Patent Publication Number: US-8994004-B2

Title: Hybrid silicon optoelectronic device and method of formation

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 11/734,559, filed Apr. 12, 2007, entitled “HYBRID SILICON EVANESCENT PHOTODETECTORS,” by John E. Bowers, which is a continuation-in-part application of the following co-pending and commonly-assigned U.S. patent application: 
     Ser. No. 11/534,560, filed Sep. 22, 2006, entitled “III-V PHOTONIC INTEGRATION ON SILICON,” by John E. Bowers, which claims priority to Ser. No. 60/795,064, filed Apr. 26, 2006, entitled “III-V PHOTONIC INTEGRATION ON SILICON,” by John E. Bowers, and to Ser. No. 60/760,629, filed Jan. 20, 2006, entitled “OPTICAL GAIN AND LASING ON SILICON,” by John E. Bowers, 
     which applications are incorporated by reference herein. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     This invention was made with Government support under Grant No. W911NF-05-1-0175, awarded by the Department of Defense. The Government has certain rights in this invention. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to semiconductor devices, and, more specifically, to integration of III-V optical devices with silicon substrates and circuits. 
     2. Description of the Related Art 
     Semiconductor chip level bonded devices have found uses in several consumer and commercial applications. Typically, semiconductor devices are made from a single type of material, or different types of material are grown onto a substrate based on lattice matching and compatible crystalline structures. Devices manufactured from III-V materials are typically grown on gallium arsenide or other compound semiconductor substrates. These devices are difficult to integrate with electronic devices fabricated on silicon. 
     However, there are many advantages to integrating electronic and photonic devices on a single substrate. Passive photonic devices such as arrayed waveguide routers (AWG) are commonly fabricated on silicon. Some active photonic devices have been demonstrated on silicon such as modulators and Raman lasers. However, most active photonic devices require single crystal material, which is difficult to grow on silicon because of the large lattice mismatch between the semiconductor with the proper bandgaps and silicon itself. The problem with the present discrete photonic devices is that the performance can be improved with integration, and the cost and size is much smaller. Silicon is a preferred semiconductor material, because it is easily processed, it is readily available for reasonable cost and high quality, and complex VLSI electronic circuits are readily available. However, silicon-based modulators or lasers or other photonic devices are not as efficient at light emission or absorption as their III-V based counterparts. It can be seen, then, that there is a need in the art for a larger scale integration between III-V materials and silicon. 
     SUMMARY OF THE INVENTION 
     To minimize the limitations in the prior art, and to minimize other limitations that will become apparent upon reading and understanding the present specification, the present invention provides a technology for making photonic integrated circuits on silicon. By bonding a wafer of III-V material as an active region to silicon and removing the substrate, the lasers, amplifiers, modulators, and other devices can be processed using standard photolithographic techniques on the silicon substrate. The coupling between the silicon waveguide and the III-V gain region allows for integration of low threshold lasers, tunable lasers, and other photonic devices and integrated circuits with Complimentary Metal Oxide Semiconductor (CMOS) integrated circuits. 
     A photodetector in accordance with the present invention comprises a silicon-on-insulator (SOI) structure resident on a first substrate, the SOI structure comprising a passive waveguide, and a III-V structure bonded to the SOI structure, the III-V structure comprising a quantum well region, a hybrid waveguide, coupled to the quantum well region and the SOI structure adjacent to the passive waveguide, and a mesa, coupled to the quantum well region, wherein when light passes through the hybrid waveguide, the quantum well region detects the light and generates current based on the light detected. Such a photodetector further optionally includes the quantum well region is an AlGaInAs quantum well region, the hybrid waveguide is tilted with respect to the passive waveguide, the hybrid waveguide is tilted by seven degrees with respect to the passive waveguide, the photodetector is part of an array of photodetectors, the photodetector is integrated with at least one other electronic device, the at least one other electronic device being a CMOS device, the mesa is implanted with protons, and the coupling between the passive waveguide and the hybrid waveguide is evanescent. 
     An integrated laser/photodetector device in accordance with the present invention comprises a semiconductor-on-insulator (SOI) structure resident on a first substrate, the SOI structure comprising a passive waveguide, a semiconductor structure bonded to the SOI structure, the semiconductor structure comprising a quantum well region, a hybrid waveguide, coupled to the quantum well region and the SOI structure adjacent to the passive waveguide, and a mesa, coupled to the quantum well region, and a lasing device, coupled to the hybrid waveguide, for providing light to the hybrid waveguide to generate current in the photodetector. 
