Graphene on Semiconductor Detector

• US 20130082241A1
• Filed: 09/28/2012
• Published: 04/04/2013
• Est. Priority Date: 09/29/2011
• Status: Active Grant

• Current Assignee: The Government Of The United States Of America, As Represented By The Secretary Of The Navy
• Original Assignee: The Government Of The United States Of America, As Represented By The Secretary Of The Navy
• Inventors: Kub, Francis J., Anderson, Travis, Hobart, Karl D.
• Granted Patent: US 8,872,159 B2
• Time in Patent Office: Days
• US Class Current: 257/21
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 27/14692 Thin film technologies, e.g. amorphous, poly, micro- or nanocrystalline silicon
• CPC Class Codes: H01L 27/14694 The active layers comprising only AIIIBV compounds, e.g. GaAs, InP
• CPC Class Codes: H01L 27/148 Charge coupled imagers individual charge coupled devices H01L29/765
• CPC Class Codes: H01L 31/028 including, apart from doping material or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/0336 in different semiconductor regions, e.g. Cu2X/CdX hetero- junctions, X being an element of Group VI of the Periodic Table

Abstract

Ultraviolet or Extreme Ultraviolet and/or visible detector apparatus and fabrication processes are presented, in which the detector includes a thin graphene electrode structure disposed over a semiconductor surface to provide establish a potential in the semiconductor material surface and to collect photogenerated carriers, with a first contact providing a top side or bottom side connection for the semiconductor structure and a second contact for connection to the graphene layer.

Claims

1. A detector apparatus, comprising:

a semiconductor structure with a first surface;

a graphene layer disposed over at least a portion of the first surface of the semiconductor structure and having an upper surface with a first portion configured to collect photogenerated carriers and to establish a potential on the first surface of the semiconductor structure;

a first contact structure electrically connected to the semiconductor structure; and

a second contact structure electrically connected to a second portion of the upper surface of the graphene layer.

2. The apparatus of claim 1, wherein the graphene layer has a thickness of about 0.3 nm or more.

3. The apparatus of claim 1, wherein the graphene layer is a single atomic layer of carbon atoms forming a substantially two-dimensional honeycomb crystal lattice over the first surface of the semiconductor structure.

4. The apparatus of claim 1, wherein the first and second contact structures are formed on a top side of the apparatus.

5. The apparatus of claim 4, wherein the semiconductor structure is of a first conductivity type and comprises an implanted or epitaxially grown region having a dopant concentration of the first conductivity type greater than a dopant concentration of the remainder of the semiconductor structure, wherein the first contact structure is an ohmic metal contact formed over at least a portion of an upper surface of the implanted or epitaxially grown region of the semiconductor structure.

6. The apparatus of claim 4, wherein the first contact structure is a Schottky metal contact formed over a portion of the first surface of the semiconductor structure, wherein the first contact structure is laterally spaced from the graphene layer.

7. The apparatus of claim 4, comprising:

a plurality of detector cells spaced from one another on the top side of the apparatus, with individual detector cells including;

a graphene layer disposed over the first surface of the semiconductor structure, the graphene layer having and a thickness of about 3.0 nm or less and an upper surface with a first portion configured to collect photogenerated carriers and to establish a potential on the first surface of the semiconductor structure,

a first contact structure electrically connected to the semiconductor structure, and

a second contact structure formed on a second portion of the upper surface of the graphene layer; and

at least one isolation structure separating first and second detector cells from one another.

8. The apparatus of claim 4, comprising a support substrate disposed along at least a portion of a bottom side of the semiconductor structure.

9. The apparatus of claim 8, comprising a semiconductor epitaxial nucleation layer formed on a top side of the support substrate, wherein the semiconductor structure comprises an epitaxially grown semiconductor material formed over the nucleation layer.

10. The apparatus of claim 1, wherein the first contact structure is formed on a bottom side of the semiconductor structure, and the second contact structure is formed on a top side of the apparatus.

11. The apparatus of claim 10, comprising:

a plurality of detector cells laterally spaced from one another, with individual detector cells including;

a semiconductor structure of a first conductivity type, including an implanted lower region having a dopant concentration of the first conductivity type greater than a dopant concentration of the remainder of the semiconductor structure,

a graphene layer disposed over an upper surface of the semiconductor structure, the graphene layer having and a thickness of about 3.0 nm or less and an upper surface with a first portion configured to collect photogenerated carriers and to establish a potential on the first surface of the semiconductor structure,

a first contact structure electrically connected to the semiconductor structure, wherein the first contact structure is an ohmic metal contact formed over at least a portion of a lower surface of the implanted region of the semiconductor structure,

an indium structure disposed along at least a portion of a bottom surface of the first contact structure, and

a second contact structure formed on a second portion of the upper surface of the graphene layer; and

at least one isolation structure separating lateral sides of the semiconductor structures of first and second detector cells from one another.

