Optoelectronic Integrated Circuit

• US 20150214425A1
• Filed: 03/24/2014
• Published: 07/30/2015
• Est. Priority Date: 01/29/2014
• Status: Active Grant

• Current Assignee: OPEL Solar, Inc. (POET Technologies Inc.), University of Connecticut (State of Connecticut)
• Original Assignee: OPEL Solar, Inc. (POET Technologies Inc.), University of Connecticut (State of Connecticut)
• Inventors: Taylor, Geoff W.
• Granted Patent: US 9,625,647 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02B 6/131 by using epitaxial growth epitaxial growth for semiconductors H01L21/02365
• CPC Class Codes: G02B 6/1347 using ion implantation ion implantation in glass C03C23/0055; ion implantation in general C23C
• CPC Class Codes: G02B 6/29338 Loop resonators
• CPC Class Codes: H01L 21/8252 the substrate being a semiconductor, using III-V technology H01L21/8258 takes precedence
• CPC Class Codes: H01L 27/0605 integrated circuits made of compound material, e.g. AIIIBV
• CPC Class Codes: H01L 27/085 including field-effect components only
• CPC Class Codes: H01L 27/1443 with at least one potential jump or surface barrier
• CPC Class Codes: H01L 29/083 Anode or cathode regions of thyristors or gated bipolar-mode devices
• CPC Class Codes: H01L 29/1066 Gate region of field-effect devices with PN junction gate
• CPC Class Codes: H01L 29/15 Structures with periodic or quasi periodic potential variation, e.g. multiple quantum wells, superlattices such structures applied for the control of light G02F1/017, applied in semiconductor lasers H01S5/34
• CPC Class Codes: H01L 29/36 characterised by the concentration or distribution of impurities in the bulk material within semiconductor regions H01L29/06
• CPC Class Codes: H01L 29/66401 with an active layer made of a group 13/15 material
• CPC Class Codes: H01L 29/74 Thyristor-type devices, e.g. having four-zone regenerative action two-terminal thyristors H01L29/87
• CPC Class Codes: H01L 29/7783 using III-V semiconductor material
• CPC Class Codes: H01L 31/02327 the optical elements being integrated or being directly associated to the device, e.g. back reflectors optical coatings H01L31/0216
• CPC Class Codes: H01L 31/03046 including ternary or quaternary compounds, e.g. GaAlAs, InGaAs, InGaAsP
• CPC Class Codes: H01L 31/035209 comprising a quantum structures
• CPC Class Codes: H01L 31/035236 Superlattices; Multiple quantum well structures
• CPC Class Codes: H01L 31/1105 the device being a bipolar phototransistor
• CPC Class Codes: H01L 31/1113 the device being a photothyristor
• CPC Class Codes: H01L 31/1129 : the device being a field-effect phototransistor
• CPC Class Codes: H01L 31/1844 : comprising ternary or quaternary compounds, e.g. Ga Al As, In Ga As P
• CPC Class Codes: H01L 33/06 : within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/105 : with a resonant cavity structure
• CPC Class Codes: H01S 5/0225 : Out-coupling of light
• CPC Class Codes: H01S 5/0421 : characterised by the semiconducting contacting layers electrodes H01S5/0425
• CPC Class Codes: H01S 5/0424 : lateral current injection
• CPC Class Codes: H01S 5/0425 : Electrodes, e.g. characterised by the structure
• CPC Class Codes: H01S 5/04257 : having positive and negative electrodes on the same side of the substrate
• CPC Class Codes: H01S 5/06203 : Transistor-type lasers H01S5/0608 takes precedence
• CPC Class Codes: H01S 5/06226 : Modulation at ultra-high frequencies
• CPC Class Codes: H01S 5/0625 : in multi-section lasers
• CPC Class Codes: H01S 5/1028 : Coupling to elements in the cavity, e.g. coupling to waveguides adjacent the active region, e.g. forward coupled [DFC] structures
• CPC Class Codes: H01S 5/1032 : Coupling to elements comprising an optical axis that is not aligned with the optical axis of the active region
• CPC Class Codes: H01S 5/1042 : Optical microcavities, e.g. cavity dimensions comparable to the wavelength
• CPC Class Codes: H01S 5/1071 : Ring-lasers
• CPC Class Codes: H01S 5/1075 : Disk lasers with special modes, e.g. whispering gallery lasers
• CPC Class Codes: H01S 5/125 : Distributed Bragg reflector [DBR] lasers
• CPC Class Codes: H01S 5/183 : having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
• CPC Class Codes: H01S 5/187 : using Bragg reflection
• CPC Class Codes: H01S 5/2027 : Reflecting region or layer, parallel to the active layer, e.g. to modify propagation of the mode in the laser or to influence transverse modes
• CPC Class Codes: H01S 5/2063 : obtained by particle bombardment
• CPC Class Codes: H01S 5/2086 : lateral etch control, e.g. mask induced
• CPC Class Codes: H01S 5/222 : having a refractive index lower than that of the cladding layers or outer guiding layers
• CPC Class Codes: H01S 5/3054 : p-doping
• CPC Class Codes: H01S 5/309 : doping of barrier layers that confine charge carriers in the laser structure, e.g. the barriers in a quantum well structure barriers in quantum wells per se H01S5/3407
• CPC Class Codes: H01S 5/34313 : with a well layer having only As as V-compound, e.g. AlGaAs, InGaAs