     Such a device further optionally includes the coupling between the hybrid waveguide and the passive waveguide is evanescent, the SOI structure comprises a silicon substrate, the semiconductor structure comprises a III-V semiconductor material, the lasing device comprises a ring laser, the lasing device is coupled to the photodetector via a directional coupler, and at least one additional photodetector coupled to the lasing device. 
     Other features and advantages are inherent in the system disclosed or will become apparent to those skilled in the art from the following detailed description and its accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the drawings in which like reference numbers represent corresponding parts throughout: 
         FIG. 1  is a side view of a photonic integrated circuit in accordance with the present invention; 
         FIG. 2  illustrates a cross-sectional view of the offset quantum well absorption region in accordance with the present invention; 
         FIG. 3  illustrates another view of the quantum well region shown in  FIG. 2  in accordance with the present invention; 
         FIG. 4  illustrates the confinement factor versus the width and height of the silicon core in accordance with the present invention; 
         FIG. 5  illustrates a processed chip with different devices on a single wafer in accordance with the present invention; 
         FIG. 6  illustrates an optical buffer memory structure in accordance with the present invention; 
         FIG. 7  illustrates an integrated silicon transmitter photonics chip in accordance with the present invention; 
         FIGS. 8-10  illustrate a hybrid silicon evanescent waveguide photodetector structure in accordance with the present invention; and 
         FIGS. 11 ,  12 A and  12 B illustrate a racetrack laser/photodetector in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following description, reference is made to the accompanying drawings which form a part hereof, and which is shown, by way of illustration, several embodiments of the present invention. It is understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. 
     Overview 
       FIG. 1  is a side view of a photonic integrated circuit in accordance with the present invention. 
     Device  100  is shown, with wafer  102 , film  103 , waveguide layer  104 , modulator/mode converter  106 , gain region  108 , and photodetector  110  as shown. DBR reflector  112  are also shown. 
     Wafer  102  is typically a silicon CMOS wafer, but can be other materials, such as glass, as desired. Film  103  is typically silicon oxide, but can also be a nitride or silicon oxynitride if desired without departing from the scope of the present invention. Waveguide layer  104  is on film  103 , and is the silicon waveguide layer for device  100 . Modulator/mode converter  106 , tunable laser  108 , photodetector  110 , and rib waveguides  112  are typically Indium Gallium Arsenide Phosphide (InGaAsP), but can be other materials, such as GaInAsN, or other III-V or II-VI materials, without departing from the scope of the present invention. 
     A thin film of InGaAsP is deposited on a Semiconductor-On-Insulator (SOI) waveguide. This allows for evanescent coupling of the light in the SOI waveguide  104  to the quantum wells in the III-V material  108 . DBR reflectors  112  are patterned for reflection within the waveguide. 
     Lateral Structure 
       FIG. 2  illustrates a cross-sectional view of the offset quantum well gain region in accordance with the present invention. 
     Device  200  comprises wafer  202 , oxide layer  204 , semiconductor layer  206 , and spacer layer  208 , which is bonded to semiconductor layer  206  at bonding interface  210 . Within semiconductor layer  206  resides gaps  212 , typically air gaps  212 . On spacer layer  208  resides the quantum structure  214 , and then bulk semiconductor layer  216 . Contact  218  and contacts  220  are also shown. 
     Typically, wafer  202  is a silicon substrate, oxide layer  204  is silicon oxide, and semiconductor layer  206  is silicon, which together comprise a SOI structure. Gaps  212  form the sides of SOI waveguides. Gaps  212  (also known as cladding) can be air gaps, as well as refilled silicon oxide, silicon oxynitride, or silicon nitride, or other materials, without departing from the scope of the present invention. Further, the shape of gaps  212 , when viewed from the top, can be linear, or in a circular or ring shape, or in other shapes, without departing from the scope of the present invention. 
     Spacer layer  208  is a semiconductor material, typically a III-V material, typically Indium Phosphide (InP), but can be other compound semiconductor materials if desired. The compound semiconductor layer  214  typically comprises a Multiple Quantum Well (MQW) layer and Separated Confinement Heterostructure (SCH) layers, as described in  FIG. 3 . Bulk semiconductor layer  216  is also typically InP, but can be other semiconductor materials, typically III-V semiconductor materials, without departing from the scope of the present invention. 
