SEMICONDUCTING PIXEL, MATRIX OF SUCH PIXELS, SEMICONDUCTING STRUCTURE FOR THE PRODUCTION OF SUCH PIXELS AND THEIR METHODS OF FABRICATION

• US 20170213868A1
• Filed: 03/27/2015
• Published: 07/27/2017
• Est. Priority Date: 04/01/2014
• Status: Active Grant

• Current Assignee: Centre National De La Recherche Scientifique
• Original Assignee: Centre National De La Recherche Scientifique
• Inventors: DUBOZ, Jean-Yves, DAMILANO, Benjamin
• Granted Patent: US 10,103,195 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 27/153 in a repetitive configuration, e.g. LED bars
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

A pixel comprises three adjacent sub-pixels, formed by respective stacks of semi-conducting layers wherein: each sub-pixel comprises a first active layer, adapted for emitting a light at a first wavelength when an electric current passes through it; another sub-pixel comprises a second active layer, adapted for emitting a light at a second wavelength greater than the first wavelength; another sub-pixel comprises a third active layer, adapted for emitting a light at a third wavelength greater than the first wavelength and different from the second wavelength; at least one from among the second and third active layers being adapted for emitting light when it is excited by the light at the first wavelength emitted by the first active layer of the same sub-pixel. Semi-conducting structure and methods for the fabrication of such a pixel are provided.

Claims

1. A pixel comprising at least three sub-pixels disposed one alongside the other, each said sub-pixel comprising a respective stack of semi-conducting layers, wherein:

each said sub-pixel comprises a first active layer, adapted for emitting a light at a first wavelength when an electric current passes through it;

at least one said sub-pixel, termed the first sub-pixel, also comprises a first and a second electrode arranged on either side of said first active layer so as to allow an electric current to pass through it;

another of said sub-pixels, termed the second sub-pixel, also comprises a second active layer, adapted for emitting a light at a second wavelength greater than said first wavelength;

another of said sub-pixels, termed the third sub-pixel, also comprises a third active layer, adapted for emitting a light at a third wavelength greater than said first wavelength and different from said second wavelength;

at least one from among said second and third active layers being adapted for emitting said light when it is excited by the light at the first wavelength emitted by said first active layer of the same sub-pixel

wherein;

said first active layer is at least partially transparent to said second wavelength;

said second active layer of said second sub-pixel is arranged on a first side of said first active layer and adapted for emitting said light at said second wavelength when it is traversed by an electric current, said second sub-pixel also comprising a third and a fourth electrode arranged on either side of said second active layer so as to allow an electric current to pass through it without passing through said first active layer; and

said third active layer of said third sub-pixel is arranged on a second side of said first active layer, opposite to said first side, and adapted for emitting said light at said third wavelength when it is excited by the light at the first wavelength emitted by said first active layer of said third sub-pixel, said third sub-pixel also comprising a fifth and a sixth electrode arranged on either side of said first active layer so as to allow an electric current to pass through it.

2. The pixel as claimed in claim 1, wherein said first wavelength belongs to the blue part of the visible spectrum, said second wavelength to its red part and said third wavelength to its green part.

3. The pixel as claimed in claim 1, wherein said first wavelength belongs to the blue part of the visible spectrum, said second wavelength to its green part and said third wavelength to its red part.

4. The pixel as claimed in claim 1, exhibiting a monolithic structure.

5. The pixel as claimed in claim 3, exhibiting a monolithic structure with the exception of said third active layer, which is added.

6. The pixel as claimed in claim 1, wherein said active layers are produced based on (Al,Ga,In)N.

7. The pixel as claimed in claim 1, wherein said first active layers of said sub-pixels are coplanar, of the same composition and of the same structure.

8. A matrix of pixels comprising a plurality of pixels according to claim 1, hybridized on a host substrate carrying a control circuit for said sub-pixels, said first and third active layers being respectively the active layer closest to and furthest from said host substrate.

