US20180301568A1 - Rapid melt growth photodetector - Google Patents
Rapid melt growth photodetector Download PDFInfo
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- US20180301568A1 US20180301568A1 US15/486,810 US201715486810A US2018301568A1 US 20180301568 A1 US20180301568 A1 US 20180301568A1 US 201715486810 A US201715486810 A US 201715486810A US 2018301568 A1 US2018301568 A1 US 2018301568A1
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- 229910052732 germanium Inorganic materials 0.000 claims abstract description 126
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims abstract description 126
- 239000000463 material Substances 0.000 claims abstract description 44
- 239000000758 substrate Substances 0.000 claims abstract description 12
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 41
- 229910052710 silicon Inorganic materials 0.000 claims description 41
- 239000010703 silicon Substances 0.000 claims description 41
- 238000000034 method Methods 0.000 description 20
- 230000007547 defect Effects 0.000 description 18
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- 239000013078 crystal Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 229910000577 Silicon-germanium Inorganic materials 0.000 description 2
- LEVVHYCKPQWKOP-UHFFFAOYSA-N [Si].[Ge] Chemical compound [Si].[Ge] LEVVHYCKPQWKOP-UHFFFAOYSA-N 0.000 description 2
- 239000002800 charge carrier Substances 0.000 description 2
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- 230000005540 biological transmission Effects 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0232—Optical elements or arrangements associated with the device
- H01L31/02327—Optical elements or arrangements associated with the device the optical elements being integrated or being directly associated to the device, e.g. back reflectors
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4295—Coupling light guides with opto-electronic elements coupling with semiconductor devices activated by light through the light guide, e.g. thyristors, phototransistors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
- H01L31/0352—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
- H01L31/035272—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions characterised by at least one potential jump barrier or surface barrier
- H01L31/03529—Shape of the potential jump barrier or surface barrier
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
- H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
- H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
- H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12035—Materials
- G02B2006/12061—Silicon
Definitions
- the present exemplary embodiments pertain to optoelectronic devices and, more particularly, to waveguide photodetectors that convert optical signals into electrical signals.
- optical waveguides provide a transmission channel for guiding an optical signal produced by a light source, e.g., a laser, at one end of the system to a detector, e.g., a photodetector, at the other end of the system.
- the photodetector material an active region, absorbs energy from the photons of the transmitted optical signal, which, in response, excites charge carriers, e.g., electrons and holes.
- charge carriers e.g., electrons and holes.
- the excited charge carriers With the application of a reverse bias voltage, the excited charge carriers are attracted to contacts on the photodetector, thereby creating an electrical current that corresponds to the optical signal. In this manner, the photodetector converts an optical signal into an electrical signal.
- germanium Due to its potential for being grown on top of silicon, germanium is an appropriate choice for a photodetector.
- a lattice constant refers to the distance between unit cells in a crystal lattice.
- the lattice constant of germanium is not perfectly matched with the lattice constant of silicon; the lattice constant of germanium is slightly larger than that of silicon.
- the mismatch between the lattice constants of germanium and silicon presents problems for using a regular epitaxial growth (“EPI”) technique for growing crystals.
- EPI epitaxial growth
- EPI epitaxial growth
- SEG buffer layer and post-process after selective epitaxial growth
- the second method is using a rapid melt growth (“RMG”) technique. Between these two methods, RMG has better process compatibility but has a limitation on the structures that can be constructed.
- single crystal germanium is not grown directly on top of the silicon. Rather, poly-germanium or amorphous germanium is deposited on an insulator that has an opening (“seed window”) to an underlying silicon layer. An insulator, such as a nitride, is deposited to surround the poly-germanium or amorphous germanium.
- the RMG method requires a micro-crucible formed by the insulator surrounding the deposited poly-germanium or amorphous germanium which causes melting and recrystallization of the germanium when subjected to anneal.
- Optical detectors in a CMOS compatible process sequence can be accomplished inexpensively with an RMG germanium photodetector.
- RMG photodetectors have been built in silicon compatible processes but suffer from a couple of difficulties.
- One difficulty is that the silicon seed region contaminates the germanium photodetector resulting in a silicon germanium detector rather than a pure crystalline germanium photodetector. This can result in poor responsivity of the photodetector.
- Another difficulty is that the melting and subsequent recrystallization of the germanium photodetector can result in the formation of defects near the end of the photodetector affecting the yield and responsivity of the photodetector.
- a photodetector comprising: a waveguide extending over a substrate, the waveguide comprising a waveguide material; an insulating layer formed over the waveguide, the insulating layer having an opening exposing the waveguide; a photodetector layer formed over the insulating layer and into the opening so as to make contact with the waveguide, the photodetector layer having a first end at the opening and a second end distal from the opening, the photodetector layer being a gradient material of the waveguide material and germanium wherein a waveguide material portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end; a photodetector region at the second end; and a photodetector layer extension extends at an angle from
- a photodetector comprising: a waveguide extending over a substrate, the waveguide comprising silicon; an insulating layer formed over the waveguide, the insulating layer having an opening exposing the waveguide; a linear photodetector layer formed over the insulating layer and into the opening so as to make contact with the waveguide, the linear photodetector layer having a first end at the opening and a second end at the terminus of the linear photodetector layer, the photodetector layer being a gradient material of the silicon and germanium wherein a silicon portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end; a photodetector at the terminus of the linear photodetector layer; and a photodetector layer extension extends at an angle from the terminus of the linear photodet
- a photodetector comprising: a waveguide extending over a substrate, the waveguide comprising silicon; an insulating layer formed over the waveguide, the insulating layer having an opening exposing the waveguide; a photodetector layer formed over the insulating layer and into the opening so as to make contact with the waveguide, the photodetector layer having a first end at the opening and a second end at a photodetector region formed in the photodetector layer, the photodetector layer being a gradient material of the silicon and germanium wherein a silicon portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end; a photodetector layer extension extends at an angle from the linear photodetector layer such that the photodetector layer and the photodetector layer extension
- a photodetector comprising: a waveguide extending over a substrate, the waveguide has an incoming portion that joins with a main portion, the incoming portion being at an angle with respect to the main portion; an insulating layer formed over the waveguide, the insulating layer having an opening exposing the main portion of the waveguide; a photodetector layer formed over the insulating layer and into the opening so as to make contact with the main portion of the waveguide, the photodetector layer having a first end at the opening and a second end spaced from the first end, the photodetector layer being a gradient material of the silicon and germanium wherein a silicon portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end; the main portion of the waveguide extends underneath the photodetector layer from where the main portion
- a photodetector comprising: a silicon waveguide extending over a substrate, the waveguide has an incoming portion that joins with a main portion, the incoming portion being at an angle with respect to the main portion; an insulating layer formed over the waveguide, the insulating layer having an opening exposing a silicon seed; a photodetector layer formed over the insulating layer and into the opening so as to make contact with the silicon seed, the photodetector layer having a first end at the opening and a second end spaced from the first end, the photodetector layer being a gradient material of the silicon and germanium wherein a silicon portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end; the main portion of the waveguide extends underneath the photodetector layer from where the main portion of the waveguide join
- FIG. 1 is a plan view of an embodiment of a germanium photodetector.
