Abstract
In an embodiment an optoelectronic array includes a first structured layer with a plurality of first regions, the first structured layer including a semiconductor material of a first doping type, a second structured layer with a plurality of second regions arranged on the first structured layer, the second structured layer including a semiconductor material of a second doping type and a plurality of active regions arranged between respective first and second regions forming optoelectronic elements, wherein first regions along a row of the plurality of rows are connected by first contact bridges, wherein second regions along a column of the plurality of columns are connected by second contact bridges, wherein the first contact bridges comprise a semiconductor material of the first doping type, and wherein the second contact bridges comprise a semiconductor material of the second doping type.
Claims
1.-33. (canceled)
34. An optoelectronic array with a plurality of optoelectronic elements arranged in a plurality of rows and columns, the array comprising: a first structured layer with a plurality of first regions, the first structured layer comprising a semiconductor material of a first doping type; a second structured layer with a plurality of second regions arranged on the first structured layer, the second structured layer comprising a semiconductor material of a second doping type; and a plurality of active regions arranged between respective first and second regions forming the optoelectronic elements, wherein first regions along a row of the plurality of rows are connected by first contact bridges, wherein second regions along a column of the plurality of columns are connected by second contact bridges, wherein the first contact bridges comprise a semiconductor material of the first doping type, and wherein the second contact bridges comprise a semiconductor material of the second doping type.
35. The optoelectronic array according to claim 34, wherein the first contact bridges comprise a higher doping concentration of the first doping type than the first regions.
36. The optoelectronic array according to claim 34, wherein the second contact bridges comprise a higher doping concentration of the second doping type than the second regions.
37. The optoelectronic array according to claim 34, further comprising a plurality of first contacts, each contact coupled to a first region of an optoelectronic element of an outer row of the optoelectronic array.
38. The optoelectronic array according to claim 37, wherein each of the plurality of first contacts comprises a contact via through the second structured layer.
39. The optoelectronic array according to claim 34, further comprising a plurality of second contacts, each contact coupled to a second region of an optoelectronic element of an outer column of the optoelectronic array.
40. The optoelectronic array according to claim 39, wherein each of the plurality of second contacts comprises a contact pad arranged on the second structured layer.
41. The optoelectronic array according to claim 34, wherein each first region jackets respective second regions at least partly.
42. The optoelectronic array according to claim 34, wherein the first contact bridges and/or the second contact bridges comprise nanorods.
43. The optoelectronic array according to claim 34, further comprising an electrically insulating material arranged in trough holes between the optoelectronic elements.
44. The optoelectronic array according to claim 34, wherein the first contact bridges remain free of the semiconductor material of the second doping type.
45. The optoelectronic array according to claim 34, wherein the second contact bridges remain free of the semiconductor material of the first doping type.
46. The optoelectronic array according to claim 34, wherein the first contact bridges comprise a thickness which is smaller than a thickness of the first structured layer, and wherein the second contact bridges comprise a thickness which is smaller than a thickness of the second structured layer.
47. The optoelectronic array according to claim 34, wherein the first contact bridges comprise an at least approximately equal thickness as a thickness of the first structured layer, and wherein the second contact bridges comprise an at least approximately equal thickness as a thickness of the second structured layer.
48. The optoelectronic array according to claim 34, wherein the first contact bridges comprise a width which is smaller than a width of a first region being in contact with the respective first contact bridge.
49. The optoelectronic array according to claim 34, wherein the second contact bridges comprise a width which is smaller than a width of a second region being in contact with the respective second contact bridge.
50. The optoelectronic array according to claim 34, wherein respective first and second regions are arranged above each other at least approximately congruently.
51. The optoelectronic array according to claim 34, wherein each of the first and second regions comprises one of a rectangular, round, oval, trapezoidal, or polygonal cross section.