12. A method for fabricating a pixel as claimed in claim 5,

comprising the following steps:

a′

) procuring a semi-conducting structure comprising;

a first subset of semi-conducting layers forming a light-emitting diode comprising an electroluminescent layer, termed the first active layer, adapted for emitting a light at a wavelength termed the first wavelength; and

a second subset of semi-conducting layers forming a light-emitting diode comprising an electroluminescent layer, termed the second active layer, adapted for emitting a light at a wavelength termed the second wavelength, greater than said first wavelength;

b) etching said structure to define a first, a second and a third pads intended to form respective sub-pixels, by means of an etching extending through said first and second active layers;

c) etching said first pad and said third pad, but not said second pad, so as to remove said second active layer therefrom;

d) producing a pair of electrical contacts situated on either side of said second active layer of said second, and two pairs of electrical contacts situated on either side of said first active layer of said first and third pads;

e) removing said substrate; and

f′

) either adding, in place of said substrate, a photoluminescent layer termed the third active layer adapted for emitting a light at a third wavelength when it is excited by a light at said first wavelength, and then removing by etching said third active layer in correspondence with said first and second pads;

or adding said third active layer in correspondence with said third pad and with the exclusion of said first and second pads.

9. A semi-conducting structure comprising a stack of semi-conducting epitaxial layers deposited on a substrate, said stack comprising, starting from said substrate:

a first subset of semi-conducting layers comprising at least one photoluminescent layer, termed the third active layer, adapted for emitting a light at a wavelength termed the third wavelength, said layers exhibiting a doping of one and the same type;

a second subset of semi-conducting layers forming a light-emitting diode comprising an electroluminescent layer, termed the first active layer, adapted for emitting a light at a wavelength termed the first wavelength; and

a third subset of semi-conducting layers forming a light-emitting diode comprising an electroluminescent layer, termed the second active layer, adapted for emitting a light at a wavelength termed the second wavelength;

said first, second and third wavelengths being mutually different and said first wavelength being less than said second and third wavelengths.

10. The semi-conducting structure as claimed in claim 9, wherein said first subset of semi-conducting layers exhibits a doping of type n and wherein a tunnel junction is interposed between said second subset and said third subset of semi-conducting layers.

11. A method for fabricating a pixel comprising at least three sub-pixels disposed one alongside the other, each said sub-pixel comprising a respective stack of semi-conducting layers, wherein:

each said sub-pixel comprises a first active layer, adapted for emitting a light at a first wavelength when an electric current passes through it;

at least one said sub-pixel, termed the first sub-pixel, also comprises a first and a second electrode arranged on either side of said first active layer so as to allow an electric current to pass through it;

another of said sub-pixels, termed the second sub-pixel, also comprises a second active layer, adapted for emitting a light at a second wavelength greater than said first wavelength;

another of said sub-pixels, termed the third sub-pixel, also comprises a third active layer, adapted for emitting a light at a third wavelength greater than said first wavelength and different from said second wavelength;

at least one from among said second and third active layers being adapted for emitting said light when it is excited by the light at the first wavelength emitted by said first active layer of the same sub-pixel

wherein;

said first active layer is at least partially transparent to said second wavelength;

said second active layer of said second sub-pixel is arranged on a first side of said first active layer and adapted for emitting said light at said second wavelength when it is traversed by an electric current, said second sub-pixel also comprising a third and a fourth electrode arranged on either side of said second active layer so as to allow an electric current to pass through it without passing through said first active layer; and

said third active layer of said third sub-pixel is arranged on a second side of said first active layer, opposite to said first side, and adapted for emitting said light at said third wavelength when it is excited by the light at the first wavelength emitted by said first active layer of said third sub-pixel, said third sub-pixel also comprising a fifth and a sixth electrode arranged on either side of said first active layer so as to allow an electric current to pass through it, the method comprising the following steps;

a) procuring a semi-conducting structure as claimed in claim 9;

b) etching said structure to define a first, a second and a third pads intended to form respective sub-pixels, by means of an etching extending at least through said first and second active layers;

c) etching said first pad and said third pad, but not said second pad, so as to remove said second active layer therefrom;

d) producing a pair of electrical contacts situated on either side of said second active layer of said third, and two pairs of electrical contacts situated on either side of said first active layer of said first and second pads;

e) removing said substrate; and

f) etching the structure so as to remove said third active layer in correspondence with said first and second pads, but not with said third pad.