- FIG. 2 is a cross sectional view of the germanium photodetector of FIG. 1 in the direction of arrows 2 - 2 .
- FIG. 3 is an enlarged plan view of a section of the germanium photodetector of FIG. 1 circumscribed by the dashed rectangle in FIG. 1 .
- FIG. 4A is a plan view of another embodiment of a germanium photodetector and FIG. 4B is a plan view of a modified version of the germanium photodetector of FIG. 4A .
- FIG. 5 is a plan view of another embodiment of a germanium photodetector.
- FIG. 6 is a plan view of another embodiment of a germanium photodetector.
- FIG. 7 is a plan view of another embodiment of a germanium photodetector.
- FIG. 8 is a plan view of another embodiment of a germanium photodetector.
- FIG. 9 is a plan view of another embodiment of a germanium photodetector.
- FIG. 10 is a plan view of another embodiment of a germanium photodetector
- FIG. 11 is a plan view of another embodiment of a germanium photodetector.
- One advantage is the creation of a photodetector with a silicon-rich region away from the incident light.
- Another advantage is a germanium-rich region near the incidence of the optical signal.
- a further advantage is a defect gettering region out of the path of the optical signal.
- FIG. 1 there is a plan view of an exemplary embodiment of a germanium photodetector 10 .
- the germanium photodetector 10 includes a waveguide 12 , usually silicon, with the incoming signal, indicated by arrow 14 , as coming in to the germanium photodetector 10 from the right.
- the photodetector layer 16 makes contact with the underlying waveguide 12 through seed window 18 .
- the right side of the photodetector layer 16 indicated by dashed oval 16 A, contains a photodetector diode.
- Surrounding the photodetector layer 16 is an insulator 20 , such as nitride.
- Surrounding the germanium photodetector 10 may be an oxide (not shown).
- the formation of the germanium photodetector 10 may be accomplished in a CMOS (Complementary Metal Oxide Semiconductor) manufacturing line. It has been found that the exemplary embodiments formed by a CMOS process minimize the difficulties of the prior art with respect to contamination of the germanium and the formation of defects.
- CMOS Complementary Metal Oxide Semiconductor
- germanium photodetector 10 taken in the direction of arrows 2 - 2 in FIG. 1 .
- the germanium photodetector 10 may be formed on a semiconductor base 22 , such as silicon, followed by a buried oxide layer 24 , the waveguide 12 , an insulator layer 26 , such as a nitride, the photodetector layer 16 and insulator 20 .
- the photodetector layer 16 has a portion 28 which extends through seed window 18 to contact the waveguide 12 .
- the germanium photodetector 10 may be formed by a process that includes forming the waveguide 12 on the buried oxide layer 24 followed by the insulator 26 .
- the seed window 18 may be formed in the insulator 26 .
- poly-germanium or amorphous germanium may be deposited, including in the seed window 18 , followed by patterning to form the photodetector layer 16 .
- the photodetector layer 16 may have a width 40 as indicated in FIG. 1 in the range of 1 to 5 ⁇ m, for example a width of 2.5 ⁇ m.
- the germanium photodetector layer 16 may be encapsulated with the insulator 20 followed by heating to at least the melting point of germanium according to the RMG process.
- a gradient of silicon germanium is formed.
- the mole fraction of silicon is highest at the seed window 18 and gradually decreases to zero or near zero at the photodetector diode 16 A.
- the mole fraction of germanium is lowest at the seed window and gradually increases to 100% or nearly 100% at the photodetector diode 16 A.
- the mole fraction of germanium at the left edge 16 B of the photodetector diode 16 A should be at least 95%.
- the photodetector layer 16 further includes one or more photodetector layer extensions 30 .
- the photodetector layer extensions may have a length 42 indicated in FIGS. 1 of 1 to 10 ⁇ m, for example a length of 3 ⁇ m.
- An advantage of the photodetector extensions 30 is that defects that may ordinarily form at the end 16 C of the photodetector layer 16 are now pushed into the photodetector layer extensions 30 .
- the photodetector layer 16 within photodetector diode 16 A is now free of these defects so that the yield and responsivity of the photodetector diode 16 A is improved.
- One portion 32 of the photodetector diode 16 A may be n doped and metal contacts 34 formed while a second portion 36 may be p doped and metal contacts 38 formed.
- the insulator 20 may be optionally removed for doping of the photodetector diode 16 A after the RMG process to minimize doping implant energy. If the insulator 20 remains in place, the metal contacts 34 may be formed by locally etching through the insulator 20 and then depositing metal for the metal contacts 34 .
- photodetector layer extensions 30 which angle off to the side of the photodetector layer 16 .
- the photodetector layer extensions 30 are shown as being perpendicular to photodetector layer 16 but lesser or greater angular extensions may also be formed.
- the dashed lines indicate where the photodetector layer 16 ends and the photodetector layer extensions 30 begin.
- germanium photodetector 400 is illustrated which is similar to germanium photodetector 10 except that germanium photodetector 400 has different photodetector layer extensions 402 .
