A SINGLE-PHOTON DETECTOR WITH A QUANTUM DOT AND A NANO-INJECTOR

• US 20100123120A1
• Filed: 09/27/2006
• Published: 05/20/2010
• Est. Priority Date: 09/27/2005
• Status: Active Grant

• Current Assignee: Northwestern University
• Original Assignee: Northwestern University
• Inventors: Mohseni, Hooman
• Granted Patent: US 7,745,816 B2
• Time in Patent Office: Days
• US Class Current: 257/21
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers

Abstract

A semiconductor photodetector for photon detection without the use of avalanche multiplication, and capable of operating at low bias voltage and without excess noise. In one embodiment, the photodetector comprises a plurality of InP/AlInGaAs/AlGaAsSb layers, capable of spatially separating the electron and the hole of an photo-generated electron-hole pair in one layer, transporting one of the electron and the hole of the photo-generated electron-hole pair into another layer, focalizing it into a desired volume and trapping it therein, the desired volume having a dimension in a scale of nanometers to reduce its capacitance and increase the change of potential for a trapped carrier, and a nano-injector, capable of injecting carriers into the plurality of InP/AlInGaAs/AlGaAsSb layers, where the carrier transit time in the nano-injector is much shorter than the carrier recombination time therein, thereby causing a very large carrier recycling effect.

Claims

1. A single-photon detector, comprising:

(a) a photon absorption layer for generating an electron-hole pair responsive to an incident photon thereto;

(b) a first carrier barrier layer formed on the photon absorption layer;

(c) a carrier mobile layer formed on the first carrier barrier layer;

(d) a second carrier barrier layer formed on the carrier mobile layer to have a carrier barrier region and an oxidized region surrounding the carrier barrier region, the carrier barrier region having a dimension, d, in a scale of nanometers, wherein the carrier mobile layer and the first and second carrier barrier layers are configured to form a first energy band structure having a quantum well in the carrier mobile layer;

(e) a first conductive element in contact with the second carrier barrier layer and positioned over the carrier barrier region of the second carrier barrier layer to form a nano-injector therewith for injecting electrons, which in turn, defines a quantum dot in the carrier mobile layer directly under the nano-injector which is capable of trapping the hole of the photo-generated electron-hole pair while regulating an electron flow through the nano-injector;

(f) a second conductive element in contact with at least the photon absorption layer; and

(g) a power source electrically coupled to the first conductive element and the second conductive element.

3. The single-photon detector of claim 1, being configured such that when a voltage is applied between the first conductive element and the second conductive element from the power source, an electric field is established with a lateral component and a vertical component and a stream of electrons flows through the nano-injector from the first conductive element, and wherein the lateral component of the electric field causes the hole to move towards the quantum dot underneath the nano-injector and be trapped therein, wherein the presence of the trapped hole in the quantum dot in turn, enhances a rate of the stream of electrons tunneling through the quantum dot into the photon absorption layer, thereby resulting in a measurable increase of a corresponding electric current.

4. The single-photon detector of claim 3, wherein each of the stream of electrons moves towards to the second conductive element from the first conductive element unless it is recombined with the trapped hole in the volume, or until the trapped hole is thermally exited and leaves the volume.

5. The single-photon detector of claim 3, wherein the stream of electrons is augmented in a limited region of the photon absorption layer after tunneling through the quantum dot, and wherein the limited region of the photon absorption layer is located under the quantum dot.

6. The single-photon detector of claim 3, wherein the trapped hole in the quantum dot has a lifetime, τ

_h, wherein the stream of electrons has a transition time, τ

_trans, for tunneling through the quantum dot, and wherein τ

_h>

>

τ

_trans.

7. The single-photon detector of claim 1, wherein the carrier mobile layer is made from a hole transporting material, and wherein each of the first and second carrier barrier layers is made from an electron barrier material.

8. The single-photon detector of claim 7, wherein the first carrier barrier layer is made from a semiconductor material.

9. The single-photon detector of claim 8, wherein the second carrier barrier layer is made from a semiconductor material that is same as or different from the semiconductor material of the first carrier barrier layer.

10. The single-photon detector of claim 1, wherein the photon absorption layer is made from a semiconductor material.

11. The single-photon detector of claim 1, further comprising a substrate on which the photon absorption layer is formed.

12. The single-photon detector of claim 11, wherein the substrate is made from one of a semiconductor material, a metallic material and an insulating material.