52. A method for manufacturing an optoelectronic array with a plurality of optoelectronic elements arranged in a plurality of rows and columns, the method comprising: providing a layer stack of a first layer and a second layer, the first layer comprising a semiconductor material of a first doping type and the second layer comprising a semiconductor material of a second doping type; etching first openings into the second layer, wherein the first openings are formed between optoelectronic elements along the columns; etching second openings into the first layer, wherein the second openings are formed between optoelectronic elements along the rows; and etching through holes through the layer stack, wherein the through holes and the second openings structure the first layer into a plurality of first regions and a plurality of first contact bridges, wherein the through holes and the first openings structure the second layer into a plurality of second regions and a plurality of second contact bridges, wherein first regions along a row of the plurality of rows are connected by the first contact bridges, wherein second regions along a column of the plurality of columns are connected by the second contact bridges, and wherein each of a first region and a respective second region with an active region arranged therebetween forms an optoelectronic element.
53. The method according to claim 52, wherein the layer stack is provided on a first carrier substrate, the first layer facing the first carrier substrate.
54. The method according to claim 52, further comprising providing at least one second contact on an edge region of the second layer.
55. The method according to claim 52, further comprising providing a release layer on the second layer.
56. The method according to claim 55, further comprising providing a second carrier substrate on the release layer.
57. The method according to claim 53, further comprising removing the first carrier substrate.
58. The method according to claim 52, further comprising providing at least one first contact on at least an edge region of the first layer.
59. The method according to claim 57, wherein etching the second openings is performed after removing the first carrier substrate.
60. The method according to claim 52, wherein etching the through holes is performed after etching the second openings.
61. The method according to claim 52, further comprising filling the through holes and/or the first and/or the second openings with an electrically insulating material.
62. The method according to claim 55, further comprising at least partially removing the release layer.
63. The method according to claim 56, further comprising a lifting off the optoelectronic array from the second carrier substrate and an optionally remaining release layer.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] In the following, embodiments of the invention will be explained in more detail with reference to the accompanying drawings.
[0048] FIGS. 1A and 1B show an optoelectronic array as well as a detailed view of the optoelectronic array according to some aspects of the invention;
[0049] FIG. 2 shows a detailed view of an embodiment of first and second contact bridges of an optoelectronic array according to some aspects of the invention;
[0050] FIG. 3 shows an isometric view of a further embodiment of an optoelectronic array according to some aspects of the invention;
[0051] FIG. 4 shows an isometric view of a further embodiment of an optoelectronic array with first and second contact elements according to some aspects of the invention;
[0052] FIGS. 5A and 5B show a side view of further embodiments of an optoelectronic array with first and second contact elements according to some aspects of the invention;
[0053] FIG. 6 shows an optoelectronic device with a plurality of optoelectronic arrays according to some aspects of the invention; and
[0054] FIG. 7A to 7J show steps of a method for manufacturing an optoelectronic array according to some aspects of the invention.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0055] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the disclosure are shown. The disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness. Like reference characters refer to like elements throughout the description. The drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the exemplary embodiments of the present disclosure.
[0056] FIG. 1A shows an optoelectronic array 1 with a plurality of optoelectronic elements 2 arranged in a plurality of rows R and columns C. The optoelectronic array 1 comprises a first structured layer 3 with a plurality of first regions 3a, and a second structured layer 4 with a plurality of second regions 4a arranged on the first structured layer 3a. The first structured layer 3 comprises a semiconductor material of a first doping type and the second structured layer 4 comprises a semiconductor material of a second doping type. Between respective first 3a and second regions 4a, each an active region 5 of a plurality of active regions 5 is arranged, each a first region 3a, a second region 4a and an active region 5 forming an optoelectronic element 2.
[0057] The optoelectronic elements 2 are electrically connected by first and second contact bridges 6, 7, in such a way that first regions 3a are connected along the rows R by first contact bridges 6 and second regions 4a are connected along the columns C by second contact bridges 7. The first regions 3a are however separated from each other along the columns C and the second regions are separated from each other along the rows R. The optoelectronic elements 2 are thus connected in form of a matrix circuit.