     Spacer layer  208  is typically bonded to semiconductor layer  206  at interface  210 . The bonding technique used is described in the art, in, e.g., U.S. Pat. Nos. 6,074,892, 6,147,391, 6,130,441, and 6,465,803, which are incorporated by reference herein, and further described in the appendices attached to the present invention, which are incorporated by reference herein. Additional bonding to create additional layers are also possible within the scope of the present invention, which would create additional interfaces  210  within device  200 . 
     Layer  216  may also comprise a grating which would create a distributed feedback laser within device  200 , a grating in the oxide layer  204  to create a distributed Bragg reflector (DBR) laser, or other layers or components to create other optical lasing devices without departing from the scope of the present invention. 
       FIG. 3  illustrates a detailed view of the quantum well region shown in  FIG. 2  in accordance with the present invention. 
     Compound semiconductor region  214  comprises an SCH layer  300 , a MQW layer  302 , and an SCH layer  304 . Typically, three to five quantum well layers are present in MQW layer  302 , but a larger or smaller number of quantum well layers or bulk layers can be present without departing from the scope of the present invention. Further, the core portion of semiconductor layer  206  has a height  306  and a width  308 , which dimensions determine the confinement factor of the device  200 . Further, the thickness of each of the layers in the MQW layer  302  also play a part in the confinement factor for a device  200  made in accordance with the present invention. 
     Confinement Factor 
       FIG. 4  illustrates the confinement factor versus the width and height of the silicon core in accordance with the present invention. 
     The graph of  FIG. 4  shows the confinement factor  400  versus the width  308 , shown on y-axis  402 , of the silicon core portion of semiconductor layer  206 . For a range of heights  306 , the confinement factor of the silicon core, shown as lines  404 , and for a range of heights  306 , the confinement factor  400  of the multiple quantum well region varies as a monotonic function of width  402 . As the height of the core gets higher, the confinement factor  400  within the waveguide goes up; as the height of the core goes up, the confinement factor in the MQW layers  406  goes down. 
     Fabrication and Integration of Separate Devices 
     Typically, a chip-level bonding approach is used to bond one type of material to another. The chip-level bonding approach works well for discrete devices, however, alignment is typically an issue. There are some devices, such as integrated optical amplifiers, that are difficult to fabricate using a chip-level approach because of reflections at the interface between the III-V layer and the silicon substrate. 
     However, the present invention contemplates using a wafer-level bonding approach, where a III-V wafer is bonded to a silicon wafer, the III-V substrate is removed, and the III-V layers are then processed into various types of devices. 
       FIG. 5  illustrates a processed chip with different devices on a single wafer in accordance with the present invention. 
     As shown in  FIG. 5 , many different types of devices can be integrated on a single wafer or chip using the process of the present invention. For example, detector pre-amplifier electronics, the detector array, a laser or modulator, drive electronics, and memory/processing circuits can now all reside on a single piece of semiconductor substrate, because the qualities of the silicon that are desirable, e.g., avalanche gain, is now electrically bonded to a material that is a better absorber than silicon. 
       FIG. 6  illustrates an optical buffer memory structure in accordance with the present invention. 
       FIG. 7  illustrates an integrated silicon transmitter photonics chip in accordance with the present invention. 
     Chip  1200  comprises ring lasers  1202 - 1208 , which are evanescent lasers. Each ring laser  1202 - 1208  can produce different wavelengths if desired. Ring lasers  1202 - 1208  have their waveguides resident in chip  1200 , which is typically silicon, and the gain region in the bonded region  1210 , which is typically a III-V material. 
     Ring lasers  1202 - 1208  are then coupled to SOI waveguides  1212 - 1218  respectively, which are coupled to modulators  1220 - 1226 . Modulators  1220 - 1226  are resident in the chip  1200 , which, again, is typically silicon, but can be other materials without departing from the scope of the present invention. 
     Modulators  1220 - 1226  are then coupled via SOI waveguides to multiplexer  1228 , which has an output  1230 . Output  1230  comprises a signal which contains all of the wavelengths produced by ring lasers  1202 - 1208 . Additional circuitry can be provided to selectively eliminate one or more of the ring lasers  1202 - 1208  wavelengths from being included in output  1230 . 
     As seen in  FIG. 7 , the evanescent coupling of the present invention can be performed at the wafer level, partial wafer level, or die level, depending on the application or desired device, which provides for selective integration of III-V materials or other materials with a silicon platform. 
     Waveguide Photodetector 
       FIGS. 8-10  illustrate a hybrid silicon evanescent waveguide photodetector structure in accordance with the present invention. 
     Overview 
