Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Information Disclosure Statement
The information disclosure statements (IDS) submitted on 11/18/2024 and 4/16/2025 are in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statements are being considered by the examiner.
Claim Objections
Claims 1-12, are objected to because of the following informalities: the “carrier generating region comprising a semiconductor having a bandgap that absorbs light of a given wavelength.” In addition, the bandgap of “an n-doped semiconductor region and a p-doped semiconductor region having respective band gaps . . .” is later introduced. The bandgap of the carrier generating region being referred to as “the bandgap” and the bandgaps of the p-doped or n-doped regions being referred to as “the respective bandgaps” is unclear, as it is difficult to determine which bandgap(s) are being referred to. For example, the bandgap of the carrier region could be referred to as a “first bandgap” and the bandgaps of the p-doped and n-doped regions could be referred to as “second and third bandgaps” for clarity; when referring to either the p-doped or n-doped bandgaps, language similar to “the second or third bandgaps” can be utilized. Similar language appears in claims 2-12. Appropriate correction is required.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claim(s) 1, 3-5, and 8-12 is/are rejected under 35 U.S.C. 103 as being unpatentable over Chern (US 20210091246 A1).
Regarding claim 1, Chern teaches, in 1A, a photodiode comprising a carrier generating region (formed by “light absorption material” 132) having a bandgap that absorbs light of a given wavelength such that electrical charge carriers are generated in the carrier generating region by the light of the given wavelength.
[0020] states “In some embodiments, the semiconductor layer 107 is made of silicon, such as intrinsic silicon” and [0021] states “The semiconductor layer 107 is globally doped with a first conductive type dopant (such as an n-type dopant) . . . thereby forming a doped semiconductor layer 108, meaning that the n-type layer is made of silicon. Similarly, [0052] states “In some embodiments, the second electrode region 148 made of silicon (Si) . . . The second electrode region 148 is in-situ doped with a second conductive type dopant (such as a p-type dopant) . . .” [0039] additionally states “In some embodiments, the light absorption material 132 is intrinsic germanium.” The examiner notes that doped silicon has a higher bandgap than that of intrinsic germanium; therefore, the n-doped semiconductor region 108 and p-doped semiconductor region 148 have respective bandgaps higher than the bandgap of the carrier generating region.
Further, the n-doped semiconductor region and the p-doped semiconductor region are along different sides of the carrier generating region (see FIG. 1V); and an interface region between the carrier generating region and a given doped region of the n-doped semiconductor region (“lower superlattice structure” 126) or the p-doped semiconductor region (“upper superlattice structure” 142), the interface region comprising one or more of a semiconductor alloy and a semiconductor sequence that is stepped in composition (see FIG. 1O-1), selected to reduce a band offset between the carrier generating region and the given doped region adjacent the interface region (as [0062 states: “Furthermore, the first superlattice structure 126 includes the silicon germanium layer 130 having the atomic percentage of germanium increasing in order as the level of the silicon germanium layer 130 increase, lattice mismatch between the light absorption material 132 and the semiconductor layer 108 may be further mitigated or eliminated. Similarly, the second superlattice structure 142 includes the silicon germanium layer 146 having the atomic percentage of germanium decreasing in order as the level of the silicon germanium layer 146 increases”). The examiner notes that this inherently reduces a band offset between the germanium carrier region and the doped region adjacent to the interface region. Further, in [0016]: Chern suggests the use of a silicon waveguide: “Wavelengths of 1310 nm and 1550 nm generally are applied in data-communication and telecommunication, respectively . . .a silicon waveguide is able to confine and connect infrared light (wavelength greater than about 700 nm) due to its strong refractive index (about 3.47).” The examiner notes that this indicates that silicon is able to be translucent at wavelengths greater than 700 nm.
However, Chern does not explicitly teach that the respective bandgaps (of the p-doped and n-doped regions) are transparent to the light of the given wavelength.
It would have been obvious to one having ordinary skill in the art at the effective filing date to select a given wavelength for the carrier region taught by Chern such that the n-doped and p-doped regions are translucent to the given wavelength that the carrier region absorbs. One having ordinary skill in the art is motivated to do so because, for example, Chern teaches that “Wavelengths of 1310 nm and 1550 nm generally are applied in data-communication and telecommunication, respectively” (also note that silicon is translucent to “wavelengths greater than 700 nm”, see above), and choosing one of these wavelengths allows for the device to be used alongside other devices in the art (utilizing these wavelengths), increase economic viability. See KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007).
