Method and structure for nitride based laser diode arrays on an insulating substrate

• US 6,744,800 B1
• Filed: 12/30/1998
• Issued: 06/01/2004
• Est. Priority Date: 12/30/1998
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Johnson, Noble M., Walker, Jack, Bour, David P., Kneissl, Michael A., Paoli, Thomas L.
• Primary Examiner(s): LEUNG, QUYEN PHAN
• Application Number:
  US09/223,112
• Time in Patent Office: 1,980 Days
• Field of Search: 372/50, 372/75, 372/45, 372/46, 347/238
• US Class Current: 372/50.1
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 21/2007 Bonding of semiconductor wafers to insulating substrates or to semiconducting substrates using an intermediate insulating layer H01L21/2011 takes precedence; bonding of semiconductor wafers to semiconductor wafers for junction formation H01L21/187
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 2221/68359 used as a support during manufacture of interconnect decals or build up layers
• CPC Class Codes: H01L 2221/68368 used in a transfer process involving at least two transfer steps, i.e. including an intermediate handle substrate
• CPC Class Codes: H01L 2224/83192 wherein the layer connectors are disposed only on another item or body to be connected to the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/83895 between electrically conductive surfaces, e.g. copper-copper direct bonding, surface activated bonding
• CPC Class Codes: H01L 27/153 in a repetitive configuration, e.g. LED bars
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01S 5/0217 Removal of the substrate
• 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 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence
• CPC Class Codes: H01S 5/4031 Edge-emitting structures

Abstract

A method and structure for nitride based laser diode arrays on an insulating substrate is described. Various contact layouts are used to reduce electrical and thermal crosstalk between laser diodes in the array. A channel structure is used to make a surface emitting laser diode while maintaining a simple contact structure. Buried layers are used to provide a compact and low crosstalk contact structure for the laser diode array.

Claims

1. A structure for an array of laser diodes comprising:

a first metallization layer comprising type one metal contacts;

a second metallization layer comprising at least one type two metal contact;

a plurality of active regions for generating light of a predetermined frequency disposed below said first metallization layer, each active region in said plurality of active regions electrically coupled to a corresponding type one metal contact in said first metallization layer;

first and second waveguide structures that include, respectively, first and second ones of the active regions;

each of the first and second waveguide structures further including laser mirror elements;

the first waveguide structure having a first lateral surface, the second waveguide structure having a second lateral surface disposed toward and separated from the first lateral surface;

an isolation layer of dielectric material over the first and second lateral surfaces, the dielectric material preventing optical coupling at each of the first and second lateral surfaces;

a lateral contact layer that couples at least two active regions in the plurality of active regions for generating light to the at least one type two metal contact in the second metallization layer, the at least two active regions having the same thickness for generating light at the same predetermined frequency; and

an insulating substrate supporting said plurality of active regions, said first and second waveguide structures, said isolation layer, said lateral contact layer, said first metallization layer and said second metallization layer.

2. The structure of claim 1 wherein said insulating substrate is comprised of Al₂O₃.

3. The structure of claim 1 wherein a first portion of said plurality of active regions is separated from a second portion of said plurality of active regions by a channel structure, said channel structure comprising mirrors such that light generated by said first portion and said second portion of said plurality of active regions is outcoupled by said mirrors in a direction substantially perpendicular to said metallization layer.

4. The structure of claim 1 wherein each active region in the plurality of active regions is individually addressable to allow individual switching of each active region.

5. A structure comprising:

an insulating substrate;

a laser diode array on the insulating substrate;

the laser diode structure comprising;

a type one metallization layer that includes first and second type one metal contacts;

a type two metallization layer that includes first and second type two metal contacts;

first and second active regions disposed below the type one metallization layer, the first active region being electrically coupled between the first type one and type two metal contacts, the second active region being electrically coupled between the second type one and type two metal contacts;

a lateral contact layer that couples the first and second active regions to the first and second type two metal contacts, respectively;

the first type one and type two metal contacts extending across the insulating substrate in a first alignment, the second type one and type two metal contacts extending across the insulating substrate in a second alignment different than the first alignment, the first and second alignments being at an angle that increases separation between the first type one and type two metal contacts and the second type one and type two metal contacts.

6. A structure for an array of laser diodes comprising:

a metallization layer comprising type one metal contacts;

a plurality of active regions for generating light disposed below said metallization layer, each active region electrically coupled to a corresponding contact in said metallization layer, each active region in said plurality of active regions having a common thickness, each active region in said plurality of active regions to output a common predetermined wavelength of light;

laser mirror elements for each of the active regions;

a type two contact layer wherein the type two contact layer includes a nitride based compound, the type two contact layer further including a type two metal contact disposed below said plurality of active regions, the type two metal contact electrically coupled to at least two active regions in said plurality of active regions; and

an insulating substrate proximate to and supporting said type two contact layer.