       FIG. 8  shows a waveguide photodetector using a hybrid waveguide structure consisting of AlGaInAs quantum wells bonded to a silicon waveguide. The light in the hybrid waveguide is absorbed by the AlGaInAs quantum wells under reverse bias. The photodetector has a fiber coupled responsivity of 0.31 A/W with an internal quantum efficiency of 90% over the 1.5 micron wavelength range. This photodetector structure can be integrated with silicon evanescent lasers for power monitors or integrated with silicon evanescent amplifiers for preamplified receivers. 
     The present invention comprises a hybrid silicon evanescent waveguide photodetector, which has excellent quantum efficiency, low dark current, and an extended wavelength range over previously fabricated devices. For example, experimental data has shown that a detector in accordance with the present invention operates with a responsivity of 1.1 A/W, a quantum efficiency of 90% covering a wavelength range up to 1600 nm, and dark current of less than 100 nA at a reverse bias of 2 V. 
     Device Structure and Fabrication 
       FIG. 8  shows detector  1300 , with SOI region  1302  and III-V region  1304 . The SOI region  1302  is bonded to the III-V region  1304  as described herein. The hybrid silicon evanescent photodetector  1300  comprises of AlGaInAs quantum wells  1306  bonded to a silicon waveguide  1308 . As light propagates through the hybrid waveguide  1308 , it is absorbed in the III-V region generating electron hole pairs. When the device is under reverse bias, the carriers are swept away as shown with the three arrows  1310 ,  1312 , and  1314 . The input to the photodetector is a passive silicon waveguide  1308 . At the junction of the hybrid waveguide  1316  and the passive silicon waveguide  1308 , the III-V region of the hybrid waveguide  1316  is tilted by 7° to reduce the reflection at the passive waveguide  1308  transition, as shown in  FIG. 9 . Other angles can be used without departing from the scope of the present invention; such angles may be required for different materials systems or for other reasons based on the design and desired output of the device  1300 . 
     The silicon waveguide  1308  is typically formed on a &lt;100&gt; surface of an undoped silicon-on-insulator (SOI) substrate  1318  with a 1 micron thick buried oxide  1320  using standard projection photolithography and Cl 2 /Ar/HBr-based plasma reactive ion etching. The silicon waveguide  1308  is typically fabricated with a final height of 0.69 microns, width of 2 microns, and slab thickness of 0.19 microns, but other heights, widths, and slab thicknesses can be used without departing from the scope of the present invention. 
     The III-V epitaxial structure  1304 , including absorbing quantum well layers  1306 , is typically grown on an InP substrate. The photodetector  1300  active absorbing region  1306  typically consists of eight compressively strained quantum wells (0.85%), and nine tensile strained barriers (−0.55%). The total thickness of the undoped quantum well region  1306  is typically 0.146 μm. This III-V structure  1304  is then transferred to the patterned silicon wafer through low temperature oxygen plasma assisted wafer bonding, which typically uses temperatures at approximately 300° C. annealing temperature under vacuum for approximately 12 hours. Different temperatures and conditions can be used without departing from the scope of the present invention. 
     After removal of the InP substrate, mesas are formed by dry-etching the p-type layers  1322 , and a subsequent wet etch of the quantum well layer  1306  to the n-type layers  1316  is performed. Contacts  1324 , typically made from a Ni/Au/Ge/Ni/Au alloy, although other materials can be used, are deposited onto the exposed n-type InP layer  1316 , typically 10 μm away from the center of the silicon waveguide  1308 . P contacts  1326  are then deposited on the center of the mesas of the absorber region. 
     After proton implantation on the two sides of the p-type mesa, Ti/Au p-probe pads  1328  are deposited. A 450 nm thick SiN x  dielectric layer  1330  is used for the electrical isolation between the p-probe pad  1328  and the n-type InP layer portion of  1316 . The III-V mesa region on the silicon input and output waveguide is then dry etched using the same process used during the p-mesa definition, exposing the passive input and output silicon waveguides. 
     The sample is diced with a silicon facet angle of 7° as shown in  FIG. 9 . After the facets are polished, an antireflection coating of Ta 2 O 5  (˜5% of reflectivity) is deposited to the silicon waveguide  1308  facets. The final length of the hybrid photodetector  1300  is typically 400 μm. A SEM image of the final fabricated hybrid photodetector and a close view of the junction at the device input are shown in  FIGS. 10 and 11 , respectively. The silicon confinement factor is calculated to be 65% with the fabricated device dimensions while the quantum well  1306  confinement is calculated to be 4%. 
     The measured TE responsivity of the typical device according to the present invention at 1550 nm is 0.31 to 0.32 A/W, and is roughly constant over a range of bias conditions from 0.5V to 3V. At a reverse bias of 3V the quantum efficiency is ˜90% at 1550 nm. From measurements of output power from a silicon output waveguide, the TE modal absorption coefficient is estimated to be 75 cm −1 , which corresponds to a material TE absorption coefficient of 1875 cm −1  at zero bias assuming a 4% quantum well confinement factor. TM responsivity was measured at 0.23 A/W at a wavelength of 1550 nm, which is typically lower than TE responsivity because of the orientation of the compressively strained quantum wells. 