- the photodetector layer extensions 402 include photodetector layer extension portions 404 which angle off to the side of photodetector layer 16 and photodetector layer extension portions 406 which angle off to the side of photodetector layer extension portions 404 .
- photodetector layer extension portions 406 may be parallel to photodetector layer 16 .
- germanium photodetector 400 has been modified, now germanium photodetector 400 ′, in that the photodetector layer extension portions 406 have been increased in length and now shown as photodetector layer extension portions 406 ′.
- germanium photodetectors 400 , 400 ′ An advantage of germanium photodetectors 400 , 400 ′ is that any defects during the recrystallization of the germanium are pushed further past the end 16 C of the germanium photodetector layer 16 into the photodetector layer extensions 402 .
- germanium photodetector 500 is illustrated which is similar to germanium photodetector 10 except that germanium photodetector 500 has different photodetector layer extensions 502 .
- the photodetector layer extensions 502 include photodetector layer extension portions 504 which angle off to the side of photodetector layer 16 and photodetector layer extension portions 506 which angle off to the side of photodetector layer extension portions 504 .
- photodetector layer extension portions 506 may be parallel to photodetector layer 16 .
- Germanium photodetector 500 may include additional photodetector layer extensions 508 which may angle off to the side of photodetector layer extensions 506 .
- germanium photodetector 500 An advantage of germanium photodetector 500 is that any defects during the recrystallization of the germanium are pushed further past the end 16 C of the germanium photodetector layer 16 into the photodetector layer extensions 502 .
- germanium photodetector 600 is illustrated which is similar to germanium photodetector 10 except that germanium photodetector 600 has a different photodetector layer extension 602 .
- the photodetector layer extension 602 curves off to one side of photodetector layer 16 .
- the photodetector layer extension 602 may deviate to one side 44 as indicated in FIG. 6 by 1 to 10 ⁇ m, for example 5 ⁇ m.
- germanium photodetector 600 An advantage of germanium photodetector 600 is that any defects during the recrystallization of the germanium are pushed further past the end 16 C of the germanium photodetector layer 16 into the photodetector layer extensions 602 .
- germanium photodetectors 10 , 400 , 400 ′, 500 all had photodetector layer extensions 30 , 402 , 402 ′, 502 that angled off to both sides of the germanium photodetector layer 16 . It is within the scope of the exemplary embodiments for the photodetector layer extensions 30 , 402 , 402 ′, 502 to angle off to only one side as is the case with the photodetector layer extensions 602 of the germanium photodetector 600 .
- photodetector layer extension 702 angles off to only one side of the germanium photodetector layer 16 as compared to germanium photodetector 500 where the photodetector layer extensions 502 angle off to both sides of the germanium photodetector layer 16 .
- germanium photodetector 800 is illustrated which is similar to germanium photodetector 10 except that germanium photodetector 800 has a wider portion 16 D of the photodetector layer 16 near the seed window 18 .
- the photodetector layer 16 may have a width 40 as indicated in FIG. 8 in the range of 0.5 to 3 ⁇ m, for example a width of 1.0 ⁇ m.
- the wider portion 16 D may have a maximum width 46 as indicated in FIGS. 8 of 1.5 to 5 times, for example 3 times, the width 40 of the photodetector layer 16 . It is noted that the wider portion 16 D gradually tapers from the seed window 18 to where the wider portion 16 meets the remaining photodetector layer 16 .
- germanium photodetector 800 An advantage of germanium photodetector 800 is that any defects during the recrystallization of the germanium are pushed further past the end 16 C of the germanium photodetector layer 16 into the photodetector layer extensions 30 . Another advantage of germanium photodetector 800 is that the wider portion 16 D of the photodetector layer 16 helps to increase the mole fraction of germanium in the photodetector diode 16 A.
- germanium photodetector 900 is illustrated which is similar to germanium photodetector 800 except that germanium photodetector 900 has a different wider portion 16 E of the photodetector layer 16 near the seed window 18 .
- the photodetector layer 16 may have a width 40 as indicated in FIG. 9 in the range of 0.5 to 3 ⁇ m, for example a width of 1.0 ⁇ m.
- the wider portion 16 E may have a maximum width 48 as indicated in FIGS. 9 of 1.5 to 5 times, for example 3 times, the width 40 of the photodetector layer 16 . It is noted that the wider portion 16 E of germanium photodetector 900 has a uniform width near the seed window and then gradually tapers to the main portion of the photodetector layer 16 .
- germanium photodetector 900 An advantage of germanium photodetector 900 is that any defects during the recrystallization of the germanium are pushed further past the end 16 C of the germanium photodetector layer 16 into the photodetector layer extensions 30 . Another advantage of germanium photodetector 900 is that the wider portion 16 D of the photodetector layer 16 helps to increase the mole fraction of germanium in the photodetector diode 16 A.
- germanium photodetector 1000 is illustrated which is similar to germanium photodetector 10 but differs in some respects. It is noted that germanium photodetector 1000 does not have the photodetector layer extensions previously described with respect to germanium photodetector 10 . It is further noted that the waveguide 12 having incoming light 14 of germanium photodetector 1000 angles underneath the photodetector layer 16 from the side and thereafter proceeds underneath the photodetector layer 16 past the seed window 18 . The waveguide 12 proceeds underneath the photodetector layer 16 at a point to the left of the end 16 C of the photodetector layer 16 .
- the distance between where the waveguide 12 angles underneath the photodetector layer 16 and the end 16 C of the photodetector layer 16 may be empirically determined as to be in the region 16 A where defects are minimized. This distance depends on the defect formation details of the process used to form the germanium photodetector 10 .
- germanium photodetector 1000 is that the defects are present at the end 16 C of the photodetector layer 16 and not in the portion of the photodetector layer 16 that comprises the photodetector diode 16 A. The result is that the photodetector diode 16 A is in the high responsivity and low defect region.