7. The structure of claim 6 wherein each of said plurality of active regions has a multi-quantum well structure.

8. A structure for an array of laser diodes comprising:

a metallization layer comprising type one metal contact;

a plurality at active regions for generating light disposed below said metallization layer, each active region electrically coupled to a corresponding contact in said metallization layer, each active region in said plurality of active regions having a common thickness, each active region in said plurality of active regions to output a common predetermined wavelength of light;

laser mirror elements for each of the active regions;

a type two contact layer wherein said type two contact layer is comprised of GaN and is an n-type layer, said type two contact layer including a type two metal contact disposed below said plurality of active regions, the type two metal contact electrically coupled to at least two active regions in said plurality of active regions; and

an insulating substrate proximate to and supporting said type two contact layer.

9. A structure for an array of laser diodes comprising:

a metallization layer comprising type one metal contacts;

a plurality of active regions for generating light disposed below said metallization layer, each active region electrically coupled to a corresponding contact in said metallization layer, each active region in said plurality of active regions having common thickness, each active region in said plurality of active regions to output a common predetermined wavelength of light;

laser mirror elements for each of the active regions;

a type two contact layer including a type two metal contact disposed below said plurality of active regions, the type two metal contact electrically coupled to at least two active regions in said plurality of active regions;

a type one layer disposed between said plurality of active regions and said type two contact layer; and

,

an insulating substrate proximate to and supporting said type two contact layer.

10. A laser array to define placement of a marking material in a laser printer, the laser array comprising:

a first metallization layer comprising type one metal contacts;

a second metallization layer comprising at least one type two metal contact;

a plurality of active regions for generating light of a predetermined frequency disposed below said first metallization layer, each active region in said plurality of active regions having a common thickness, each active region to output a corresponding beam of light having the predetermined frequency, each beam of light to define areas of a substrate to receive said marking material, each active region in said plurality of active regions electrically coupled to a corresponding type one metal contact in said first metallization layer;

first and second waveguide structures that include, respectively, first and second ones of the active regions;

each of the first and second waveguide structures further including laser mirror elements;

the first waveguide structure having a first lateral surface, the second waveguide structure having a second lateral surface disposed toward and separated from the first lateral surface;

an isolation layer of dielectric material over the first and second lateral surfaces, the dielectric material preventing optical coupling at each of the first and second lateral surfaces;

a lateral contact layer that couples at least two active regions in the plurality of active regions for generating light to the at least one type two metal contact in the second metallization layer, the at least two active regions having the same thickness for generating light at the same predetermined frequency; and

an insulating substrate supporting said plurality of active regions, said first and second waveguide structures, said isolation layer, said lateral contact layer, said first metallization layer and said second metallization layer.

11. A laser array, comprising:

an insulating substrate with a surface;

a laser array structure formed on the substrate'"'"'s surface, the laser array structure including two or more lasers;

each laser having a waveguide structure that includes an active region for generating light in response to a respective electrical signal;

each laser amplifying its generated light through stimulated emission of radiation with optical feedback to obtain coherent light, at least part of the coherent light from each laser being coupled out of the laser;

the structure further including;

a first metallization layer that includes contacts of a first type and at least one second metallization layer that includes contacts of a second type;

each laser'"'"'s active region being connected to receive its respective electrical signal through one of the contacts of the first type and one of the contacts of the second type;

each laser'"'"'s active region being between the first metallization layer and the insulating substrate;

the lasers including first and second lasers adjacent to each other, the waveguide structure of the first laser having a first lateral surface, the waveguide structure of the second laser having a second lateral surface disposed toward and separated from the first lateral surface;

an isolation layer of dielectric material over the first and second lateral surfaces, the dielectric material preventing optical coupling at each of the first and second lateral surfaces; and

a lateral contact structure through which the active regions of at least two of the lasers are electrically connected to contacts of the second type.

12. The laser array of claim 11 in which each laser includes two mirror facets perpendicular to the substrate surface and parallel to each other, the two mirror facets providing optical feedback within the laser and one of the mirror facets coupling coherent light out of the laser.

13. The laser array of claim 11 in which the active regions of all the lasers are of the same thickness for generating light at the same frequency.

14. The laser array of claim 11 in which the active region of each laser is electrically connected to a respective contact of the second type, the respective contact of the second type for each laser not being connected to the active region of any other laser.

15. The laser array of claim 14 in which the active region of each laser is further electrically connected to a respective contact of the first type, the respective contact of the first type for each laser not being connected to the active region of any other laser;

the respective contacts of the first and second types for first and second lasers extending across the insulating substrate in two different alignments;

the two different alignments being at an angle that increases separation between the first and second lasers.

16. The laser array of claim 14 in which the lateral contact structure comprises first and second lateral contact layers;

the first lateral contact layer electrically connecting the first laser'"'"'s active region to its respective contact of the second type;

the second lateral contact layer electrically connecting the second laser'"'"'s active region to its respective contact of the second type.

17. The laser array of claim 11 in which the active regions of two lasers are both electrically connected to one shared contact of the second type.

18. The laser array of claim 11 in which the lateral contact structure includes an n-type semiconductor layer, the active regions being electrically connected to contacts of the second type through the n-type semiconductor layer;

the laser array structure further including a p-type semiconductor layer between the active regions of the lasers and the first metallization layer, the active regions being electrically connected to contacts of the first type through the p-type semiconductor layer.

19. The laser array of claim 11 in which the dielectric material is silicon oxy-nitride, silicon dioxide, silicon nitride, or polyimide.