     The dark current is typically 50 nA to 200 nA with a bias range of −1V to −4 V, and breakdown occurs when the reverse bias exceeds 16 V. The exponential increase of dark current as reverse bias is increased indicates that the dark current is likely dominated by band-to-band tunneling. The diode ideality factor (n) under small forward bias (&lt;0.5 V) is measured to be 2, indicating that the recombination current in the quantum well region is dominant. The 11 ohm series resistance beyond diode turn-on (0.8 V) is due to the thin n-layer and the contact resistances. 
     The frequency response of the device was measured by a network component analyzer with a 50Ω termination. The bandwidth of the device is 470 MHz at a reverse bias of 4 V. The measured bandwidth agrees with a RC limited bandwidth of 482 MHz, and the frequency response is limited by the large pad and detector resistance. The capacitance of the mesa can be reduced by reducing the width and length of the III-V mesa. The mesa capacitance can also be reduced by modifying the proton implant profile such that it extends through the top InGaAs p contact layer  1326  of the mesa. 
     Racetrack Laser/Photodetector 
       FIGS. 11 ,  12 A and  12 B illustrate a racetrack laser/photodetector in accordance with the present invention. 
     The present invention also contemplates a racetrack resonator laser integrated with a plurality of photodetectors on the hybrid AlGaInAs-silicon evanescent device platform. Unlike previous demonstrations of hybrid AlGaInAs-silicon evanescent lasers and photodetectors, the present invention demonstrates an on-chip racetrack resonator laser that does not rely on facet polishing and dicing in order to define the laser cavity. 
     The laser runs continuous-wave (c.w.) at a typical wavelength of 1590 nm and a typical threshold of 175 mA. The laser also has a typical maximum total output power of 29 mW and a typical maximum operating temperature of 60 C. The output of the laser light is directly coupled into a pair of on-chip hybrid AlGaInAs-silicon evanescent photodetectors used measure the laser output. 
     Device Structure and Fabrication 
       FIG. 11  illustrates the hybrid AlGaInAs-silicon evanescent device in a cross-sectional view. The device  1600  is fabricated using an AlGaInAs quantum well  1602  epitaxial structure  1604  that is bonded to a low-loss silicon rib waveguide  1606 . The silicon rib waveguide  1606  is typically formed on the &lt;100&gt; surface of an undoped silicon-on-insulator (SOI) substrate  1608  with a 1 micron thick buried oxide  1610  using standard projection photolithography and plasma reactive ion etching techniques. The silicon waveguide  1606  is typically fabricated with a final height, width, and rib-etch depth of 0.69 microns, 1.65 microns, and 0.5 microns, respectively, although other heights, widths, and rib-etch depths can be used without departing from the scope of the present invention. 
     The III-V structure  1612  comprising epitaxial structure  1604  is transferred to the patterned silicon wafer  1614  through a low temperature oxygen plasma assisted wafer bonding process described hereinabove. 
     After InP substrate removal, 10 μm (typical) wide mesas  1604  are formed using photolithography and by plasma reactive ion etching through the p-type layers and selective wet etching of the quantum well layers  1602  to the n-type layers. Ni/AuGe/Ni/Au alloy n-contacts  1616  are deposited onto the exposed n-type InP layers  1618  on both sides of the mesa  1604 . Pd/Ti/Pd/Au p-contacts  1620  are then deposited on the approximate centers of the mesas  1604 . The p-region  1622  on the two sides of the mesa are implanted with protons (H+) which electrically insulates the p-type-InP resulting in a ˜4 micron wide p-type current channel down through the non conductive p-type mesa  1604 , preventing lateral current spreading in the p-type mesa  1604 . The electrical current flows through the center of the mesa to achieve a large overlap with the optical mode  1624 . 
     The laser layout is shown in  FIG. 12A , and a SEM micrograph view of the laser layout is shown in  FIG. 12B . The laser layout  1700  comprises a racetrack ring resonator  1702  having n-metals  1701  and p-metal  1703 , with a typical straight waveguide length of 700 microns. A directional coupler  1704  is formed on the bottom arm by placing a bus waveguide 0.5 micron away from the racetrack  1702 . Four device  1700  designs were fabricated with varying ring radii, and coupler  1704  interaction lengths  1706 (L interaction ). 
     Table 1 shows the device  1700  layout breakdown with the corresponding cavity lengths (L cavity ) and the computed coupling percentage to the bus waveguide  1606 . The laser power is collected into the two photodetectors  1600 . These photodetectors  1600  have the same waveguide architecture as the hybrid laser  1700 , the only difference being that they are reverse biased to collect photo-generated carriers. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Ring dimensions and coupling parameters 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                   
                 Computed 
               
