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 .
Allowable Subject Matter
Claims 192-196,199-201, 208-211 allowed.
The following is a statement of reasons for the indication of allowable subject matter:
See previously indicated allowable subject matter, see Applicant arguments filed 8/27/2025.
Note: The Examiner notes that the term “buffer layer” is very broad and includes doped layers under broadest reasonable interpreation, for example see Deligianni et al. (US 20190232083 A1) see paragraph 0027 “A highly n-doped buffer layer 304 is formed on the substrate 302 and may include, for example gallium nitride with a thickness between about 20 nm and about 1,000 nm. The Highly n-doped buffer layer 304 may act as a lower electrical contact for the device. An n-type semiconductor layer 306 is then formed on the buffer layer 304 with a lower dopant concentration than that used in the highly doped buffer layer 304 and with a thickness between about 100 nm and about 1,000 nm”, see for example that Deligianni differentiates the layer above it as having a “lower dopant concentration”, the Examiner notes that claim language has to be clear and there needs to be a way to differentiate layers from each other. The Examiner notes that if there is no support in the specification for clarifying the claims, then the Examiner cannot allow new matter to be used as a support for clarifying the claims or for obtaining allowance.
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claim(s) 190, 191, 203-207 is/are rejected under 35 U.S.C. 103 as being unpatentable over Stange et al. (see PTO-892 filed 11/6/2025 Stange et al. "High Sn‐Content GeSn Light Emitters for Silicon Photonics,") hereafter referred to as Stange in view of Prineas et al. (US 20200006592 A1) hereafter referred to as Prineas. LaChapelle et al. (US 20180284274 A1) hereafter referred to as LaChapelle is provided as evidence.
In regard to claim 190 Stange teaches a light-emitting diode [see Fig. 3 , see page 185], comprising:
a silicon-based [see Fig. 3 marked as Si(100)] substrate;
a heterostructure [see the p-i-n GeSn LED] at least partially extending over the silicon-based substrate, the heterostructure comprising a stack [see the p-i-n layers] of coextending [see the top part of P doped layer at the bottom shares a common sidewall with the layers above, so coextending limitation is satisfied at that point] layers, the stack of coextending layers comprising buffer layers [the p and n can be called as “buffer layers”, the Applicant can narrow the definition of buffer based on the specification] and a photoactive [see the undoped “i” layer] layer, each coextending layer comprising at least two [Ge, Sn] group IV elements and being configured for emitting [see “Power-dependent measurements at room temperature show the suitability of these group IV alloys as light emitters at low current densities of 55A/cm2 (see Fig. 4(c))”, the Examiner notes that a range of emission from 0.4eV to 0.6eV is shown i.e. 2.066 μm (i.e. short-wave) to 3.099 μm (i.e. mid-wave), see LaChapelle as evidence, see paragraph 0132 “near infrared ranges (NIR, 750-1000 nm), short-wave infrared ranges (SWIR, 1-2.5 μm), mid-wave infrared ranges (MWIR, 3-5 μm), or long-wave infrared ranges (LWIR, 8-12 μm)”] short-wave infrared and mid-wave infrared radiation, the short-wave infrared and mid-wave infrared radiation comprising some wavelengths in a wavelength range extending from about 1 μm to about 8 μm, depending on a relative concentration [see Ge is 0.89 Sn is 0.11] of said at least two group IV elements and a corresponding strain [“The LEDs presented here are p–i–n structures based on GeSn. They contain a Sn concentration of about 11.5% with a residual strain of −0.8%”] of each layer of the stack of coextending layers; and
electrodes [see the metal contacts in Fig. 3] operatively connected to the heterostructure,
but Stange does not show a plurality of photoactive layers however under broadest reasonable interpretation, since the claim does not state that the photoactive layers are different, they can be the upper and lower portions of the undoped “i” layer of Stange, thus a secondary reference is not required, the claim can be narrowed to require the photoactive layers be different.
However, the Examiner provides a secondary reference, see Stange “It is, however, obvious that GeSn p–i–n homojunction LEDs do not provide a good confinement of carriers inside the active region (when targeting optimized LED structures and designing electrically pumped lasers). Also, heterostructures likeGe/GeSn/Ge do not offer high band offsets. The Ge layer sitting on top of the thick, nearly fully relaxed GeSn layer, is necessarily under tensile strain, making type I band alignment difficult to reach. Therefore, it seems mandatory to use SiGeSn as a cladding material. In addition, multiquantum well (MQW) structures may offer low threshold powers given their 2D density of states” see also “Another approach consists in growing GeSn layers with high amounts of tin. This reduces the energy separation between conduction band valleys and the valence band as Sn content increases, with a stronger effect for the Γ-valley than for the L-valley,8–10 leading to a transition from an indirect to a direct bandgap for sufficiently high Sn content. The transition point for unstrained GeSn compounds was calculated to occur at a Sn concentration between 5% and 12%”, thus the concentration in the example of Fig. 3 is only one example.