12. The apparatus of claim 11, wherein the at least one isolation structure comprises a deep level trap region of the semiconductor structure implanted with protons or oxygen.

13. The apparatus of claim 11, wherein the at least one isolation structure comprises an implanted region of a second conductivity type in the semiconductor structure.

14. The apparatus of claim 10, comprising:

a plurality of detector cells laterally spaced from one another, with individual detector cells including;

a semiconductor structure of a first conductivity type,

a graphene layer disposed over an upper surface of the semiconductor structure, the graphene layer having and a thickness of about 3.0 nm or less and an upper surface with a first portion configured to collect photogenerated carriers and to establish a potential on the first surface of the semiconductor structure,

a first contact structure electrically connected to the semiconductor structure, wherein the first contact structure is a Schottky metal contact formed over at least a portion of a lower surface of the semiconductor structure,

an indium structure disposed along at least a portion of a bottom surface of the first contact structure, and

a second contact structure formed on a second portion of the upper surface of the graphene layer; and

at least one isolation structure separating lateral sides of the semiconductor structures of first and second detector cells from one another.

15. The apparatus of claim 14, wherein the at least one isolation structure comprises a deep level trap region of the semiconductor structure implanted with protons or oxygen.

16. The apparatus of claim 14, wherein the at least one isolation structure comprises an implanted region of a second conductivity type in the semiconductor structure.

17. The apparatus of claim 10, comprising at least one of an upper support substrate disposed over a portion of the upper surface of the graphene layer, and a lower support substrate disposed along the lower side of the apparatus.

18. The apparatus of claim 10, wherein the semiconductor structure comprises silicon carbide.

19. The apparatus of claim 10, wherein the semiconductor structure comprises aluminum gallium nitride.

20. The apparatus of claim 1, wherein the semiconductor structure has a bandgap more than 2.5 electron volts.

21. The apparatus of claim 1, wherein the graphene layer has a thickness of about 3.0 nm or less.

22. The apparatus of claim 1, wherein the second contact structure and the first contact structure have the about the same voltage.

23. The apparatus of claim 1, wherein the first contact structure is electrically connected to the semiconductor structure via a CMOS transfer transistor.

24. A method of making a detector, the method comprising:

forming a graphene layer over a first surface of a semiconductor structure to a thickness of about 3.0 nm or less, the graphene layer comprising first and second portions;

forming a first contact structure electrically connected to the semiconductor structure; and

forming a second contact structure on the second portion of the upper surface of the graphene layer.

25. An active pixel sensor apparatus, comprising:

a semiconductor structure with a first surface;

at least one pixel detector, comprising a graphene layer disposed over at least a portion of the first surface of the semiconductor structure, the graphene layer including a sensing surface configured to collect photogenerated carriers and adapted to establish a potential at the first surface of the semiconductor structure;

a transfer transistor including;

a source formed in the semiconductor structure,

a control gate, and

a drain electrically coupled with a readout circuit operative to read data from the at least one pixel detector using the control gate; and

a reset transistor formed in the semiconductor structure and operative to selectively remove charge from the at least one pixel detector.

26. The active pixel sensor apparatus of claim 25, comprising a coating layer formed over at least a portion of the sensing surface of the graphene layer.

27. The active pixel sensor apparatus of claim 26, wherein the coating layer is at least one of a protective layer, an anti-reflectance material, a filter, a neutron conversion layer, and a micro lens.

28. The active pixel sensor apparatus of claim 25, wherein the at least one pixel detector is operative to detect ultraviolet light.

29. The active pixel sensor apparatus of claim 25, wherein the at least one pixel detector is operative to detect visible light.

30. A charge coupled device (CCD), comprising:

a semiconductor structure with a first surface;

at least one pixel detector, comprising a graphene layer disposed over at least a portion of the first surface of the semiconductor structure, the graphene layer including a sensing surface facing a backside of the CCD;

a transfer transistor including a source formed in the semiconductor structure, and a drain electrically coupled with a readout circuit operative to read data from the at least one pixel detector.

31. The CCD of claim 30, wherein the at least one pixel detector is operative to detect visible light.