Semiconductor structure with chirp layer

Patent metadata

Field	Value
Publication number	US-10978611-B2
Application number	US-202017062369-A
Country	US
Kind code	B2
Filing date	Oct 2, 2020
Priority date	Apr 6, 2018
Publication date	Apr 13, 2021
Grant date	Apr 13, 2021

Abstract

A semiconductor structure can comprise a plurality of first semiconductor layers comprising wide bandgap semiconductor layers, a narrow bandgap semiconductor layer, and a chirp layer between the plurality of first semiconductor layers and the narrow bandgap semiconductor layer. The values of overlap integrals between different electron wavefunctions in a conduction band of the chirp layer can be less than 0.05 for intersubband transition energies greater than 1.0 eV, and/or the values of overlaps between electron wavefunctions and barrier centers in a conduction band of the chirp layer can be less than 0.3 nm−1, when the structure is biased at an operating potential. The chirp layer can comprise a short-period superlattice with alternating wide bandgap barrier layers and narrow bandgap well layers, wherein the thickness of the barrier layers, or the well layers, or the thickness of both the barrier and well layers changes throughout the chirp layer.

First claim

What is claimed is:

1. A semiconductor structure comprising:
a plurality of first semiconductor layers comprising wide bandgap semiconductor layers;
a narrow bandgap semiconductor layer; and
a chirp layer between the plurality of first semiconductor layers and the narrow bandgap semiconductor layer;
wherein:
the plurality of first semiconductor layers comprise an n-type short-period superlattice layer (SPSL) and an unintentionally doped SPSL between the n-type SPSL and the chirp layer; and
values of overlap integrals between different electron wavefunctions in a conduction band of the chirp layer are less than 0.05 for intersubband transition energies greater than 1.0 eV, when the structure is biased at an operating potential.

2. The semiconductor structure of claim 1 , wherein the chirp layer is unintentionally doped.

3. The semiconductor structure of claim 1 , wherein the chirp layer has a high hole concentration due to polarization doping.

4. The semiconductor structure of claim 1 , wherein:
the n-type short-period superlattice layer (SPSL), the unintentionally doped SPSL, and the chirp layer comprise alternating layers of GaN and AlN; and
the narrow bandgap semiconductor layer comprises p-type GaN.

5. The semiconductor structure of claim 4 , wherein:
the AlN layers in the chirp layer have thicknesses that are from 2 monolayers to greater than 10 monolayers; and
the GaN layers in the chirp layer have thicknesses that are varied from less than 1 monolayer in a region nearest the unintentionally doped short-period superlattice layer to greater than 10 monolayers in a region nearest the narrow bandgap semiconductor layer.

6. The semiconductor structure of claim 5 , wherein:
the AlN layers in the chirp layer have thicknesses that are varied from greater than 10 monolayers in the region nearest the unintentionally doped short-period superlattice layer to less than 1 monolayer in the region nearest the narrow bandgap semiconductor layer.

7. The semiconductor structure of claim 1 , wherein the operating potential is within 1 V of a flatband condition.

8. The semiconductor structure of claim 1 , further comprising an electron blocking layer between the plurality of first semiconductor layers and the chirp layer.

9. A semiconductor device incorporating the semiconductor structure of claim 1 , wherein the semiconductor device is selected from the group consisting of light emitting diodes (LEDs), short wavelength LEDs, UV-C LEDs, UV-A LEDs, bipolar junction transistors, power transistors, vertical field-effect transistors, and semiconductor lasers.

10. A semiconductor structure comprising:
a plurality of first semiconductor layers comprising wide bandgap semiconductor layers;
a narrow bandgap semiconductor layer; and
a chirp layer between the plurality of first semiconductor layers and the narrow bandgap semiconductor layer;
wherein:
the plurality of first semiconductor layers comprise an n-type short-period superlattice layer (SPSL) and an unintentionally doped SPSL between the n-type SPSL and the chirp layer; and
values of overlaps between electron wavefunctions and barrier centers in a conduction band of the chirp layer are less than 0.3 nm −1 , when the structure is biased at an operating potential.

11. The semiconductor structure of claim 10 , wherein the chirp layer is unintentionally doped.

12. The semiconductor structure of claim 10 , wherein the chirp layer has a high hole concentration due to polarization doping.