[0058] In a matrix circuit, individual optoelectronic elements 2 are arranged and electrically connected in columns and rows and for example all positive poles of the optoelectronic elements 2 are connected row by row by first contact bridges 6, while all negative poles are connected column by column by second contact bridges 7. As soon as a certain column and a certain row are connected to a supply voltage, current starts to flow through the optoelectronic element 2 that is located at the intersection of the connected row and column.
[0059] As shown in the detail view in FIG. 1B, the first contact bridges 6 do not intersect with the second contact bridges 7 and are also not in contact with them. In areas of the first contact bridges 6, the second structured layer 4 is removed and in areas of the second contact bridges 7 the first structured layer 3 is removed.
[0060] In addition, it is shown in FIG. 1B that the first contact bridges 6 comprise an at least approximately equal thickness t.sub.6 as the thickness t.sub.3 of the first structured layer 3/a first region 3a being in contact with the respective contact bridge, and that the second contact bridges 7 comprise an at least approximately equal thickness t.sub.y as the thickness t.sub.4 of the second structured layer 4/a second region 4a being in contact with the respective contact bridge. The width w.sub.6 of the first contact bridges 6 and the width w.sub.7 of the second contact bridges 7 is however smaller than the width w.sub.3a, w.sub.4a of a first or second region 3a, 4a being in contact with the respective contact bridge. In the shown embodiment, the first and second regions 3a, 4a each have a rectangular form/are cuboid and are arranged congruently on top of each other so that the optoelectronic elements 2 are basically cubic. However, any other form or shape of the first and second regions 3a, 4a as well as the optoelectronic elements 2 is possible too.
[0061] FIG. 2 shows a detailed view of an embodiment of first and second contact bridges 6, 7 of an optoelectronic array 1. Compared to the embodiment shown in FIGS. 1A and 1B, the first bridges 6 comprise a higher doping concentration of the first doping type and the second contact bridges 7 comprise a higher doping concentration of the second doping type. This is indicated by the dotted filling of the contact bridges. The higher doping concentration thereby serves to increase the electrical conductivity of the contact bridges, as the contact bridges act as conductive tracks between the optoelectronic elements.
[0062] FIG. 3 shows an isometric view of a further embodiment of an optoelectronic array 1. The first and second regions 3a, 4a are however not cuboid, but the second regions 4a are of the form of a cone and the first regions 3a are of the form of a hollow cone. Respective first and second regions 3a, 4a are arranged on top of each other in a way, such that a first region 3a partly jackets a second region 4a. The active region 5 is arranged between a respective first and second region and thus extends along the interface between the first and second region which corresponds basically to the lateral surface of a cone.
[0063] In the embodiment shown, only an outer column C and an outer row R of the optoelectronic array is drawn, but by the dotted lines and the ellipsis (dot-dot-dot) a continuation of the array is indicated.
[0064] The first contact bridges 6 and the second contact bridges 7 comprises besides a smaller width also a smaller thickness than the respective first/second regions being in contact with the contact bridges. The contact bridges can for example comprise nanorods which are grown between respective first/second regions forming the contact bridges.
[0065] FIG. 4 shows an isometric view of a further embodiment of an optoelectronic array 1. In addition to the optoelectronic array 1 of FIG. 1A, each first contact 8 is coupled to a first region 3a of each row R of the optoelectronic array 1 and each second contact 9 is coupled to a second region 4a of each column of the optoelectronic array 1. In particular the first contacts 8 are each coupled to an outer optoelectronic element 2 of each row of the optoelectronic array 1, and thus to the optoelectronic elements 2 of an outer column of the optoelectronic array. The second contacts 9 are each coupled to an outer optoelectronic element 2 of each column of the optoelectronic array 1, and thus to the optoelectronic elements 2 of an outer row of the optoelectronic array. Through these contacts the optoelectronic elements 2 can be controlled in form of a matrix circuit.