- germanium photodetector 1100 is illustrated which is similar to germanium photodetector 10 but differs in some respects. It is noted that germanium photodetector 1100 does not have the photodetector layer extensions previously described with respect to germanium photodetector 10 . It is further noted that the waveguide 12 having incoming light 14 of germanium photodetector 1000 angles underneath the photodetector layer 16 from the side and thereafter proceeds underneath the photodetector layer 16 . The path of the light from the waveguide 12 is from where the waveguide 12 angles underneath the photodetector layer 16 through the end 16 C of the photodetector layer 16 .
- the photodetector layer 16 recrystallizes from the waveguide 1102 and not waveguide 12 as in the previous embodiments.
- the photodetector diode 16 A is chosen at a location before the end 16 C so that the photodetector diode 16 A is at a high germanium mole fraction region but before the end 16 C of the photodetector layer 16 where defects might accumulate.
- the distance between the end 16 C and the location of the photodetector diode 16 A may be empirically determined as to be in the region 16 A where defects are minimized.
- germanium photodetector 1100 is that the defects are present at the end 16 C of the photodetector layer 16 and not in the photodetector diode 16 A. The result is that the photodetector diode 16 A is in the high responsivity and low defect region.
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- Optical Integrated Circuits (AREA)
Abstract
Photodetector including: a waveguide of a waveguide material extending over a substrate; an insulating layer formed over the waveguide and having an opening exposing the waveguide; a photodetector layer formed over the insulating layer and into the opening so as to make contact with the waveguide, the photodetector layer having a first end at the opening and a second end distal from the opening, the photodetector layer being a gradient material of the waveguide material and germanium wherein a waveguide material portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end; a photodetector region at the second end; and a photodetector layer extension extending at an angle from the photodetector layer at the second end.
Description
- The present exemplary embodiments pertain to optoelectronic devices and, more particularly, to waveguide photodetectors that convert optical signals into electrical signals.
- In optical communication systems, optical waveguides provide a transmission channel for guiding an optical signal produced by a light source, e.g., a laser, at one end of the system to a detector, e.g., a photodetector, at the other end of the system. The photodetector material, an active region, absorbs energy from the photons of the transmitted optical signal, which, in response, excites charge carriers, e.g., electrons and holes. With the application of a reverse bias voltage, the excited charge carriers are attracted to contacts on the photodetector, thereby creating an electrical current that corresponds to the optical signal. In this manner, the photodetector converts an optical signal into an electrical signal.
- Due to its potential for being grown on top of silicon, germanium is an appropriate choice for a photodetector.
- A lattice constant refers to the distance between unit cells in a crystal lattice. The lattice constant of germanium is not perfectly matched with the lattice constant of silicon; the lattice constant of germanium is slightly larger than that of silicon. The mismatch between the lattice constants of germanium and silicon presents problems for using a regular epitaxial growth (“EPI”) technique for growing crystals. Currently, two main methods have been heavily studied to make single crystal germanium film on top of silicon substrates. One method is using a buffer layer and post-process after selective epitaxial growth (“SEG”). The second method is using a rapid melt growth (“RMG”) technique. Between these two methods, RMG has better process compatibility but has a limitation on the structures that can be constructed.
- In the RMG technique, single crystal germanium is not grown directly on top of the silicon. Rather, poly-germanium or amorphous germanium is deposited on an insulator that has an opening (“seed window”) to an underlying silicon layer. An insulator, such as a nitride, is deposited to surround the poly-germanium or amorphous germanium. The RMG method requires a micro-crucible formed by the insulator surrounding the deposited poly-germanium or amorphous germanium which causes melting and recrystallization of the germanium when subjected to anneal.
- Optical detectors in a CMOS compatible process sequence can be accomplished inexpensively with an RMG germanium photodetector. RMG photodetectors have been built in silicon compatible processes but suffer from a couple of difficulties.
- One difficulty is that the silicon seed region contaminates the germanium photodetector resulting in a silicon germanium detector rather than a pure crystalline germanium photodetector. This can result in poor responsivity of the photodetector.
- Another difficulty is that the melting and subsequent recrystallization of the germanium photodetector can result in the formation of defects near the end of the photodetector affecting the yield and responsivity of the photodetector.
- The various advantages and purposes of the exemplary embodiments as described above and hereafter are achieved by providing, according to an aspect of the exemplary embodiments, a photodetector comprising: a waveguide extending over a substrate, the waveguide comprising a waveguide material; an insulating layer formed over the waveguide, the insulating layer having an opening exposing the waveguide; a photodetector layer formed over the insulating layer and into the opening so as to make contact with the waveguide, the photodetector layer having a first end at the opening and a second end distal from the opening, the photodetector layer being a gradient material of the waveguide material and germanium wherein a waveguide material portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end; a photodetector region at the second end; and a photodetector layer extension extends at an angle from the photodetector layer at the second end.
- According to another aspect of the exemplary embodiments, there is provided a photodetector comprising: a waveguide extending over a substrate, the waveguide comprising silicon; an insulating layer formed over the waveguide, the insulating layer having an opening exposing the waveguide; a linear photodetector layer formed over the insulating layer and into the opening so as to make contact with the waveguide, the linear photodetector layer having a first end at the opening and a second end at the terminus of the linear photodetector layer, the photodetector layer being a gradient material of the silicon and germanium wherein a silicon portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end; a photodetector at the terminus of the linear photodetector layer; and a photodetector layer extension extends at an angle from the terminus of the linear photodetector layer.
- According to a further aspect of the exemplary embodiments, there is provided a photodetector comprising: a waveguide extending over a substrate, the waveguide comprising silicon; an insulating layer formed over the waveguide, the insulating layer having an opening exposing the waveguide; a photodetector layer formed over the insulating layer and into the opening so as to make contact with the waveguide, the photodetector layer having a first end at the opening and a second end at a photodetector region formed in the photodetector layer, the photodetector layer being a gradient material of the silicon and germanium wherein a silicon portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end; a photodetector layer extension extends at an angle from the linear photodetector layer such that the photodetector layer and the photodetector layer extension are coplanar.