Abstract

A semiconductor device employs an epitaxial layer arrangement including a first ohmic contact layer and first modulation doped quantum well structure disposed above the first ohmic contact layer. The first ohmic contact layer has a first doping type, and the first modulation doped quantum well structure has a modulation doped layer of a second doping type. At least one isolation ion implant region is provided that extends through the first ohmic contact layer. The at least one isolation ion implant region can include oxygen ions. The at least one isolation ion implant region can define a region that is substantially free of charge carriers in order to reduce a characteristic capacitance of the device. A variety of high performance transistor devices (e.g., HFET and BICFETs) and optoelectronic devices can employ this device structure. Other aspects of wavelength-tunable microresonantors and related semiconductor fabrication methodologies are also described and claimed.

Claims

1. A semiconductor device comprising:

an epitaxial layer arrangement including a first ohmic contact layer and first modulation doped quantum well structure disposed above the first ohmic contact layer, wherein the first ohmic contact layer has a first doping type and the first modulation doped quantum well structure has a modulation doped layer of a second doping type; and

at least one ion first-type implant region that extends above the first ohmic contact layer.

2. A semiconductor device according to claim 1, wherein:

the at least first-type one ion implant region comprises oxygen ions.

3. A semiconductor device according to claim 1, wherein:

the at least one first-type ion implant region is substantially free of charge carriers in order to reduce a characteristic capacitance of the device.

4. A semiconductor device according to claim 1, wherein:

the epitaxial layer arrangement further comprises at least one spacer layer disposed above the first modulation doped quantum well structure;

the semiconductor device further includes a mesa formed in the at least one spacer layer, at least one second-type ion implant region disposed below the mesa in contact with the first modulation doped quantum well structure, and at least one electrode terminal formed on the mesa in contact with the at least one second-type ion implant region; and

the at least one first-type ion implant region is disposed below the mesa and below the at least one second-type ion implant region.

5. A semiconductor device according to claim 1, wherein:

the first modulation doped quantum well structure defines a QW channel of an HFET device, wherein the QW channel extends between opposed second-type ion implant regions that are in contact with corresponding source and drain terminal electrodes of the HFET device, and a gate terminal electrode of the HFET device is in contact with the first ohmic contact layer.

6. A semiconductor device according to claim 1, wherein:

the first modulation doped quantum well structure defines a QW channel of a BICFET device, wherein the QW channel is in contact with a base terminal electrode of the BICFET device, and an emitter terminal electrode of the BICFET device is in contact with the first ohmic contact layer.

7. A semiconductor device according to claim 1, wherein:

the at least one first-type ion implant region provides for lateral confinement of light within a resonant cavity defined by the epitaxial layer arrangement.

8. A semiconductor device according to claim 1, wherein:

the first modulation doped quantum well structure, the first ohmic contact layer and the at least one first-type ion implant region are all part of an optical resonator formed in the epitaxial layer arrangement, wherein the optical resonator is adapted to process light at at least one predetermined wavelength.

9. A semiconductor device according to claim 8, wherein:

the optical resonator includes a resonant cavity supporting propagation of an optical signal therein, wherein the at least one first-type ion implant region is disposed adjacent the resonant cavity.

10. A semiconductor device according to claim 9, further comprising:

a first terminal electrode in electrical contact with the first modulation doped quantum well structure; and

a second terminal electrode in electrical contact with the first ohmic contact layer.

11. A semiconductor device according to claim 10, wherein:

the first and second terminal electrodes are configured as terminals of a diode laser whereby injected electrical current flows between the first and second terminal electrodes and causes light generation and propagation within the resonant cavity.

12. A semiconductor device according to claim 10, wherein:

the first and second terminal electrodes are configured as terminals of a diode optical detector that carry electrical current caused by absorption of light propagating within the resonant cavity.