Regarding claim 3, as explained above, Chern teaches that the carrier generating region comprises the carrier generating semiconductor germanium, and that the doped (n-doped and p-doped) transparent regions (see above) comprises silicon, which is different than germanium. Chern further teaches that the content of germanium (the carrier-generating semiconductor) decreases from the carrier generating region to the given doped region (p-type and n-type regions) via the interface regions (see above). The examiner notes that because the percentage of germanium decreases in this silicon-germanium layer, the percentage of silicon increases along the same direction, to fill in the material no longer made of germanium. Also see FIG. 1O-1
Regarding claim 4, as explained above, Chern teaches that the carrier generating region comprises the carrier generating semiconductor germanium, and that the doped (n-doped and p-doped) transparent regions (see above) comprises silicon, which is different than germanium. In, the decreasing germanium content (the carrier-generating semiconductor) in the interface has at least one step in content, with a similar step in silicon (transparent semiconductor) to take the place of the germanium content.
Regarding claim 5, as explained (directly) above, the interface region (126 or 142) has at least one step in germanium-to silicon content; therefore, the interface provides one or more band offset steps in the band offset between the carrier generating region and the given doped region (108 or 148, respectively), as the change in germanium-to-silicon ratios in the steps inherently provides offset steps.
Regarding claim 8, as explained above, Chern teaches that the semiconductor of the carrier generating region is (carrier-generating) germanium. Further, the semiconductor has a given doped region comprising a p-doped silicon semiconductor region (see above).
Regarding claims 9 and 10, Chern further teaches, in [0060]: “Once light absorption material 132 absorbs a light signal and generates an electron-hole pair, hole passes through the first superlattice structure 126 and the semiconductor layer 108 . . .” Once light absorption material 132 absorbs a light signal and generates an electron-hole pair, hole passes through the first superlattice structure 126 and the semiconductor layer 108 to be swept to the first electrode regions 114 (cathode) while the electron passes through the second superlattice structure 142 to be swept to the second electrode region 148 (anode).” The examiner notes that conduction bands are reduced for these carriers by the interface regions 126 and 142 (see above).
Regarding claim 11, as explained above, the n-doped semiconductor region and the p- doped semiconductor region are on opposite sides of the carrier generating region, with the interface region between the carrier generating region and one of the n-doped semiconductor region (see interface region 126 above).
Regarding claim 12, Chern further teaches, in FIG. 1V, that the n-doped semiconductor region 108 and the p-doped semiconductor region are on adjacent sides of the carrier generating region 132, with the interface region 126 being between the carrier generating region and the n-doped semiconductor region.
Claim(s) 2 is/are rejected under 35 U.S.C. 103 as being unpatentable over Chern (US 20210091246 A1) in view of Morse (US 20100327381 A1).
Regarding claim 2, as explained above, Chern teaches the limitations of claim 1 and that the carrier generating region comprises the carrier generating semiconductor germanium, and that the doped (n-doped and p-doped) transparent regions (see above) comprises silicon, which is different than germanium. Chern further teaches that the content of germanium (the carrier-generating semiconductor) decreases from the carrier generating region to the given doped region (p-type and n-type regions) via the interface regions (see above). The examiner notes that because the percentage of germanium decreases in this silicon-germanium layer, the percentage of silicon increases along the same direction, to fill in the material no longer made of germanium.
Chern does not teach a graded alloy of the carrier-generated semiconductor in the interface region.
Morse teaches, in abstract, an “i-layer tuned to absorb a first wavelength,” FIG. 1 shows a photodiode comprising the i-layer 120A, and [0020] further teaches “In further embodiments, an interface layer (not depicted) may be disposed between the i-layer 120A and either of the doped layer 110A and the complementarily doped layer 130A. The interface layer may be a graded layer, linear or otherwise, to transition the semiconductor film composition from the i-layer 120A to either or both of the doped or complementarily doped layer. For example, where the i-layer 120A is at least 80 at. % germanium and a p-type layer and an n-type layer are substantially silicon (i.e., no more than 40 at. % Ge), an intervening interface layer may grade the Si--Ge composition from that of the doped/complementarily doped layers to that of the i-layer.” The examiner notes that, in this case, the semiconductor graded alloy is a silicon-germanium alloy, carrier-generating semiconductor is germanium and the given doped region comprises silicon.
It would have been obvious to one having ordinary skill in the art at the effective filing date to modify the device taught by Chern such that the interface region is graded, as taught by Morse. One having ordinary skill in the art is motivated to do so because, for example, Chern teaches “the superlattice structures may reduce the band-gap offset between silicon and germanium, which may improve the performance of the photodetector, e.g., responsivity” and one of ordinary skill in the art appreciates that a graded interface layer achieves the same effect (i. e., reducing the band-gap offset between silicon and germanium).
