Spectrometer including vertical stack structure and non-invasive biometric sensor including the spectrometer

Patent metadata

Field	Value
Publication number	US-9867544-B2
Application number	US-201514821933-A
Country	US
Kind code	B2
Filing date	Aug 10, 2015
Priority date	Nov 3, 2014
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

Provided are a spectrometer that may be easily manufactured while having high resolution and sensitivity due to reduced light loss and a non-invasive biometric sensor including the spectrometer. The spectrometer includes: a stacked light absorbing structure including a plurality of absorbing layers stacked in a vertical direction and having different absorption wavelength bands, and a plurality of tunnel junction layers respectively interposed between the plurality of absorbing layers to electrically connect the plurality of absorbing layers; and an illuminating unit configured to provide the stacked light absorbing structure with an illumination light for saturation of the plurality of absorbing layers.

First claim

What is claimed is:

1. A spectrometer comprising:
a stacked light absorbing structure comprising a plurality of absorbing layers stacked in a vertical direction and having a plurality of absorption wavelength bands, and a plurality of tunnel junction layers respectively interposed between the plurality of absorbing layers to electrically connect the plurality of absorbing layers;
a light source configured to generate an illumination light including the plurality of absorption wavelength bands of the plurality of absorbing layers;
a notch filter array disposed between the light source and the stacked light absorbing structure and comprising a plurality of notch filters having a plurality of absorption characteristics to block only a wavelength band selected from among the plurality of absorption wavelength bands; and
a controller configured to control the notch filter array to rotate according to a lapse of time to change, in a sequential order, the selected wavelength band to be blocked among the plurality of absorption wavelength bands.

2. The spectrometer of claim 1 , wherein
each of the plurality of notch filters has a sector shape, and
the notch filter array has a rotatable disk shape that is formed by connecting the plurality of notch filters on a rotation axis.

3. The spectrometer of claim 1 , wherein
each of the plurality of absorbing layers comprises a positive-negative (p-n) junction, and
each of the plurality of tunnel junction layers comprises a p-n junction that is doped at a higher doping concentration than the p-n junction of each of the plurality of absorbing layers.

4. The spectrometer of claim 1 , wherein
the plurality of absorbing layers are arranged in descending order of energy band gap from a light input side, and
each of the plurality of tunnel junction layers has a larger energy band gap than the plurality of absorbing layers.

5. The spectrometer of claim 1 , wherein the plurality of absorbing layers and the plurality of tunnel junction layers comprise a compound semiconductor.

6. The spectrometer of claim 5 , wherein the plurality of absorbing layers and the plurality of tunnel junction layers are formed of a material comprising any one selected from a combination comprising gallium arsenic phosphide (GaAsP), gallium arsenide (GaAs), and indium gallium arsenide (InGaAs), a combination comprising aluminum gallium arsenide (AlGaAs), GaAs, and InGaAs, a combination comprising InGaAs, GaAs, and gallium phosphide (GaP), and a combination comprising indium arsenide (InAs), GaAs, and gallium nitride (GaN).

7. The spectrometer of claim 1 , wherein
each of the plurality of absorbing layers has a thickness of about 10 nm to about 10 μm, and
each of the plurality of tunnel junction layers has a thickness of about 10 nm to about 100 nm.

8. The spectrometer of claim 1 , further comprising:
a first electrode disposed on a bottom surface of the stacked light absorbing structure; and
a second electrode disposed on a top surface of the stacked light absorbing structure,
wherein the plurality of absorbing layers are electrically connected in series between the first electrode and the second electrode.

9. The spectrometer of claim 8 , wherein
the first electrode is disposed on a bottom surface of an absorbing layer having the smallest energy band gap among the plurality of absorbing layers, and
the second electrode is disposed on a top surface of an absorbing layer having the largest energy band gap among the plurality of absorbing layers.

10. The spectrometer of claim 1 , wherein the controller is configured to obtain a photocurrent generated by the stacked light absorbing structure in response to the selected wavelength band to be blocked being changed.

11. The spectrometer of claim 10 , wherein the controller is configured to store a pre-measured external quantum efficiency or short-circuit current density of each of the plurality of absorbing layers.

12. A non-invasive biometric sensor comprising:
a spectrometer configured to obtain a spectrum distribution of a scattered light, which is generated from an object by an excitation light; and
a controller configured to control operations of the spectrometer and analyze properties of the object by using signals provided by the spectrometer,
the spectrometer comprising:
a stacked light absorbing structure comprising a plurality of absorbing layers stacked in a vertical direction and having a plurality of absorption wavelength bands, and a plurality of tunnel junction layers respectively interposed between the plurality of absorbing layers to electrically connect the plurality of absorbing layers;
a light source configured to generate an illumination light including the plurality of absorption wavelength bands of the plurality of absorbing layers; and

a notch filter array disposed between the light source and the stacked light absorbing structure and comprising a plurality of notch filters having a plurality of absorption characteristics to block only a wavelength band selected from among the plurality of absorption wavelength bands,
wherein the controller is configured to control the notch filter array to rotate according to a lapse of time to change, in a sequential order, the selected wavelength band to be blocked among the plurality of absorption wavelength bands.

13. The non-invasive biometric sensor of claim 12 , wherein
the scattered light and the illumination light are together input to a light input surface of the stacked light absorbing structure, and
the notch filter array is disposed only on a path of the illumination light.

14. The non-invasive biometric sensor of claim 12 , wherein the controller is configured to store a pre-measured external quantum efficiency or short-circuit current density of each of the plurality of absorbing layers.

15. The non-invasive biometric sensor of claim 14 , wherein the controller is configured to obtain a photocurrent generated by the stacked light absorbing structure in response to the selected wavelength band to be blocked being changed.

16. The non-invasive biometric sensor of claim 15 , wherein the controller is configured to calculate the spectrum distribution of the scattered light by using the pre-measured external quantum efficiency or short-circuit current density of each of the plurality of absorbing layers and photocurrent values of the stacked light absorbing structure that are obtained in response to the selected wavelength band to be blocked being changed.

17. The non-invasive biometric sensor of claim 12 , further comprising a signal processor configured to analyze the properties of the object based on the spectrum distribution of the scattered light.

18. A non-invasive biometric sensing method comprising:
radiating an excitation light to an object;
providing a scattered light, which is generated from the object by the excitation light, to a stacked light absorbing structure, the stacked light absorbing structure comprising first to Nth absorbing layers stacked in a vertical direction and having different first to Nth absorption wavelength bands, and a plurality of tunnel junction layers respectively interposed between the first to Nth absorbing layers to electrically connect the first to Nth absorbing layers;
providing the stacked light absorbing structure with an illumination light for saturation of the second to Nth absorbing layers, other than the first absorbing layer, together with the providing of the scattered light, by using a notch filter array to block only the first absorption wavelength band sel

Assignees

• Samsung Electronics Co Ltd

Inventors

• Kim Dongho

Classifications

• G01J3/0205 Primary

  Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows · CPC title

• G01J3/51

  using colour filters · CPC title

• G01J3/44

  Raman spectrometry; Scattering spectrometry {; Fluorescence spectrometry} · CPC title

• G01J3/0227 Primary

  using notch filters · CPC title

• A61B5/0075 Primary

  by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy (A61B5/0071 takes precedence) · CPC title