- According to another aspect of the exemplary embodiments, there is provided a photodetector comprising: a waveguide extending over a substrate, the waveguide has an incoming portion that joins with a main portion, the incoming portion being at an angle with respect to the main portion; an insulating layer formed over the waveguide, the insulating layer having an opening exposing the main portion of the waveguide; a photodetector layer formed over the insulating layer and into the opening so as to make contact with the main portion of the waveguide, the photodetector layer having a first end at the opening and a second end spaced from the first end, the photodetector layer being a gradient material of the silicon and germanium wherein a silicon portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end; the main portion of the waveguide extends underneath the photodetector layer from where the main portion of the waveguide joins with the incoming portion of the waveguide to and past the opening, the incoming portion juts outward from underneath the photodetector layer, an extension portion of the photodetector layer extends past where the main portion of the waveguide joins with the incoming portion of the waveguide to the second end; and a photodetector region formed in the photodetector layer that begins where the incoming portion of the waveguide joins with the main portion of the waveguide and extends towards the first end.
- According to yet another aspect of the exemplary embodiments, there is provided a photodetector comprising: a silicon waveguide extending over a substrate, the waveguide has an incoming portion that joins with a main portion, the incoming portion being at an angle with respect to the main portion; an insulating layer formed over the waveguide, the insulating layer having an opening exposing a silicon seed; a photodetector layer formed over the insulating layer and into the opening so as to make contact with the silicon seed, the photodetector layer having a first end at the opening and a second end spaced from the first end, the photodetector layer being a gradient material of the silicon and germanium wherein a silicon portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end; the main portion of the waveguide extends underneath the photodetector layer from where the main portion of the waveguide joins with the incoming portion of the waveguide to and past the second end, the incoming portion juts outward from underneath the photodetector layer, a portion of the photodetector layer extends past where the main portion of the waveguide joins with the incoming portion of the waveguide to the first end; and a photodetector region formed in the photodetector layer at the second end and over the main portion of the waveguide.
- The features of the exemplary embodiments believed to be novel and the elements characteristic of the exemplary embodiments are set forth with particularity in the appended claims. The Figures are for illustration purposes only and are not drawn to scale. The exemplary embodiments, both as to organization and method of operation, may best be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings in which:
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FIG. 1 is a plan view of an embodiment of a germanium photodetector. -
FIG. 2 is a cross sectional view of the germanium photodetector ofFIG. 1 in the direction of arrows 2-2. -
FIG. 3 is an enlarged plan view of a section of the germanium photodetector ofFIG. 1 circumscribed by the dashed rectangle inFIG. 1 . -
FIG. 4A is a plan view of another embodiment of a germanium photodetector andFIG. 4B is a plan view of a modified version of the germanium photodetector ofFIG. 4A . -
FIG. 5 is a plan view of another embodiment of a germanium photodetector. -
FIG. 6 is a plan view of another embodiment of a germanium photodetector. -
FIG. 7 is a plan view of another embodiment of a germanium photodetector. -
FIG. 8 is a plan view of another embodiment of a germanium photodetector. -
FIG. 9 is a plan view of another embodiment of a germanium photodetector. -
FIG. 10 is a plan view of another embodiment of a germanium photodetector -
FIG. 11 is a plan view of another embodiment of a germanium photodetector. - There are several advantages of the exemplary embodiments. One advantage is the creation of a photodetector with a silicon-rich region away from the incident light. Another advantage is a germanium-rich region near the incidence of the optical signal. A further advantage is a defect gettering region out of the path of the optical signal.
- Referring to the Figures in more detail, and particularly referring to
FIG. 1 , there is a plan view of an exemplary embodiment of agermanium photodetector 10. Thegermanium photodetector 10 includes awaveguide 12, usually silicon, with the incoming signal, indicated byarrow 14, as coming in to thegermanium photodetector 10 from the right. Thephotodetector layer 16 makes contact with theunderlying waveguide 12 throughseed window 18. The right side of thephotodetector layer 16, indicated bydashed oval 16A, contains a photodetector diode. Surrounding thephotodetector layer 16 is aninsulator 20, such as nitride. Surrounding thegermanium photodetector 10 may be an oxide (not shown). - The formation of the germanium photodetector 10 (or any of the subsequent embodiments) may be accomplished in a CMOS (Complementary Metal Oxide Semiconductor) manufacturing line. It has been found that the exemplary embodiments formed by a CMOS process minimize the difficulties of the prior art with respect to contamination of the germanium and the formation of defects.
- Referring now to
FIG. 2 , there is a cross sectional view ofgermanium photodetector 10 taken in the direction of arrows 2-2 inFIG. 1 . Thegermanium photodetector 10 may be formed on asemiconductor base 22, such as silicon, followed by a buriedoxide layer 24, thewaveguide 12, aninsulator layer 26, such as a nitride, thephotodetector layer 16 andinsulator 20. Thephotodetector layer 16 has aportion 28 which extends throughseed window 18 to contact thewaveguide 12. - The
germanium photodetector 10 may be formed by a process that includes forming thewaveguide 12 on the buriedoxide layer 24 followed by theinsulator 26. Theseed window 18 may be formed in theinsulator 26. Thereafter, poly-germanium or amorphous germanium may be deposited, including in theseed window 18, followed by patterning to form thephotodetector layer 16. For purposes of illustration and not limitation, thephotodetector layer 16 may have awidth 40 as indicated inFIG. 1 in the range of 1 to 5 μm, for example a width of 2.5 μm. Thegermanium photodetector layer 16 may be encapsulated with theinsulator 20 followed by heating to at least the melting point of germanium according to the RMG process. - As a result of the RMG process, a gradient of silicon germanium is formed. The mole fraction of silicon is highest at the
seed window 18 and gradually decreases to zero or near zero at thephotodetector diode 16A. Conversely, the mole fraction of germanium is lowest at the seed window and gradually increases to 100% or nearly 100% at thephotodetector diode 16A. Preferably, the mole fraction of germanium at theleft edge 16B of thephotodetector diode 16A should be at least 95%. - The