[0066] FIGS. 5A and 5B each show a side view of further embodiments of an optoelectronic array 1 and in particular embodiments of the first and second contact elements 8, 9. According to FIG. 5A, the first contact 8 comprises a contact via 10 through the second structured layer 4 contacting the first structured layer 3/a respective first region 3a. The contact via 10 is electrically isolated from the second structured layer 4 by use of an electrically isolating material arranged between the contact via 10 and the second structured layer 4 to avoid a short. The second contact 9 comprises a contact pad arranged on the second structured layer/a respective second region 4a. The contact pad is electrically coupled to the respective second region 4a. An electrical connection of the optoelectronic array 1 can therefore be provided from the same side of the optoelectronic array, namely the side of the second structured layer 4.
[0067] FIG. 5B in contrast shows the first contact 8 without a contact via but with a conductive track 11 extending from a top surface of an optoelectronic element 2 along a side surface of the optoelectronic element 2 onto a bottom surface of the optoelectronic element 2. With the shown contact 8 an electrical connection of the optoelectronic array 1 can again be provided from the same side of the optoelectronic array, namely the side of the second structured layer 4.
[0068] In addition, and as an exemplary alternative FIG. 5B shows that the second contact bridges 7 comprise a higher doping concentration of the second doping type. This is indicated by the dotted filling of the contact bridges. The higher doping concentration thereby serves to increase the electrical conductivity of the contact bridges, as the contact bridges act as conductive tracks between the optoelectronic elements. It is to be understood, that the first contact bridges (not shown in this viewing angle) may also comprise a higher doping concentration, but may also not.
[0069] FIG. 6 shows an optoelectronic device 100 with a plurality of optoelectronic arrays 1 arranged on a circuit board 12 in rows and columns. The optoelectronic device 100 may for example form a display. The optoelectronic arrays 1, and in particular the rows and columns of the optoelectronic arrays 1 are connected to contact pads 13 on the circuit board 12 so that they can be controlled by the same.
[0070] FIG. 7A to 7J show steps of a method for manufacturing an optoelectronic array 1 with a plurality of optoelectronic elements arranged in a plurality of rows and columns.
[0071] In a first step according to FIG. 7A, a layer stack 20 of a continuous first layer 3.sub.o, a continuous second layer 4.sub.o, and a continuous active region 5.sub.o between the first layer 3.sub.o and the second layer 4.sub.o is provided on a first carrier substrate 14, the first layer 3.sub.o facing the first carrier substrate 14. The first layer 3.sub.o comprises a semiconductor material of a first doping type, and the second layer 4.sub.o comprises a semiconductor material of a second doping type. The step of providing the layer stack 20 comprises an epitaxial growing of the layer stack on the first carrier substrate 14, wherein the first carrier substrate is for example a wafer.
[0072] In a further step according to FIG. 7B, first openings 15 are etched into the second layer 4.sub.o. The first openings 15 are thereby arranged between later separated optoelectronic elements along the rows of the manufactured optoelectronic array. The first openings 15 are in particular etched into the second layer 4.sub.o in areas, where later first contact bridges are generated in the first layer 3.sub.o. Therefore, the first openings 15 are etched into the second layer 4.sub.o with such a depth that the second layer 4.sub.o is removed completely in these areas.
[0073] FIG. 7C shows only an edge region of the layer stack, in particular the edge region corresponding to one later formed optoelectronic element. The continuation of the layer stack 20 and the respective further layers and components is indicated by the waved lines.
[0074] In the step shown, a second contact 9 is provided on an edge region of the second layer 4.sub.o. In particular the second contact 9 is provided on an edge region of the second layer 4.sub.o such that it is arranged on a later formed outer optoelectronic element of a column of the optoelectronic array. In addition, an electrically isolating/protection layer 16, for example silicon dioxide, is arranged on the second layer 4.sub.o to protect the layer stack from external influences as well as from an undesired short within the later optoelectronic array. The electrically isolating/protection layer 16 can also comprise reflective/light absorbing properties to guide light emitted from the later optoelectronic array but is an optional layer.