13. The semiconductor structure of claim 10 , wherein:
the n-type short-period superlattice layer (SPSL), the unintentionally doped SPSL, and the chirp layer comprise alternating layers of GaN and AlN; and
the narrow bandgap semiconductor layer comprises p-type GaN.

14. The semiconductor structure of claim 13 , wherein:
the AlN layers in the chirp layer have thicknesses that are from 2 monolayers to greater than 10 monolayers; and
the GaN layers in the chirp layer have thicknesses that are varied from less than 1 monolayer in a region nearest the unintentionally doped short-period superlattice layer to greater than 10 monolayers in a region nearest the narrow bandgap semiconductor layer.

15. The semiconductor structure of claim 14 , wherein:
the AlN layers in the chirp layer have thicknesses that are varied from greater than 10 monolayers in the region nearest the unintentionally doped short-period superlattice layer to less than 1 monolayer in the region nearest the narrow bandgap semiconductor layer.

16. The semiconductor structure of claim 10 , wherein the operating potential is within 1 V of a flatband condition.

17. The semiconductor structure of claim 10 , further comprising an electron blocking layer between the plurality of first semiconductor layers and the chirp layer.

18. A semiconductor device incorporating the semiconductor structure of claim 10 , wherein the semiconductor device is selected from the group consisting of light emitting diodes (LEDs), short wavelength LEDs, UV-C LEDs, UV-A LEDs, bipolar junction transistors, power transistors, vertical field-effect transistors, and semiconductor lasers.

19. A semiconductor structure comprising:
a plurality of first semiconductor layers comprising wide bandgap semiconductor layers;
a narrow bandgap semiconductor layer; and
an unintentionally doped chirp layer between the plurality of first semiconductor layers and the narrow bandgap semiconductor layer;
wherein:
the plurality of first semiconductor layers comprise an n-type short-period superlattice layer (SPSL) and an unintentionally doped SPSL between the n-type SPSL and the unintentionally doped chirp layer; and
the unintentionally doped chirp layer comprises a SPSL with alternating wide bandgap barrier layers and narrow bandgap well layers, wherein the thicknesses of the wide bandgap barrier layers, or the thicknesses of the narrow bandgap well layers, or the thicknesses of both the wide bandgap barrier layers and the narrow bandgap well layers, change throughout the chirp layer.

20. The semiconductor structure of claim 19 , wherein the thicknesses of the wide bandgap barrier layers are from 2 monolayers to greater than 10 monolayers.

21. The semiconductor structure of claim 19 , wherein:
the n-type short-period superlattice layer (SPSL), the unintentionally doped SPSL, and the unintentionally doped chirp layer comprise alternating layers of GaN and AlN; and
the narrow bandgap semiconductor layer comprises p-type GaN.

22. The semiconductor structure of claim 21 , wherein:
the AlN layers in the unintentionally doped chirp layer have thicknesses that are from 2 monolayers to greater than 10 monolayers; and
the GaN layers in the unintentionally doped chirp layer have thicknesses that are varied from less than 1 monolayer in a region nearest the unintentionally doped short-period superlattice layer to greater than 10 monolayers in a region nearest the narrow bandgap semiconductor layer.

23. The semiconductor structure of claim 22 , wherein:
the AlN layers in the unintentionally doped chirp layer have thicknesses that are varied from greater than 10 monolayers in the region nearest the unintentionally doped short-period superlattice layer to less than 1 monolayer in the region nearest the narrow bandgap semiconductor layer.

24. The semiconductor structure of claim 19 , further comprising an electron blocking layer between the plurality of first semiconductor layer

Assignees

• Silanna UV Technologies Pte Ltd

Inventors

• Krause Norbert
• Tosi Guilherme

Classifications

• H10D62/8503

  Nitride Group III-V materials, e.g. AlN or GaN · CPC title

• H10D62/8161

  potential variation due to variations in composition or crystallinity, e.g. heterojunction superlattices (lateral superlattices, lateral surface superlattices H10D62/8181) · CPC title

• H10H20/825 Primary

  containing nitrogen, e.g. GaN · CPC title

• H10H20/811 Primary

  having quantum effect structures or superlattices, e.g. tunnel junctions · CPC title

• H10H20/812

  within the light-emitting regions, e.g. having quantum confinement structures · CPC title