Quantum Photonic Imagers and Methods of Fabrication Thereof

• US 20090278998A1
• Filed: 06/17/2009
• Published: 11/12/2009
• Est. Priority Date: 09/27/2007
• Status: Active Grant

• Current Assignee: Ostendo Technologies Inc.
• Original Assignee: Ostendo Technologies Inc.
• Inventors: El-Ghoroury, Hussein S., McNeill, Dale A., DenBoer, Huibert, Lanzone, Andrew J., Brown, Robert G.W.
• Granted Patent: US 7,829,902 B2
• Time in Patent Office: Days
• US Class Current: 348/744
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: H01S 5/02345 Wire-bonding
• CPC Class Codes: H01S 5/18 Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities
• CPC Class Codes: H01S 5/2009 by using electron barrier layers
• CPC Class Codes: H01S 5/3063 using Mg
• CPC Class Codes: H01S 5/34326 with a well layer based on InGa(Al)P, e.g. red laser
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser
• CPC Class Codes: H01S 5/4043 with vertically stacked active layers
• CPC Class Codes: H01S 5/4093 Red, green and blue [RGB] generated directly by laser action or by a combination of laser action with nonlinear frequency conversion
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

Emissive quantum photonic imagers comprised of a spatial array of digitally addressable multicolor pixels. Each pixel is a vertical stack of multiple semiconductor laser diodes, each of which can generate laser light of a different color. Within each multicolor pixel, the light generated from the stack of diodes is emitted perpendicular to the plane of the imager device via a plurality of vertical waveguides that are coupled to the optical confinement regions of each of the multiple laser diodes comprising the imager device. Each of the laser diodes comprising a single pixel is individually addressable, enabling each pixel to simultaneously emit any combination of the colors associated with the laser diodes at any required on/off duty cycle for each color. Each individual multicolor pixel can simultaneously emit the required colors and brightness values by controlling the on/off duty cycles of their respective laser diodes.

Claims

1-23. -23. (canceled)

24. A digital semiconductor structure for bonding to a two-dimensional multicolor light emitting pixel array comprising:

multiple two dimensional arrays of pixel logic cells;

a digital control logic region positioned at the periphery of the array of pixels logic cells;

a plurality of device contact pads positioned at the periphery of the digital control logic region; and

a plurality of metal layers configured to;

interconnect the array of pixels logic cells with the digital control logic region;

connect the digital control logic region with the plurality of the device contact pads; and

interconnect the array of pixel logic cells with a two-dimensional multicolor light emitting pixel array.

25. The structure of claim 24 wherein the top metal layer is comprised of an array of pixel contact pads patterned to match a two-dimensional multicolor light emitting pixel array to be bonded thereto.

26. The structure of claim 25 wherein one metal layer comprises a plurality of separate power and ground rails for distributing power and ground to:

the digital control logic region;

the array of pixels logic cells; and

a two-dimensional multicolor light emitting pixel array to be bonded to the pixel contact pads.

27. The structure of claim 26 wherein one metal layer comprises a plurality metal traces for distributing data, update and clear signals to the pixels logic cells.

28. The structure of claim 27 wherein one metal layer comprises a plurality of separate metal traces for distributing the load and enable signals to the pixels logic cells.

29. The structure of claim 28 wherein each two dimensional array of pixel logic cells comprise a plurality of logic circuits that:

gate power to respective pixel contact pads in response to an enable signal generated by the digital control logic region;

and latch the next on-off states of the respective pixel contact pads for one color of a two-dimensional multicolor light emitting pixel array to be bonded thereto in response to load signals generated by the digital control logic region.

30. The structure of claim 29 wherein the plurality of logic circuits each:

generate the enable and load signals for each respective pixel logic cell in response to a serial bit stream input provided by a companion device that defines the on-off states of the respective pixel contact pads of a two-dimensional multicolor light emitting pixel array to be bonded thereto within a duration of an input clock period, the serial bit stream and clock inputs being routed to the digital control logic region via the plurality of device contact pads.

31. A projector comprising:

an emissive multicolor digital image forming device in the form of a two dimensional array of multicolor laser emitting pixels; and

a projection lens group coupled to the emissive aperture of the multicolor imager device to magnify the image size formed by the emissive multicolor digital image forming device.

32. The projector of claim 31 further comprising a companion device and a printed circuit board upon which the emissive multicolor digital image forming device and its companion device are mounted, the projection lens group being mounted in position to effect the optical coupling of the emissive aperture of the emissive multicolor digital image forming device.

33. The projector of claim 32 configured to accept digital image or video input and generating multicolor optical images or video representations of the digital image or video input.

34. The projector of claim 33 configured to be used in front projection or rear projection display systems to display multicolor images or video.

35. The projector of claim 33 configured to be used in mobile platforms to display multicolor images or video.

36. The projector of claim 33 configured to be used in near-eye display systems to display single-color or multicolor images or video.

37. The projector of claim 31 further comprising a companion device, and wherein the companion device is electrically coupled to receive image source data and convert the image source data into the on-off duty cycle values of laser diodes comprising each of the pixels of the emissive multicolor image forming device, the companion device including

a color-space conversion block;

a uniformity correction block, including a weighting factor look-up table;

a pulse-width modulation conversion block; and

a synchronization and control block.

38. The projector of claim 37 wherein the color-space conversion block is configured to receive source image data and convert the data from a source image gamut into the emissive multicolor image forming device native gamut, and to map the converted data into on-off duty cycle values required for each of the laser diodes of the emissive multicolor image forming device.