13. A semiconductor device according to claim 9, wherein:

the epitaxial layer arrangement further comprises at least one spacer layer disposed above the first modulation doped quantum well structure, a second modulation doped quantum well structure disposed above the at least one spacer layer, and a second ohmic contact layer disposed above the second modulation doped quantum well structure, wherein the second modulation doped quantum well structure has a modulation doped layer of the first doping type and the second ohmic contact layer has the second doping type; and

the semiconductor device further includes a top terminal electrode in electrical contact with the second ohmic contact layer, a first injector terminal electrode in electrical contact with the second modulation doped quantum well structure, a second injector terminal electrode in electrical contact with the first modulation doped quantum well structure, and a bottom terminal electrode in electrical contact with the first ohmic contact layer.

14. A semiconductor device according to claim 13, wherein:

the top terminal electrode, the first injector terminal electrode, the second injector terminal electrode, and the bottom terminal electrode are configured as terminals of a switching thyristor laser having an ON state whereby current flows between the top terminal electrode and bottom terminal electrode to cause light generation and propagation within the resonant cavity.

15. A semiconductor device according to claim 13, wherein:

the top terminal electrode, the first injector terminal electrode, the second injector terminal electrode, and the bottom terminal electrode are configured as terminals of a switching thyristor optical detector having an ON state whereby current flows between the top terminal electrode and bottom terminal electrode, wherein the ON state is caused by absorption of light propagation in the resonant cavity.

16. A semiconductor device according to claim 13, wherein:

the optical resonator includes a first vertical resonant cavity surrounded by an annular second resonant cavity formed in the epitaxial layer arrangement, wherein the at least one first-type ion implant region is disposed adjacent the second resonant cavity;

the semiconductor device further includes a coupling waveguide structure spaced from the second resonant cavity of optical resonator to provide for evanescent-wave optical coupling therebetween; and

the optical resonator and the coupling waveguide structure are configured to perform predetermined optical mode transformation operations selected from the group consisting of vertical propagation to in-plane propagation, in-plane propagation to vertical propagation, wavelength conversion, and combinations thereof.

17. A semiconductor device according to claim 9, wherein:

the resonant cavity has a disk-like shape and the optical signal comprises a whispering gallery optical signal, or

the resonant cavity has an annular-shape and the optical signal comprises a circulating optical signal.

18. A semiconductor device according to claim 9, wherein:

the at least one first-type ion implant region is disposed in a central region of the resonant cavity.

19. A semiconductor device according to claim 9, wherein:

the optical resonator includes a resonant cavity defined by a rib waveguide, wherein the at least one first-type ion implant region is disposed on at least one side of the rib waveguide.

20. A semiconductor device according to claim 19, wherein:

the at least one first-type ion implant regions includes two first-type ion implant regions disposed on opposed sides of the rib waveguide.

21. A semiconductor device according to claim 19, wherein:

the rib waveguide has a plurality of straight sections that are optically coupled together by bend sections.

22. A semiconductor device according to claim 9, further comprising:

a coupling waveguide structure spaced from the resonant cavity of optical resonator to provide for evanescent-wave optical coupling therebetween, wherein the resonant cavity of the optical resonator and coupling waveguide structure are defined by sidewalls of the epitaxial layer arrangement.

23. A semiconductor device according to claim 22, wherein:

the epitaxial layer arrangement is disposed above a bottom distributed Bragg reflector (DBR) mirror, wherein the sidewalls that define the resonant cavity of the optical resonator and the coupling waveguide structure extend downward to the bottom DBR mirror.

24. A semiconductor device according to claim 1, further comprising:

a plurality of DBR mirror layers formed below first ohmic contact layer of the epitaxial layer arrangement.

25. A semiconductor device according to claim 24, further comprising:

a plurality of dielectric mirror layers formed above the epitaxial layer arrangement.

26. A semiconductor device according to claim 1, wherein:

said epitaxial layer arrangement includes an N+ type doped layer for the first ohmic contact layer, a first plurality of layers that define a p-type modulation doped quantum well structure for the first modulation doped quantum well structure, a second plurality of layers that define an n-type modulation doped quantum well structure for the second n-type modulation doped structure, and at least one P+ type doped layer for the second ohmic contact layer.

27. A semiconductor device comprising:

an optical resonator including a first vertical resonant cavity surrounded by an annular second resonant cavity formed in an epitaxial layer arrangement; and

a coupling waveguide structure spaced from the second resonant cavity of optical resonator to provide for evanescent-wave optical coupling therebetween.

28. A semiconductor device according to claim 27, wherein:

the second resonant cavity of the optical resonator and the coupling waveguide structure are defined by sidewalls of the epitaxial layer arrangement.