photodetector layer 16 further includes one or morephotodetector layer extensions 30. For purposes of illustration and not limitation, the photodetector layer extensions may have alength 42 indicated inFIGS. 1 of 1 to 10 μm, for example a length of 3 μm. An advantage of thephotodetector extensions 30 is that defects that may ordinarily form at theend 16C of thephotodetector layer 16 are now pushed into thephotodetector layer extensions 30. Thus, thephotodetector layer 16 withinphotodetector diode 16A is now free of these defects so that the yield and responsivity of thephotodetector diode 16A is improved. - Referring now to
FIG. 3 , thephotodetector diode 16A withinrectangle 21 ofFIG. 1 is shown in more detail. Oneportion 32 of thephotodetector diode 16A may be n doped andmetal contacts 34 formed while asecond portion 36 may be p doped andmetal contacts 38 formed. Theinsulator 20 may be optionally removed for doping of thephotodetector diode 16A after the RMG process to minimize doping implant energy. If theinsulator 20 remains in place, themetal contacts 34 may be formed by locally etching through theinsulator 20 and then depositing metal for themetal contacts 34. - Also shown in more detail are
photodetector layer extensions 30 which angle off to the side of thephotodetector layer 16. Thephotodetector layer extensions 30 are shown as being perpendicular tophotodetector layer 16 but lesser or greater angular extensions may also be formed. The dashed lines indicate where thephotodetector layer 16 ends and thephotodetector layer extensions 30 begin. - Referring now to
FIG. 4A , another exemplary embodiment of agermanium photodetector 400 is illustrated which is similar togermanium photodetector 10 except thatgermanium photodetector 400 has differentphotodetector layer extensions 402. Thephotodetector layer extensions 402 include photodetectorlayer extension portions 404 which angle off to the side ofphotodetector layer 16 and photodetectorlayer extension portions 406 which angle off to the side of photodetectorlayer extension portions 404. In one embodiment, photodetectorlayer extension portions 406 may be parallel tophotodetector layer 16. - Referring now to
FIG. 4B , thegermanium photodetector 400 has been modified, now germaniumphotodetector 400′, in that the photodetectorlayer extension portions 406 have been increased in length and now shown as photodetectorlayer extension portions 406′. - An advantage of
germanium photodetectors end 16C of thegermanium photodetector layer 16 into thephotodetector layer extensions 402. - Referring now to
FIG. 5 , another exemplary embodiment of agermanium photodetector 500 is illustrated which is similar togermanium photodetector 10 except thatgermanium photodetector 500 has differentphotodetector layer extensions 502. Thephotodetector layer extensions 502 include photodetectorlayer extension portions 504 which angle off to the side ofphotodetector layer 16 and photodetectorlayer extension portions 506 which angle off to the side of photodetectorlayer extension portions 504. In one embodiment, photodetectorlayer extension portions 506 may be parallel tophotodetector layer 16.Germanium photodetector 500 may include additionalphotodetector layer extensions 508 which may angle off to the side ofphotodetector layer extensions 506. - An advantage of
germanium photodetector 500 is that any defects during the recrystallization of the germanium are pushed further past theend 16C of thegermanium photodetector layer 16 into thephotodetector layer extensions 502. - Referring now to
FIG. 6 , another exemplary embodiment of agermanium photodetector 600 is illustrated which is similar togermanium photodetector 10 except thatgermanium photodetector 600 has a differentphotodetector layer extension 602. Thephotodetector layer extension 602 curves off to one side ofphotodetector layer 16. For purposes of illustration and not limitation, thephotodetector layer extension 602 may deviate to oneside 44 as indicated inFIG. 6 by 1 to 10 μm, for example 5 μm. - An advantage of
germanium photodetector 600 is that any defects during the recrystallization of the germanium are pushed further past theend 16C of thegermanium photodetector layer 16 into thephotodetector layer extensions 602. - The
previous germanium photodetectors photodetector layer extensions germanium photodetector layer 16. It is within the scope of the exemplary embodiments for thephotodetector layer extensions photodetector layer extensions 602 of thegermanium photodetector 600.Germanium photodetector 700 inFIG. 7 is one such example where thephotodetector layer extension 702 angles off to only one side of thegermanium photodetector layer 16 as compared togermanium photodetector 500 where thephotodetector layer extensions 502 angle off to both sides of thegermanium photodetector layer 16. - Referring now to
FIG. 8 , another exemplary embodiment of agermanium photodetector 800 is illustrated which is similar togermanium photodetector 10 except thatgermanium photodetector 800 has awider portion 16D of thephotodetector layer 16 near theseed window 18. For purposes of illustration and not limitation, thephotodetector layer 16 may have awidth 40 as indicated inFIG. 8 in the range of 0.5 to 3 μm, for example a width of 1.0 μm. Further, for purposes of illustration and not limitation, thewider portion 16D may have amaximum width 46 as indicated inFIGS. 8 of 1.5 to 5 times, for example 3 times, thewidth 40 of thephotodetector layer 16. It is noted that thewider portion 16D gradually tapers from theseed window 18 to where thewider portion 16 meets the remainingphotodetector layer 16. - An advantage of
germanium photodetector 800 is that any defects during the recrystallization of the germanium are pushed further past theend 16C of thegermanium photodetector layer 16 into thephotodetector layer extensions 30. Another advantage ofgermanium photodetector 800 is that thewider portion 16D of thephotodetector layer 16 helps to increase the mole fraction of germanium in thephotodetector diode 16A. - Referring now to
FIG. 9 , another exemplary embodiment of agermanium photodetector 900 is illustrated which is similar togermanium photodetector 800 except thatgermanium photodetector 900 has a differentwider portion 16E of thephotodetector layer 16 near theseed window 18. For purposes of illustration and not limitation, thephotodetector layer 16 may have awidth 40 as indicated inFIG. 9 in the range of 0.5 to 3 μm, for example a width of 1.0 μm. Further, for purposes of illustration and not limitation, thewider portion 16E may have amaximum width 48 as indicated inFIGS. 9 of 1.5 to 5 times, for example 3 times, thewidth 40 of thephotodetector layer 16. It is noted that thewider portion 16E ofgermanium photodetector 900 has a uniform width near the seed window and then gradually tapers to the main portion of thephotodetector layer 16. - An advantage of
germanium photodetector 900 is that any defects during the recrystallization of the germanium are pushed further past theend 16C of thegermanium photodetector layer 16 into thephotodetector layer extensions 30. Another advantage ofgermanium photodetector 900 is that thewider portion 16D of thephotodetector layer 16 helps to increase the mole fraction of germanium in thephotodetector diode 16A. - Referring now to
