Quantum cascade detector

Patent metadata

Field	Value
Publication number	US-9929292-B2
Application number	US-201715423836-A
Country	US
Kind code	B2
Filing date	Feb 3, 2017
Priority date	Feb 18, 2016
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

A quantum cascade detector includes a semiconductor substrate; an active layer having a cascade structure; a lower cladding layer provided between the active layer and the substrate and having a lower refractive index than the active layer; a lower metal layer provided between the lower cladding layer and the substrate; an upper cladding layer provided on an opposite side to the substrate with respect to the active layer and having a lower refractive index than the active layer; and an upper metal layer provided on an opposite side to the active layer with respect to the upper cladding layer. A first end face being in a waveguide direction in a waveguide structure with the active layer, lower cladding layer, and upper cladding layer is an entrance surface for light to be detected.

First claim

What is claimed is:

1. A quantum cascade detector comprising:
a semiconductor substrate;
an active layer provided on the semiconductor substrate and having a cascade structure in which absorption regions and transport regions are alternately stacked in the form of a multistage lamination of unit laminate structures each of which comprises n (where n is an integer of 3 or more) quantum well layers including a first well layer serving as an absorption well layer and n quantum barrier layers, the absorption region including the first well layer and detecting light to be detected by intersubband absorption, the transport region transporting electrons excited by the intersubband absorption;
a lower cladding layer provided between the active layer and the semiconductor substrate and having a lower refractive index than the active layer;
a lower metal layer provided between the lower cladding layer and the semiconductor substrate;
an upper cladding layer provided on an opposite side to the semiconductor substrate with respect to the active layer and having a lower refractive index than the active layer; and
an upper metal layer provided on an opposite side to the active layer with respect to the upper cladding layer, wherein
a waveguide structure is configured with the active layer, the lower cladding layer, and the upper cladding layer so as to guide the light to be detected along the active layer, and the waveguide structure is sandwiched by the lower metal layer and the upper metal layer, and
of a first end face and a second end face being in a waveguide direction of the light to be detected in the waveguide structure, the first end face including cross sections of the active layer, the lower cladding layer, and the upper cladding layer is an entrance surface from which the light to be detected enters.

2. The quantum cascade detector according to claim 1 , wherein each of the lower cladding layer and the upper cladding layer has a layer thickness of 2 μm or more and 10 μm or less.

3. The quantum cascade detector according to claim 1 , wherein the active layer has a layer thickness of 1 μm or more.

4. The quantum cascade detector according to claim 1 , wherein each of the lower cladding layer and the upper cladding layer has a doping density of impurities of 5×10 16 cm −3 or more and 2×10 17 cm −3 or less.

5. The quantum cascade detector according to claim 1 , wherein the active layer has a doping density of impurities of 1×10 17 cm −3 or more and 9×10 17 cm −3 or less.

6. The quantum cascade detector according to claim 1 , being configured in a mesa structure having a base portion including the semiconductor substrate; and a mesa portion provided on the base portion, including the active layer, and extending in a stripe shape in the waveguide direction in the waveguide structure.

7. The quantum cascade detector according to claim 1 , wherein an antireflection film for reducing reflectance for the light to be detected is formed on the first end face in the waveguide structure.

8. The quantum cascade detector according to claim 1 , wherein a reflection film for increasing reflectance for the light to be detected is formed on the second end face in the waveguide structure, and the second end face is a reflection surface for the light to be detected.

9. The quantum cascade detector according to claim 1 , wherein a light receiving area in the entrance surface is limited to the cross sections of the active layer, the lower cladding layer, and the upper cladding layer by the lower metal layer and the upper metal layer.

Assignees

• Hamamatsu Photonics Kk

Inventors

• Dougakiuchi Tatsuo
• Ito Akio
• Edamura Tadataka
• Fujita Kazuue

Classifications

• H01L31/02161

  Electricity · mapped topic

• H01L31/03042

  Electricity · mapped topic

• H01L31/03046

  Electricity · mapped topic

• H01L31/035281

  Electricity · mapped topic

• H01L31/02327

  Electricity · mapped topic