29. A semiconductor device according to claim 27, wherein:

the coupling waveguide structure and the optical resonator are configured to perform predetermined mode transformation operations selected from the group consisting of vertical propagation to in-plane propagation, in-plane propagation to vertical propagation, wavelength conversion, and combinations thereof.

30. A semiconductor device according to claim 27, wherein:

the epitaxial layer arrangement includes a first ohmic contact layer, a first modulation doped quantum well structure disposed above the first ohmic contact layer, at least one spacer layer disposed above the first modulation doped quantum well structure, a second modulation doped quantum well structure disposed above the spacer layer, and a second ohmic contact layer disposed above the second modulation doped quantum well structure;

wherein the first ohmic contact layer has a first doping type, the first modulation doped quantum well structure has a modulation doped layer of a second doping type, the second modulation doped quantum well structure has a modulation doped layer of the first doping type, and the second ohmic contact layer has the second doping type.

31. A semiconductor device according to claim 30, wherein the resonator further comprises:

a top terminal electrode in electrical contact with the second ohmic contact layer;

at least one of a first injector terminal electrode and a second injector terminal, wherein the first injector terminal is in electrical contact with the second modulation doped quantum well structure, and the second injector terminal electrode in electrical contact with the first modulation doped quantum well structure; and

a bottom terminal electrode in electrical contact with the first ohmic contact layer.

32. A semiconductor device according to claim 31, wherein:

the electrodes of the device are configured as terminals of a switching thyristor laser having an ON state, whereby current flows between the top terminal electrode and bottom terminal electrode to cause light generation and propagation within the vertical resonant cavity.

33. A semiconductor device according to claim 31, wherein:

the electrodes of the device are configured as terminals of a switching thyristor optical detector having an ON state whereby current flows between the top terminal electrode and bottom terminal electrode, wherein the ON state is caused by absorption of light propagating in the vertical resonant cavity.

34. A semiconductor device comprising:

an optical resonator including a closed path waveguide that supports circulating propagation of light;

a waveguide structure that is spaced from the closed path waveguide of the optical resonator to provide for evanescent-wave optical coupling therebetween;

wherein the closed path waveguide includes at least one active section and a tuning section that is spaced from the at least one active section, wherein the active section is configured to generate or absorb light that circulates in the closed path waveguide, and wherein the tuning section is configured to provide electrical control of the wavelength of the light circulating in the closed path waveguide.

35. A semiconductor device according to claim 34, wherein:

the closed path waveguide of the optical resonator and the waveguide structure are both formed in an epitaxial layer structure that includes at least one modulation doped quantum well structure with one or more quantum wells; and

the tuning section of the closed path waveguide includes a plurality of electrodes for supplying electrical signals that control charge in the one or more quantum wells of the at least one modulation doped quantum well structure of the epitaxial layer structure of the tuning section in order to control the wavelength of the light circulating in the closed path waveguide.

36. A semiconductor device according to claim 35, wherein

the tuning section of the closed path waveguide is isolated from the at least one active section by passive waveguide sections.

37. A semiconductor device comprising:

an optical resonator including a closed path waveguide that supports circulating propagation of light;

a waveguide structure that is spaced from the closed path waveguide of the optical resonator to provide for evanescent-wave optical coupling therebetween, wherein the waveguide structure has one end disposed opposite an output end; and

a reflector structure integral to said one end of the waveguide structure, wherein the reflector structure includes a Bragg-grating.

38. A semiconductor device according to claim 37, wherein:

the reflector structure includes two co-planar radio-frequency (RF) traveling wave transmission lines disposed on opposite sides of the Bragg-grating along the length of the Bragg-grating.

39. A semiconductor device according to claim 38, further comprising:

a signal source that supplies a traveling wave RF signal to the two co-planar RF traveling wave transmission lines in order to selectively control the wavelength of light that is reflected by the Bragg-grating of the reflector structure.

40. A semiconductor device according to claim 37, wherein:

the closed path waveguide of the optical resonator and the waveguide structure and the reflector structure are all formed in an epitaxial layer structure that includes at least one layer disposed above a modulation doped quantum well structure; and

the Bragg-grating is formed in the at least one layer disposed above the modulation doped quantum well structure.