FIG. 10 , another exemplary embodiment of agermanium photodetector 1000 is illustrated which is similar togermanium photodetector 10 but differs in some respects. It is noted thatgermanium photodetector 1000 does not have the photodetector layer extensions previously described with respect togermanium photodetector 10. It is further noted that thewaveguide 12 havingincoming light 14 ofgermanium photodetector 1000 angles underneath thephotodetector layer 16 from the side and thereafter proceeds underneath thephotodetector layer 16 past theseed window 18. Thewaveguide 12 proceeds underneath thephotodetector layer 16 at a point to the left of theend 16C of thephotodetector layer 16. The distance between where thewaveguide 12 angles underneath thephotodetector layer 16 and theend 16C of thephotodetector layer 16 may be empirically determined as to be in theregion 16A where defects are minimized. This distance depends on the defect formation details of the process used to form thegermanium photodetector 10. - The advantage of
germanium photodetector 1000 is that the defects are present at theend 16C of thephotodetector layer 16 and not in the portion of thephotodetector layer 16 that comprises thephotodetector diode 16A. The result is that thephotodetector diode 16A is in the high responsivity and low defect region. - Referring now to
FIG. 11 , another exemplary embodiment of agermanium photodetector 1100 is illustrated which is similar togermanium photodetector 10 but differs in some respects. It is noted thatgermanium photodetector 1100 does not have the photodetector layer extensions previously described with respect togermanium photodetector 10. It is further noted that thewaveguide 12 havingincoming light 14 ofgermanium photodetector 1000 angles underneath thephotodetector layer 16 from the side and thereafter proceeds underneath thephotodetector layer 16. The path of the light from thewaveguide 12 is from where thewaveguide 12 angles underneath thephotodetector layer 16 through theend 16C of thephotodetector layer 16. The light from thewaveguide 12 never passes by theseed window 18. In this regard, thewaveguide 12 is decoupled from anotherwaveguide 1102 that is underneath theseed window 18. During the RMG process, thephotodetector layer 16 recrystallizes from thewaveguide 1102 and not waveguide 12 as in the previous embodiments. Further, thephotodetector diode 16A is chosen at a location before theend 16C so that thephotodetector diode 16A is at a high germanium mole fraction region but before theend 16C of thephotodetector layer 16 where defects might accumulate. The distance between theend 16C and the location of thephotodetector diode 16A may be empirically determined as to be in theregion 16A where defects are minimized. - The advantage of
germanium photodetector 1100 is that the defects are present at theend 16C of thephotodetector layer 16 and not in thephotodetector diode 16A. The result is that thephotodetector diode 16A is in the high responsivity and low defect region. - It will be apparent to those skilled in the art having regard to this disclosure that other modifications of the exemplary embodiments beyond those embodiments specifically described here may be made without departing from the spirit of the invention. Accordingly, such modifications are considered within the scope of the invention as limited solely by the appended claims.
Claims (25)
1. A photodetector comprising:
a waveguide extending over a substrate, the waveguide comprising a waveguide material;
an insulating layer formed over the waveguide, the insulating layer having an opening exposing the waveguide;
a photodetector layer formed over the insulating layer and into the opening so as to make contact with the waveguide, the photodetector layer having a first end at the opening and a second end distal from the opening, the photodetector layer being a gradient material of the waveguide material and germanium wherein a waveguide material portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end;
a photodetector region at the second end; and
a photodetector layer extension extends at an angle from the photodetector layer at the second end.
2. The photodetector of claim 1 wherein the photodetector layer extension does not contain any portion of the photodetector region.
3. The photodetector of claim 1 wherein the photodetector layer extension is L shaped.
4. The photodetector of claim 1 wherein the photodetector layer extension is curved.
5. The photodetector of claim 1 wherein the photodetector layer and the photodetector layer extension are coplanar.
6. The photodetector of claim 1 wherein the waveguide material comprises silicon.
7. The photodetector of claim 1 wherein the photodetector layer has a width at the first end that is wider than a width of the photodetector layer at the second end.
8. The photodetector of claim 1 wherein the photodetector layer extension extends at an angle from the photodetector layer in only one direction.
9. A photodetector comprising:
a waveguide extending over a substrate, the waveguide comprising silicon;
an insulating layer formed over the waveguide, the insulating layer having an opening exposing the waveguide;
a linear photodetector layer formed over the insulating layer and into the opening so as to make contact with the waveguide, the linear photodetector layer having a first end at the opening and a second end at the terminus of the linear photodetector layer, the photodetector layer being a gradient material of the silicon and germanium wherein a silicon portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end;
a photodetector at the terminus of the linear photodetector layer; and
a photodetector layer extension extends at an angle from the terminus of the linear photodetector layer.
10. The photodetector of claim 9 wherein the photodetector layer extension extends at an angle from the linear photodetector layer in only one direction.
11. The photodetector of claim 9 wherein the photodetector layer extension extends at an angle from the linear photodetector layer in two directions.
12. The photodetector of claim 9 wherein the photodetector layer extension comprises a portion parallel and spaced from the linear photodetector layer.
13. The photodetector of claim 9 wherein the photodetector layer extension is curved.
14. The photodetector of claim 9 wherein the photodetector layer and the photodetector layer extension are coplanar.
15. The photodetector of claim 9 wherein the photodetector layer has a width at the first end that is wider than a width of the photodetector layer at the second end.
16. A photodetector comprising:
a waveguide extending over a substrate, the waveguide comprising silicon;
an insulating layer formed over the waveguide, the insulating layer having an opening exposing the waveguide;
a photodetector layer formed over the insulating layer and into the opening so as to make contact with the waveguide, the photodetector layer having a first end at the opening and a second end at a photodetector region formed in the photodetector layer, the photodetector layer being a gradient material of the silicon and germanium wherein a silicon portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end;
a photodetector layer extension extends at an angle from the photodetector layer such that the photodetector layer and the photodetector layer extension are coplanar.