13. The single-photon detector of claim 1, wherein the dimension d of the carrier barrier region of the second carrier barrier layer is in a range of about 1-500 nm, preferably in a range of about 10-200 nm.

2. (canceled)

14-46. -46. (canceled)

47. A nano-transistor, comprising:

(a) a photon absorption member; and

(b) a carrier injecting member having a first layer formed on the photon absorption member and a second layer formed on the first layer and adapted for injecting carriers from the second layer into the photon absorption member, wherein the carrier injecting member has a horizontal dimension in a scale of nanometers,

wherein the photon absorption member and the first and second layers are configured to have an energy band structure that defines a quantum dot in the first layer, such that when a photon is incident to the photon absorption member, an electron-hole pair is generated therein responsively, and one of the electron and hole of the photo-generated electron-hole pair is transported and trapped into the quantum dot in the first layer so as to enhance the concentration of the corresponding carrier therein, thereby enhancing a rate of injected carriers tunneling through the quantum dot in the first layer into the photon absorption member, wherein the injected carriers are complementary to the corresponding carrier trapped in the quantum dot.

48. The nano-transistor of claim 47, wherein the photon absorption member has a dimension in a scale of micrometers.

49. An array formed with a plurality of nano-transistors of claim 47.

50. A nano-resonator, comprising:

(a) a photon absorption member; and

(b) a carrier injecting member having a first layer formed on the photon absorption member, a second layer formed on the first layer, a third layer formed on the second layer, and a fourth layer formed on the third layer, and adapted for injecting carriers from the fourth layer into the photon absorption member, wherein the carrier injecting member has a horizontal dimension in a scale of nanometers,

wherein the photon absorption member and the first to fourth layers are configured to have an energy band structure that defines a quantum dot in the second layer, such that when a photon is incident to the photon absorption member, an electron-hole pair is generated therein responsively, and one of the electron and hole of the photo-generated electron-hole pair is transported and trapped into the quantum dot in the second layer so as to enhance the concentration of the corresponding carrier therein, thereby enhancing a rate of injected carriers tunneling through the quantum dot in the second layer into the photon absorption member, wherein the injected carriers are complementary to the corresponding carrier trapped in the quantum dot.

52. An array formed with a plurality of nano-resonators of claim 50.

53-55. -55. (canceled)

56. A single-photon detector, comprising:

(a) a multilayer structure having a photon absorption layer and a carrier mobile layer formed on the photon absorption layer, the multilayer structure configured to form a quantum well in the carrier mobile layer, the photon absorption layer adapted for generating an electron-hole pair responsive to an incident photon thereto; and

(b) a nano-injector for injecting carriers, having a working end with a dimension in a scale of nanometers formed over the carrier mobile layer and configured to define a quantum dot in the carrier mobile layer directly under the nano-injector, the quantum dot being capable of trapping one type of carriers of electrons and holes while repelling the other type of carriers of electrons and holes,

wherein in operation, an electric field is established with a lateral component and a vertical component and a stream of injected carriers flows through the working end of the nano-injector, and wherein the lateral component of the electric field causes one of the electron and hole of the photo-generated electron-hole pair to move towards the quantum dot under the nano-injector and be trapped therein, wherein the presence of the trapped carrier in the quantum dot in turn, enhances a rate of the stream of injected carriers from the working end of the nano-injector tunneling through the quantum dot into the photon absorption layer, thereby resulting in a measurable increase of a corresponding electric current, wherein the injected carriers are complementary to the corresponding carrier trapped in the quantum dot.

51. The nano-resonator of claim 58, wherein the photon absorption member has a dimension in a scale of micrometers.

57. The single-photon detector of claim 56, wherein the trapped carrier in the quantum dot has a lifetime, τ

_h, wherein the stream of injected carriers has a transition time, τ

_trans, for tunneling through the quantum dot, and wherein τ

_h>

>

τ

_trans.

58. The single-photon detector of claim 57, wherein the trapped carrier in the quantum dot is corresponding to the hole of the photo-generated electron-hole pair, and wherein the injected carriers are corresponding to electrons.

59. The single-photon detector of claim 57, wherein the trapped carrier in the quantum dot is corresponding to the electron of the photo-generated electron-hole pair, and wherein the injected carriers are corresponding to holes.

60. An apparatus for single photon detection, comprising a plurality of single-photon detectors of claim 56, spatially arranged in an array.