               
                   
                   
                   
                   
                 Feedback 
               
               
                   
                 Radius 
                 L cavity   
                 L interaction   
                 Coupling 
               
               
                   
                   
               
               
                   
                 200 μm 
                 2656 μm 
                 600 μm 
                  3% 
               
               
                   
                   
                   
                 400 μm 
                 12.6%   
               
               
                   
                 100 μm 
                 2028 μm 
                 300 μm 
                 36% 
               
               
                   
                   
                   
                 100 μm 
                 85% 
               
               
                   
                   
               
            
           
         
       
     
     The integration of racetrack laser  1700  with photodetectors  1600  on the hybrid silicon evanescent device platform demonstrates the potential to realize practical photonic integrated circuits on a silicon substrate  1608 . These two types of photonic devices are fabricated on a single active region design showing the flexibility of the hybrid silicon evanescent device platform of the present invention. On-chip testing and characterization of the laser simplifies the testing by eliminating facet polishing and characterization uncertainties caused by coupling losses. 
     The photodetectors  1600  could be PIN detectors, which produce one electron-hole pair for each incident photon. The photodetector could be an avalanche photodiode where the electrons (or holes) generated in the waveguide absorber are multiplied in the avalanche region. This is particularly advantageous when the avalanche layer is silicon, which is known to have a large ratio of electron to hole ionization coefficients, and consequently, is an excellent material for an avalanche photodiode. 
     CONCLUSION 
     In summary, embodiments of the invention provide methods and for making an optical device on silicon. The present invention can be used for lasers, modulators, amplifiers, and photodetectors, and devices that use combinations of these devices, such as wavelength converters, channel selectors, 3R regenerators, buffer memories, etc. 
     A photodetector in accordance with the present invention comprises a silicon-on-insulator (SOI) structure resident on a first substrate, the SOI structure comprising a passive waveguide, and a III-V structure bonded to the SOI structure, the III-V structure comprising a quantum well region, a hybrid waveguide, coupled to the quantum well region and the SOI structure adjacent to the passive waveguide, and a mesa, coupled to the quantum well region, wherein when light passes through the hybrid waveguide, the quantum well region detects the light and generates current based on the light detected. Such a photodetector further optionally includes the quantum well region is an AlGaInAs quantum well region, the hybrid waveguide is tilted with respect to the passive waveguide, the hybrid waveguide is tilted by seven degrees with respect to the passive waveguide, the photodetector is part of an array of photodetectors, the photodetector is integrated with at least one other electronic device, the at least one other electronic device being a CMOS device, the mesa is implanted with protons, and the coupling between the passive waveguide and the hybrid waveguide is evanescent. 
     An integrated laser/photodetector device in accordance with the present invention comprises a semiconductor-on-insulator (SOI) structure resident on a first substrate, the SOI structure comprising a passive waveguide, a semiconductor structure bonded to the SOI structure, the semiconductor structure comprising a quantum well region, a hybrid waveguide, coupled to the quantum well region and the SOI structure adjacent to the passive waveguide, and a mesa, coupled to the quantum well region, and a lasing device, coupled to the hybrid waveguide, for providing light to the hybrid waveguide to generate current in the photodetector. 
     Such a device further optionally includes the coupling between the hybrid waveguide and the passive waveguide is evanescent, the SOI structure comprises a silicon substrate, the semiconductor structure comprises a III-V semiconductor material, the lasing device comprises a ring laser, the lasing device is coupled to the photodetector via a directional coupler, and at least one additional photodetector coupled to the lasing device. 
     The foregoing description of the preferred embodiment of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but by the claims attached hereto and the full breadth of equivalents to the claims.