17. The photodetector of claim 16 wherein the photodetector layer extension does not contain any portion of the photodetector region.
18. The photodetector of claim 16 wherein the photodetector layer extension extends at an angle from the linear photodetector layer in only one direction.
19. The photodetector of claim 16 wherein the photodetector layer extension extends at an angle from the linear photodetector layer in two directions.
20. The photodetector of claim 16 wherein the photodetector layer extension comprises a portion parallel and spaced from the linear photodetector layer.
21. The photodetector of claim 16 wherein the photodetector layer has a width at the first end that is wider than a width of the photodetector layer at the second end.
22. A photodetector comprising:
a waveguide extending over a substrate, the waveguide has an incoming portion that joins with a main portion, the incoming portion being at an angle with respect to the main portion;
an insulating layer formed over the waveguide, the insulating layer having an opening exposing the main portion of the waveguide;
a photodetector layer formed over the insulating layer and into the opening so as to make contact with the main portion of the waveguide, the photodetector layer having a first end at the opening and a second end spaced from the first end, the photodetector layer being a gradient material of the silicon and germanium wherein a silicon portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end;
the main portion of the waveguide extends underneath the photodetector layer from where the main portion of the waveguide joins with the incoming portion of the waveguide to and past the opening, the incoming portion juts outward from underneath the photodetector layer, an extension portion of the photodetector layer extends past where the main portion of the waveguide joins with the incoming portion of the waveguide to the second end; and
a photodetector region formed in the photodetector layer that begins where the incoming portion of the waveguide joins with the main portion of the waveguide and extends towards the first end.
23. The photodetector of claim 22 wherein the extension portion of the photodetector layer does not contain any portion of the photodetector.
24. A photodetector comprising:
a silicon waveguide extending over a substrate, the waveguide has an incoming portion that joins with a main portion, the incoming portion being at an angle with respect to the main portion;
an insulating layer formed over the waveguide, the insulating layer having an opening exposing a silicon seed;
a photodetector layer formed over the insulating layer and into the opening so as to make contact with the silicon seed, the photodetector layer having a first end at the opening and a second end spaced from the first end, the photodetector layer being a gradient material of the silicon and germanium wherein a silicon portion of the gradient material varies from a maximum at the first end to a minimum at the second end and wherein a germanium portion of the gradient material varies from a minimum at the first end to a maximum at the second end;
the main portion of the waveguide extends underneath the photodetector layer from where the main portion of the waveguide joins with the incoming portion of the waveguide to and past the second end, the incoming portion juts outward from underneath the photodetector layer, a portion of the photodetector layer extends past where the main portion of the waveguide joins with the incoming portion of the waveguide to the first end; and
a photodetector region formed in the photodetector layer at the second end and over the main portion of the waveguide.
25. The photodetector of claim 24 wherein the silicon seed is decoupled from the waveguide.
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US15/486,810 US10103280B1 (en) | 2017-04-13 | 2017-04-13 | Rapid melt growth photodetector |
CN201880023166.1A CN110462848B (en) | 2017-04-13 | 2018-04-10 | Photoelectric detector for quick melt growth |
GB1915262.8A GB2575750B (en) | 2017-04-13 | 2018-04-10 | Rapid melt growth photodetector |
PCT/IB2018/052487 WO2018189666A1 (en) | 2017-04-13 | 2018-04-10 | Rapid melt growth photodetector |
JP2019552454A JP7128200B2 (en) | 2017-04-13 | 2018-04-10 | Rapid melt growth photodetector |
DE112018000637.9T DE112018000637T5 (en) | 2017-04-13 | 2018-04-10 | Photodetector made by growth after rapid melting |
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US15/486,810 US10103280B1 (en) | 2017-04-13 | 2017-04-13 | Rapid melt growth photodetector |
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US10103280B1 US10103280B1 (en) | 2018-10-16 |
US20180301568A1 true US20180301568A1 (en) | 2018-10-18 |
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JP4267266B2 (en) | 2001-07-10 | 2009-05-27 | 株式会社半導体エネルギー研究所 | Method for manufacturing semiconductor device |
US7122392B2 (en) | 2003-06-30 | 2006-10-17 | Intel Corporation | Methods of forming a high germanium concentration silicon germanium alloy by epitaxial lateral overgrowth and structures formed thereby |
US7603016B1 (en) * | 2007-04-30 | 2009-10-13 | The United States Of America As Represented By The Secretary Of The Air Force | Semiconductor photonic nano communication link apparatus |
US8343792B2 (en) | 2007-10-25 | 2013-01-01 | Bae Systems Information And Electronic Systems Integration Inc. | Method for manufacturing lateral germanium detectors |
US7902620B2 (en) | 2008-08-14 | 2011-03-08 | International Business Machines Corporation | Suspended germanium photodetector for silicon waveguide |
US8304272B2 (en) | 2010-07-02 | 2012-11-06 | International Business Machines Corporation | Germanium photodetector |
WO2012008272A1 (en) * | 2010-07-16 | 2012-01-19 | 日本電気株式会社 | Light-receiving element, optical communication device equipped with same, process for production of light-receiving element, and process for production of optical communication device |
US8633067B2 (en) * | 2010-11-22 | 2014-01-21 | International Business Machines Corporation | Fabricating photonics devices fully integrated into a CMOS manufacturing process |
CN102569513B (en) * | 2010-12-22 | 2016-02-17 | 李冰 | A kind of Waveguide optical detector and preparation method thereof |
US9229164B2 (en) * | 2013-04-23 | 2016-01-05 | Globalfoundries Inc. | Butt-coupled buried waveguide photodetector |
US9224882B2 (en) | 2013-08-02 | 2015-12-29 | Intel Corporation | Low voltage photodetectors |
US9171971B2 (en) | 2013-10-31 | 2015-10-27 | Globalfoundries U.S. 2 Llc | Encapsulated sensors |
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US9466753B1 (en) * | 2015-08-27 | 2016-10-11 | Globalfoundries Inc. | Photodetector methods and photodetector structures |
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US10103280B1 (en) | 2018-10-16 |
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