which is deposited on said first barrier layer, said active layer having a c axis exhibiting anisotropy along its face of a light emitted surface;

a second barrier layer formed of a second conductive type AlGaN which is deposited on said active layer;

an optical resonator formed in a film thickness direction, said optical resonator being formed by using a reflection mirror which is made of a multi-layered film provided on said second barrier layer as a first reflection surface and having a second reflection surface beneath said first barrier layer; and

a first electrode and a second electrode.

11. A light emitting diode comprising:

a second semiconductor layer formed on a principal plane of a wurtzite compound semiconductor crystal substrate via a first semiconductor layer;

an active layer formed on said second semiconductor layer and having an energy band gap which is smaller than an energy band gap of said second semiconductor layer, said active layer is made of a semiconductor having uniaxial anisotropy;

a third semiconductor layer formed on said active layer and having an energy band gap which is larger than an energy band gap of said active layer;

a pair of electrodes for supplying current to said second semiconductor, said active layer, and said third semiconductor layer in a film thickness direction; and

said film thickness direction of at least said active layer is different from an axis of said uniaxial anisotropy;

wherein a c axis of a wurtzite compound semiconductor crystal intersects substantially orthogonally with a light emission direction vertical to the substrate surface.

12. A light emitting diode according to claim 11, wherein said c axis of said wurtzite compound semiconductor crystal intersects substantially orthogonally with a crystal growth direction.

13. A light emitting diode according to claim 11, wherein said wurtzite compound semiconductor crystal is III-V compound semiconductor formed of III nitride.

14. A display device comprising:

a first group of light emitting diodes each formed of a wurtzite compound semiconductor crystal in which a light emission direction intersects substantially orthogonally with a c axis, said first group of light emitting diodes emitting light with a first polarization direction; and

a second group of light emitting diodes each formed of a wurtzite compound semiconductor crystal in which a light emission direction intersects substantially orthogonally with a c axis, said second group of light emitting diodes emitting light with a second polarization direction perpendicular to said first polarization direction.

15. A semiconductor light emitting device comprising:

a second semiconductor layer formed directly on a principal plane of a crystal substrate;

an active layer formed on said second semiconductor layer and having an energy band gap which is smaller than an energy band gap of said second semiconductor layer, and active layer is made of semiconductor having uniaxial anisotropy;

a third semiconductor layer formed on said active layer and having an energy band gap which is larger than an energy band gap of said active layer; and

a pair of electrodes for supplying current to said second semiconductor layer, said active layer, and said third semiconductor layer in a film thickness direction;

wherein said film thickness direction of at least said active layer is different from an axis of said uniaxial anisotropy, said active layer has triaxis anisotropy by applying distortion in a plane which is not perpendicular to a c axis exhibiting anisotropy, and light is emitted vertically relative to said principal plane.

16. A semiconductor light emitting device according to claim 15, wherein said semiconductor of active layer is wurtzite nitride.

17. A semiconductor light emitting device according to claim 15, wherein said substrate is made of GaN, AlN or SiC, and

said principal plane is a {1100} plane, a {1120} plane or a plane of said substrate inclined at -5 to +5 degree with said {1100} plane or said {1120} plane.

18. A semiconductor light emitting device according to claim 15, wherein said crystal substrate is formed of a LiAlO₂ substrate,

said principal plane is either a {100} plane or face inclined at an angle of -5 to +5 degree with said {100} face.

19. A semiconductor light emitting device according to claim 15, wherein said active layer is formed of Al_x Ga_l-x-y In_y N (where 0≦

x≦

1 and 0≦

y≦

1).

20. A semiconductor light emitting device according to claim 15, furthermore comprising

a mirror layer formed beneath said second semiconductor layer or on said third semiconductor layer, and

a resonator formed using said mirror layer as one end surface in a film thickness direction of said active layer, said second semiconductor layer, and said third semiconductor layer.

21. A semiconductor light emitting device according to claim 20, wherein a resonance wavelength of said resonator is a wavelength which renders photo luminescence light intensity maximum.

22. A semiconductor light emitting device according to claim 20, wherein said active layer is formed of any of a multiple quantum well layer having a multi-layered structure of a first layer made of GaN or InGaN and a second layer made of AlGaInN or GaN or InGaN, a GaN single layer, an InGaN single layer, and an AlGaInN single layer.

23. A semiconductor light emitting device according to claim 20, wherein said principal plane of said crystal substrate is a {1120} plane or a {1100} plane of an SiC substrate, or a {1102} plane of a sapphire substrate.