[0075] After this, a contact pad 17 is provided on top of the second contact 9, to contact the later optoelectronic array and to connect it to an external supply voltage. The contact pad 17 can for example comprise a metal layer and can for example form an integral part with the second contact 9.
[0076] According to FIG. 7D in a further step, a release layer 18 is provided on the electrically isolating/protection layer 16 contact pad 17. As the electrically isolating/protection layer 16 is an optional layer and as the contact pad 17 can form an integral part with the second contact 9 the release layer 18 can also be provided directly on the second layer 4.sub.o and the second contact 9. The release layer serves at least partially as a sacrificial layer which in the further processing of the optoelectronic array is at least partially again removed. On the release layer 18 a holding structure comprising a second carrier substrate 20 and an intermediate layer 19 is provided in a subsequent step. The second carrier substrate 20 serves to provide a structure with which the layer stack 20 can be held to process the side of the layer stack opposing the second carrier substrate 20.
[0077] As shown in FIG. 7E the step of providing the second carrier substrate 20 is followed by a step of turning the layer stack by 180. The first carrier substrate 14 is then removed and a first contact 8 in form of a transparent contact layer of for example indium tin oxide is provided on the layer stack 2.sub.o, and in particular on the first layer 3.sub.o.
[0078] After this, as shown in FIG. 7F, second openings 21 are etched into the first layer 3.sub.o and the transparent contact layer. The second openings 21 are thereby arranged between later separated optoelectronic elements along the columns of the manufactured optoelectronic array. The second openings 15 are in particular etched into the first layer 3.sub.o in areas, where later second contact bridges are generated in the second layer 4.sub.o. Therefore, the second openings 21 are etched into the first layer 3.sub.o with such a depth that the first layer 3.sub.o is removed completely in these areas.
[0079] In a further step according to FIG. 7G, through holes 22 are etched through the layer stack 20 until the release layer 18. The through holes 22 are indicated by the hatching to show that the hatched area is to be removed. Depending on the desired form of the optoelectronic elements and the contact bridges with regard to shape size and size ratio to each other the through holes can however comprise a different size and or shape. The through holes 22 and the second openings 21 structure the first layer into a plurality of first regions 3a and a plurality of first contact bridges 7, while the through holes 8 and the first openings 15 structure the second layer into a plurality of second regions 4a and a plurality of second contact bridges 7. With the step of etching the first and second openings 15, 21 in combination with the step of etching the trough holes 22 through the layer stack 20, the plurality of optoelectronic elements 2, as well as the first and second contact bridges 6,7 are generated.
[0080] FIG. 7H shows a further step according to which the through holes 22 and the first and the second openings 15, 21 are filled with an electrically insulating material 23, such as for example a ceramic or a plastic material. The electrically insulating material can for example serve as an electrical isolation between the optoelectronic elements 2 and between first and second contact bridges 6,7, can for example serve as a mechanical stabilizer of the optoelectronic array, and can for example serve as a reflective or light absorbing medium between the optoelectronic elements 2, in particular surrounding the optoelectronic elements 2.
[0081] In a subsequent step, as shown in FIG. 7I, the release layer 18 is partially removed. In particular, the release layer 18 is removed such that only a pillar of the release layer 18 remains between the second structured layer 3 and the intermediate layer 19. By this, the optoelectronic array 1 can easily be removed from the holding structure for example.
[0082] FIG. 7J shows a last step of a lift off process of the optoelectronic array 1 from the holding structure and the remaining release layer pillar. The release layer pillar can thereby hold the optoelectronic array 1 in place ad act as a breaking point from which the optoelectronic array 1 can be torn off from when picked up by a Stamp 24.