Claim(s) 6-7 is/are rejected under 35 U.S.C. 103 as being unpatentable over Chern (US 20210091246 A1) in view of Yagi (US 20130001643 A1).
Regarding claim 6, as explained above, Chern teaches the limitations of claim 1. Chern does not teach that the interface region is formed of a portion of the carrier generating region closest to the given doped region.
Yagi teaches, in FIG. 1, a photodiode comprising a stack of semiconductor layers, [0032] states: “As shown in FIG. 1, the process sequentially grows, on the primary surface 1S of the substrate 1, . . . a lower contact layer 5, a first intermediate layer 7, a second intermediate layer 9, an absorption layer 11, a third intermediate layer 13, a fourth intermediate layer 15, . . . and an upper contact layer 19 in this order” and [0033] states: “The first and second intermediate layers, 7 and 9, where they are put between the lower contact layer 5 and the absorption layer 11, may be made of i-GaInAsP.” The absorption layer 11 may be made of the same (see top of [0034]). Yagi further teaches, in FIG. 2 and [0038], “Because of the existence of the first and second intermediate layers, 7 and 9, the bottom of the conduction band rises in stepwise from the absorption layer 11 to the lower contact layer 5. On the other hand, the first and second intermediate layers, 7 and 9, may fall the top of the valence band in stepwise from the absorption layer 11 to the lower contact layer 5.” The examiner notes that the intermediate layers 7 and 9 therefore make up an interface region. Further, FIG. 3 shows “stack” 23 and [0035] states: “ Thus, the stack 23 may be made by the group III-V compound semiconductor materials and contains a p-i-n structure (hereafter denoted as pin) 21 for the pin-PD. In the present embodiment shown in FIG. 1, the lower contact layer 5 operates as the p-type layer of a pin-PD, the first and second intermediate layers, 7 and 9, and the absorption layer 11 constitute the i-type layer 12 of a pin-PD.” The examiner notes that this means that the interface region (7, 9) is formed from a portion of the carrier region is formed from a portion of the carrier generating region closes to the given doped region (in this case, the lower layer 5, doped with As and P).
It would have been obvious to one having ordinary skill in the art at the effective filing date to modify the device taught by Chern such that the interface region is formed from a portion of the carrier generating region closes to the given doped region. One having ordinary skill in the art is motivated to do so because, for example, the formation both structures at once reduces manufacturing steps, reducing production cost. See KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007).
Regarding claim 7, as shown (directly) above, Yagi teaches “a third intermediate layer 13, a fourth intermediate layer 15, . . . and an upper contact layer 19 [formed] in this order” on top of a carrier generating region (11, see above). The examiner notes that FIG. 2 further shows a step-wise conduction band from the carrier generating region to the upper contact layer 19 caused by the intermediate layers 13 and 15 (meaning that 13 and 15 make up an interface region). [0034] further states: “The absorption layer 11 may be made of i-GaInAs. The third and fourth intermediate layers, 13 and 15, where they are put between the absorption layer 11 and the cladding layer 17, may be made of n-type GaInAsP. The cladding layer 17 may be made of n-type InP, while the upper contact layer 19 may be made of n-type GaInAs.” The examiner notes that this teaches that the interface layer (13, 15) is formed from a portion of the given doped region closes to the carrier generating region (11, see FIG. 1).
It would have been obvious to one having ordinary skill in the art at the effective filing date to modify the device taught by Chern such that the interface region is formed from a portion of the carrier generating region closest to the given doped region, as taught by Yagi. One having ordinary skill in the art is motivated to do so because, for example, the formation both structures at once reduces manufacturing steps, reducing production cost. See KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure:
Vu (US 20150028286 A1) – FIG. 1 shows a photodiode with alternating Si-Ge layers around intrinsic germanium barriers, with n and p doped germanium diodes at alternate sides of the diode.
Verma (US 9213137 B2) – FIG. 9 shows a germanium light absorption layer in a photodiode with SOI waveguides.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to GABRIEL S MINNEY whose telephone number is (571)272-9688. The examiner can normally be reached Monday Friday, 8:30 a.m. 5 p.m. ET..
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Jacob Choi can be reached at (469) 295-9060. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/G.S.M./ Examiner, Art Unit 2897
/JACOB Y CHOI/ Supervisory Patent Examiner, Art Unit 2897
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