Multiband double junction photodiode and related manufacturing process

Patent metadata

Field	Value
Publication number	US-9685575-B2
Application number	US-201514640663-A
Country	US
Kind code	B2
Filing date	Mar 6, 2015
Priority date	Mar 6, 2015
Publication date	Jun 20, 2017
Grant date	Jun 20, 2017

Abstract

A photodiode structure is based on the use of a double junction sensitive to different wavelength bands based on a magnitude of a reverse bias applied to the photodiode. The monolithic integration of a sensor with double functionality in a single chip allows realization of a low cost ultra-compact sensing element in a single packaging useful in many applications which require simultaneous or spatially synchronized detection of optical photons in different spectral regions.

First claim

The invention claimed is:

1. A device, comprising:
a photodiode, the photodiode including:
a first layer of semiconductor material;
a second layer of semiconductor material on the first layer of semiconductor material;
a first contact on the first layer of semiconductor material;
a second contact on the second layer of semiconductor material;
a first photodiode junction at a first interface of the first contact and the first layer of semiconductor material;
a second photodiode junction at a second interface of the second contact and the second layer of semiconductor material;
a first electrode electrically coupled to the first layer of semiconductor material; and
a second electrode electrically coupled to the first and second contacts, in response to a first selected voltage applied between the first and second electrodes the photodiode is sensitive to light in a first wavelength band and substantially insensitive to light in a second wavelength band, and in response to a second selected voltage applied between the first and second electrodes the photodiode is sensitive to light in the second wavelength band.

2. The device of claim 1 , further comprising an aperture in the second electrode, the second electrode being positioned on the second contact, the aperture being configured to allow light to pass to a light receiving area of the second layer of semiconductor material directly below the aperture and to pass to a light receiving area of the first layer of semiconductor material directly below the light receiving area of the second layer of semiconductor material.

3. The device of claim 2 wherein a depletion region of the first photodiode junction does not extend to the light receiving area of the first layer of semiconductor material when the first selected voltage is applied between the first and second electrodes, and wherein the depletion region of the first photodiode junction extends to the light receiving area of the first layer of semiconductor material when the second selected voltage is applied between the first and second electrodes.

4. The device of claim 3 wherein the first and second layers of semiconductor material are both of a same first conductivity type, the first layer of semiconductor material having a first concentration of dopant atoms, the second layer of semiconductor material having a second concentration of dopant atoms.

5. The device of claim 4 wherein the first and second contacts are metal and the first and second photodiode junctions are Schottky junctions.

6. The device of claim 4 wherein the first and second contacts are a semiconductor material having a second conductivity type different than the first conductivity type.

7. The device of claim 6 wherein the first and second layers of semiconductor material are doped N and a third layer of semiconductor material is doped P.

8. The device of claim 4 , comprising a buffer material positioned between the first and second layers of semiconductor material, wherein the buffer material inhibits light in a third wavelength band between the first and second wavelength bands from passing between the first and second layers of semiconductor material.

9. The device of claim 8 wherein the buffer material is a dielectric material.

10. The device of claim 8 wherein the buffer material is a semiconductor material having the first conductivity type and a dopant atom concentration between the first and second concentrations of dopant atoms.

11. The device of claim 1 wherein the photodiode has a substantially constant sensitivity to light in the first wavelength band when the first or the second selected voltage is applied between the first and second electrodes.

12. The device of claim 1 wherein the first electrode is positioned below the first and second layers of semiconductor material.

13. The device of claim 1 wherein the first and second layers of semiconductor material are monocrystalline, the second layer of semiconductor material being epitaxially grown from the first layer of semiconductor material.

14. The device of claim 13 wherein the first and second contact are coupled together and are formed of the same material.

Assignees

• St Microelectronics Srl

Inventors

• Mazzillo Massimo Cataldo
• SCIUTO Antonella
• Sutera Dario

Classifications

• H01L31/1013 Primary

  Electricity · mapped topic

• H01L31/108

  Electricity · mapped topic

• H10F77/241

  comprising ring electrodes · CPC title

• H10F77/122

  comprising only Group IV materials · CPC title

• H10F77/14

  Shape of semiconductor bodies; Shapes, relative sizes or dispositions of semiconductor regions within semiconductor bodies · CPC title