39. The projector of claim 37 wherein the uniformity correction block is configured to receive the pixels'"'"' laser diode on-off duty cycle values and apply weighting factors of the uniformity block look-up table to provide color and brightness uniformity in a projected image.

40. The projector of claim 39 wherein the weighting factors of the uniformity block look-up table are unique to the specific emissive multicolor digital image forming device in the projector as determined by testing after fabrication of the emissive multicolor digital image forming device.

41. The projector of claim 37 wherein the synchronization and control block is configured to receive a source image frame synchronization signal and convert the source image frame synchronization signal into pixel pulse-width modulation clock signals.

42. The projector of claim 37 wherein the pulse-width-modulation block is configured to receive uniformity corrected on-off duty cycle values of each of the pixels'"'"' laser diodes and convert the uniformity corrected on-off duty cycle values into a serial bit stream that represents the on-off state of each of the pixels'"'"' laser diodes within the duration of the pulse-width-modulation clock signal generated by the synchronization and control block.

43. The projector of claim 37 wherein the projector is configured to operate in a Direct-Color Synthesize mode wherein source image pixels'"'"' color and brightness values are directly synthesized for each individual pixel in the source image using color primaries of a native gamut of the emissive multicolor image forming device.

44. The projector of claim 37 wherein the projector is configured to operate in a Sequential-Color Synthesize mode wherein:

color primaries of a source image color gamut are first synthesized using color primaries of a native gamut of the emissive multicolor image forming device; and

the source image pixels'"'"' color and brightness are then sequentially synthesized using the synthesized color primaries of the source image color gamut.

45. The projector of claim 37 wherein the projector is configured for use in wide gamut applications requiring realistic image color rendition such as simulator displays and gamming displays.

46. The method of making a two dimensional array of multicolor laser emitting pixels wherein each multicolor laser emitting pixel comprises a plurality of laser diode semiconductor structures, each for emitting a different color, stacked vertically with a grid of vertical sidewalls electrically and optically separating each multicolor pixel from adjacent multicolor pixels within the array of multicolor pixels, and a plurality of vertical waveguides optically coupled to the laser diode semiconductor structures to vertically emit laser light generated by the laser diode semiconductor structures from a first surface of the stack of laser diode semiconductor structures;

the method comprising;

a) forming laser diode semiconductor structures of different colors, each having multiple semiconductor layers of one or more of the following semiconductors alloy materials;

Al_xIn_1-xP, (Al_xGa_1-x)_yIn_1-yP, Ga_xIn_1-xP, Al_xGa_1-xN, Al_xGa_1-xN/GaN, In_xGa_1-xN, GaN, each formed on a separate wafer over a thick substrate layer of either GaAs, GaN or InGaN, each including an n-type etch-stop layer and a p-type contact layer of the same respective semiconductor substrate layer material type, each comprising n-type and p-type waveguide layers and cladding layers that define their respective optical confinement regions, each having at least one quantum well surrounded by two barrier layers that define their respective active regions, and each comprising an electron blocker layer embedded either within their respective p-type waveguide layers or between their respective p-type waveguide and cladding layers;

b) depositing a SiO₂ layer upon a Si-substrate wafer;

c) depositing an n-contact metal layer over the SiO₂ layer;

d) wafer-level bonding of the p-type contact layer of a laser diode semiconductor structure wafer of one color to the deposited n-contact metal layer and etching its GaAs, GaN or InGaN thick substrate down to its n-type etch-stop layer;

e) etching a grid of trenches with vertical sidewalls down to the n-contact metal layer and backfilling the etched trenches with SiO₂;

f) etching the trenches for vertical interconnect metal vias and backfilling etched trenches with metal;

g) depositing a p-contact metal layer and etching the sidewall trenches; and

h) depositing another SiO₂ layer;

i) repeating b) through h) for each additional color of laser diode semiconductor structure to be incorporated within the two dimensional array of multicolor laser emitting pixels;

j) depositing and etching a metal layer to form contact pads and refilling etched gaps with SiO₂;

k) etching openings for the vertical waveguides though the Si-substrate side;

l) depositing thin cladding layers on the interior walls of openings; and

m) either backfilling the interior of the openings remaining internal to the thin cladding layers with a dielectric material of leaving then air filled.

47. A method of making emissive multicolor digital image forming devices comprising:

a) forming a wafer of two dimensional arrays of multicolor laser emitting pixels whereby each multicolor laser emitting pixel comprises a plurality of laser diode semiconductor structures, each for emitting a different color, stacked vertically with a grid of vertical sidewalls electrically and optically separating each multicolor pixel from adjacent multicolor pixels within the array of multicolor pixels, a plurality of vertical waveguides optically coupled to the laser diode semiconductor structures to vertically emit laser light generated by the laser diode semiconductor structures from a first surface of the stack of laser diode semiconductor structures, and a plurality of contact pads providing electrical contact to each laser diode semiconductor structure;

b) forming a wafer of digital semiconductor structures, each having a plurality of digital semiconductor circuits in the respective digital semiconductor structure, each electrically coupled to receive control signals from the periphery of the digital semiconductor structure and electrically coupled to contact pads to separately control on/off states of each of the multicolor laser diode semiconductor structures that may be connected thereto;

c) wafer-level bonding the wafer of two dimensional arrays of multicolor laser emitting pixels and the wafer of digital semiconductor structures contact pad side to contact pad side;

d) etching through the photonic semiconductor structure of between pixel regions to expose the device contact pads; and

e) cutting the multi wafer into dies to form multiple emissive multicolor digital image forming devices.