24. A semiconductor light emitting device comprising:

a second semiconductor layer formed directly on a principal plane of a crystal substrate via a first semiconductor layer;

an active layer formed on said second semiconductor layer and having an energy band gap which is smaller than an energy band gap of said second semiconductor layer, said active layer is made of semiconductor having uniaxial anisotropy;

a third semiconductor layer formed on said active layer and having an energy band gap which is larger than an energy band gap of said active layer; and

,

a pair of electrodes for supplying current to said second semiconductor layer, said active layer, and said third semiconductor layer in a film thickness direction,

wherein said film thickness direction of at least said active layer is different from an axis of said uniaxial anisotropy, said active layer has triaxis anisotropy by applying distortion in a plane which is not perpendicular to a c axis exhibiting anisotropy.

25. A semiconductor light emitting device according to claim 24, wherein said semiconductor of active layer is wurtzite nitride.

26. A semiconductor light emitting device according to claim 24, wherein said crystal substrate is made of GaN, AlN or SiC, and

said principal plane is a {1100} plane, a {1120} plane or a plane of said substrate inclined at -5 to +5 degree with said {1100} plane or said {1120} plane.

27. A semiconductor light emitting device according to claim 24, wherein said crystal substrate is formed of a LiAlO₂ substrate,

said principal plane is either a {100} plane or face inclined at an angle of -5 to +5 degree with said {100} face.

28. A semiconductor light emitting device according to claim 24, wherein said active layer is formed of Al_x Ga_l-x-y In_y N (where 0≦

y≦

1).

29. A semiconductor light emitting device according to claim 24, wherein said crystal substrate, said second semiconductor layer, said third semiconductor layer, and said active layer are cleaved along one of a {0001} plane, a {1100} plane and a {1120} plane.

30. A semiconductor light emitting device according to claim 24, wherein said principal plane of said crystal substrate is a facet with face orientation intersecting with {0001} plane, and said active layer formed on said facet is used as a light emitting portion.

31. A semiconductor light emitting device according to claim 30, wherein said facet is formed to have a face orientation perpendicular to either a {1100} plane or {1120} plane or a {0001} plane, and said {1100} plane or said {1120} plane or said {0001} plane is a cleavage plane on both ends of a resonator.

32. A semiconductor light emitting device according to claim 24, wherein the thickness of said active layer is 1-20 nm.

33. A semiconductor light emitting device comprising:

a second semiconductor layer formed directly on a principal plane of a crystal substrate;

an active layer formed on said second semiconductor layer and having an energy band gap which is smaller than an energy band gap of said second semiconductor layer, said active layer is made of semiconductor having uniaxial anisotropy;

a third semiconductor layer formed on said active layer and having an energy band gap which is larger than an energy band gap of said active layer; and

a pair of electrodes for supplying current to said second semiconductor layer, said active layer, and said third semiconductor layer in a film thickness direction;

wherein said film thickness direction of at least said active layer is different from an axis of said uniaxial anisotropy, said active layer has triaxis anisotropy by applying distortion in a plane which is not perpendicular to a c axis exhibiting anisotropy.

34. A semiconductor light emitting device according to claim 33, wherein said semiconductor of active layer is wurtzite nitride.

35. A semiconductor light emitting device according to claim 33, wherein said substrate is made of GaN, AlN or SiC, and

said principal plane is a {1100} plane, a {1120} plane or a plane of said substrate inclined at -5 to +5 degree with said {1100} plane or said {1120} plane.

36. A semiconductor light emitting device according to claim 33, wherein said crystal substrate is formed of a LiAlO₂ substrate,

said principal plane is either a {100} plane or face inclined at an angle of -5 to +5 degree with said {100} face.

37. A semiconductor light emitting device according to claim 33, wherein said active layer is formed of Al_x Ga_l-x-y In_y N (where 0≦

x≦

1 and 0≦

y≦

1).

38. A semiconductor light emitting device according to claim 33, wherein said crystal substrate, said second semiconductor layer, said third semiconductor layer, and said active layer are cleaved along one of a {0001} plane, a {1100} plane and a {1120} plane.

39. A semiconductor light emitting device according to claim 33, wherein said principal plane of said crystal substrate is a facet with face orientation intersecting with a {0001} plane, and said active layer formed on said facet is used as a light emitting portion.

40. A semiconductor light emitting device according to claim 39, wherein said facet is formed to have face orientation perpendicular to either a {1100} plane or a {1120} plane or a {0001} plane, and said {1100} or said {1120} plane or said {0001} is a cleavage plane on both ends of a resonator.

41. A semiconductor light emitting device according to claim 33, wherein the thickness of said active layer is 1-20 nm.