41. A method of forming a patterned layer of metal that defines an aperture of an optoelectronic device realized in an integrated circuit wafer, the method comprising:

depositing and patterning a first mask on a top surface of the wafer, wherein the pattern of the first mask defines a mask feature that protects an area of the aperture;

performing an ion implant operation that forms at least one ion implant region disposed adjacent the aperture;

depositing metal such that the metal covers the top surface and the mask feature;

depositing and patterning a second mask to define a window that overlies the mask feature, wherein the window has a smaller width than width of the mask feature.

performing a first etch operation that etches through the window defined by the second mask to a depth at or near the top surface, where the first etch operation leaves behind at least one sidewall of the mask feature; and

performing a second etch operation that etches sideways and undercuts the at least one sidewall of the mask feature as well as at least one adjacent sidewall of the metal to form the aperture.

42. A method according to claim 41, wherein:

the first mask comprises a dual layer structure of oxide and nitride.

43. A method according to claim 41, wherein:

the at least one ion implant region provide for current funneling toward an active region under the aperture and/or lateral confinement of light within the active region under the aperture.

44. A method according to claim 41, wherein:

the metal comprises tungsten; and

/or

the at least one sidewall of the mask feature that results from the first etch operation has a width dimension on the order of 1-2 μ

m; and

/or

the first etch operation employs an anisotropic etching process that defines a near vertical profile for the at least one sidewall of the mask feature; and

/or

the second etch operation employs a buffer-oxide etchant.

45. An optoelectronic semiconductor device comprising:

a substrate;

an epitaxial layer arrangement formed on the substrate, wherein in the epitaxial layer arrangement includes a buffer structure and an active device structure formed on the buffer structure;

wherein the active device structure includes at least one modulation doped quantum well structure spaced from a QD-in-QW structure; and

wherein the buffer structure comprises a plurality of layer that are configured to accommodate lattice strain due to mismatch between the active device structure and the substrate.

46. An optoelectronic semiconductor device according to claim 45, wherein:

the substrate comprises a GaAs substrate;

the at least one modulation doped quantum well structure comprises at least one InGaAs quantum well formed from an alloy of InAs and GaAs that includes at least 70 percent InAs; and

the QD-in-QW structure comprises quantum dots formed from InAs and embedded within at least one InGaAs quantum well formed from an alloy of InAs and GaAs that includes at least 70 percent InAs.

47. An optoelectronic semiconductor device according to claim 46, wherein:

at least one InGaAs quantum well of the QD-in-QW structure includes a template substructure formed below an emission substructure, wherein the template substructure includes a non-graded InGaAs quantum well formed from an alloy of InAs and GaAs that includes less than 70 percent InAs, and wherein the emission substructure includes a graded InGaAs quantum well formed from an alloy of InAs and GaAs that has a maximum percentage of InAs of at least 70 percent InAs.

48. An optoelectronic semiconductor device according to claim 46, wherein:

the buffer structure comprises a plurality of layers formed from an alloy of InAs and AlAs.

49. An optoelectronic semiconductor device according to claim 48, wherein:

the buffer structure further comprises a periodic superlattice layer structure comprising a first layer formed from an alloy of AlAs and GaAs and a second layer formed from GaAs.

50. A method of fabricating an optoelectronic device realized in an integrated circuit wafer that includes a top layer overlying a doped ohmic contact layer and semiconductor layers therebelow, the method comprising:

depositing a protective layer on the top layer;

depositing and patterning a first mask on the protective layer, wherein the pattern of the first mask protects an area for an optical feature;

performing a first etch operation that etches down to the doped ohmic contact layer in order to define the optical feature that includes the top layer, wherein the first etch operation exposes the doped ohmic contact layer adjacent at least one side of the optical feature and leaves behind at least one sidewall of the optical feature;

performing an ion implant operation that forms at least one ion implant region in the semiconductor layers disposed below the exposed doped ohmic contact layer adjacent the at least one side of the optical feature;

depositing and patterning a second mask to define a window that overlies the optical feature; and

performing a second etch operation that uses the window of the second mask to expose the top layer of the optical feature.

51. A method according to claim 50, wherein:

the optical feature is selected from group consisting of an aperture, a waveguide layer of an active waveguide structure, and a waveguide layer of a passive waveguide structure.

52. A method according to claim 50, further comprising:

depositing metal such that the metal covers the optical feature;

wherein the second mask is deposited on the metal and the window defined by the second mask exposes metal that covers the optical feature; and

wherein the second etch operation removes the metal that covers the optical feature in order to expose the top layer of the optical feature.

53. A method according to claim 50, wherein:

the top layer comprises an undoped semiconductor layer; and

/or

the protective layer comprises a silicon nitride layer; and

/or

the first etch operation employs an anisotropic etching process that define a near vertical profile for the at least one sidewall of the optical feature; and

/or

the second etch operation employs a buffer-oxide etchant; and

/or

the at least one ion implant region provides for current funneling toward an active region under the optical feature and/or lateral confinement of light in the active region under the optical feature.