See Prineas teaches , see Fig. 2, see Abstract “Methods and a device for cascading broadband emission are described. An example device can comprise a substrate, a bottom contact layer above at least a portion of the substrate, and a plurality of emission regions above the bottom contact layer. The plurality of emission regions can be disposed one above another. Each of the plurality of emission regions can be configured with different respective band gaps to emit radiation of different wavelengths. The device can comprise a plurality of tunnel junctions. Each of the tunnel junctions can be disposed between at least two corresponding emission regions of the plurality of emission regions. The device can comprise a top contact layer above the plurality of emission regions”, see Fig. 2, see paragraph 0033, 0042 “the tunnel junction used for such device may differ from the one disclosed herein, but can be one known by those of ordinary skill in the art” “tunnel junctions for the materials can be chosen to be wider gap than the emission regions to provide blocking layers to prevent electron/hole leakage between the emission regions prior to radiative recombination”.
See that the “tunnel junctions” of Prineas has similarity to “mandatory to use SiGeSn as a cladding material” of Stange i.e. SiGeSn is a buffer/cladding layer.
Thus, it 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 to modify Stange to include a plurality of photoactive layers of differing Sn concentration, with SiGeSn cladding which are stacked.
Thus it would be obvious to combine the references to arrive at the claimed invention.
The motivation is to obtain a broader emission spectrum than is possible with only a single photoactive layer.
In regard to claim 191 Stange and Prineas as combined teaches wherein said at least two group IV elements are selected [see Stange, see combination Prineas , see GeSn as light emitting layer and SiGeSn as cladding] from the group consisting of: Si, Ge and Sn.
In regard to claim 203 Stange and Prineas as combined teaches wherein the stack of coextending photoactive layers comprises [see Stange, see combination Prineas , see GeSn as light emitting layer and SiGeSn as cladding] at least one GeSn-based layer.
In regard to claim 204 Stange and Prineas as combined teaches wherein the stack of coextending photoactive layers comprises at least two GeSn-based layers [see Stange, see combination Prineas , see plurality of GeSn as light emitting layer of differing Sn concentration and SiGeSn as cladding, see Stange “transition point for unstrained GeSn compounds was calculated to occur at a Sn concentration between 5% and 12%”, see Fig. 3 uses strain, see “The LEDs presented here are p–i–n structures based on GeSn. They contain a Sn concentration of about 11.5% with a residual strain of −0.8%”], each of said at least two GeSn-based layers having a different chemical composition one from another, the different chemical composition comprising an Sn content, the Sn content being comprised in a range extending between 1 at% and 25 at%, each of said at least two GeSn-based layers having a different lattice strain one from another.
In regard to claim 205 Stange and Prineas as combined teaches further comprising a Ge-based virtual substrate [see Stange Fig. 3 see Ge-VS] extending over the silicon-based substrate.
In regard to claim 206 Stange and Prineas as combined teaches wherein the light-emitting diode is operable [see Stange Fig. 2, Fig. 4 see temperature] at room temperature.
In regard to claim 207 Stange and Prineas as combined teaches wherein the light-emitting diode is operable at a cryogenic temperature [see Stange Fig. 2, Fig. 4 see temperature], the cryogenic temperature being equal or greater than about 77 K.
Response to Arguments
Applicant's arguments filed 5/6/2026 have been fully considered but they are not persuasive.
On page 7, 8 the Applicant argues “Independent claim 190 as claimed is not directed merely to any GeSn p-i-n LED emitting somewhere in the infrared. Rather, independent claim 190, as claimed, claims a "light-emitting diode" including a "heterostructure" disposed over a "silicon-based substrate," the heterostructure including "a stack of coextending layers" comprising "buffer layers and photoactive layers," wherein each coextending layer comprises "at least two Group IV elements" and is configured to emit "short-wave infrared and mid-wave infrared7 of radiation" comprising wavelengths in a "range extending from about 1 pim to about 8 pim depending on a relative concentration of said at least two group IV elements and a corresponding strain of each layer of the stack of coextending layers." In particular, independent claim 190 expressly recites layer-by-layer Group IV composition and strain engineering as the mechanism by which the stack is configured for the claimed short-wave infrared and mid-wave infrared emission. Stange does not provide any such teaching. Stange describes a particular GeSn p-i- n LED structure having about 11.5% Sn and a residual strain of -0.8%. The electroluminescence demonstrated in Stange is confined to a limited mid-infrared band, which the Office Action identifies as about 0.40 eV to 0.60 eV, corresponding to approximately 2.066 pim to 3.099 pim. That disclosure does not teach a coextending stack of buffer layers and photoactive layers in which each layer comprises at least two Group IV elements and is configured so that emitted wavelengths over the claimed range depend on the relative Group IV concentration and corresponding strain of that layer. A single demonstrated GeSn p-i-n LED having one Sn content and one residual strain does not teach suggest or disclose the claimed composition/strain-selectable coextending stack”.
The Examiner responds that as noted in the rejection, the claim language is broad and currently it it is impossible to determine any infringement of the claims because there is no way to distinguish composition of layers from each other and there is only one wavelength range specified, thus the claim does not state that the photoactive layers are different, however, the Examiner has still provided a secondary reference teaching “cascading broadband emission” for the purpose of compact prosecution however under broadest reasonable interpretation the claim language is satisfied with or without the secondary reference . The Examiner notes that if there is no support in the specification for clarifying the claims, then the Examiner cannot allow new matter to be used as a support for clarifying the claims or for obtaining allowance.
On page 7-9 the Applicant argues “The rejection appears to treat p-type and n-type regions of Stange as buffer layers. Stange does not disclose that those regions are buffer layers within the claimed stack, nor that each such alleged buffer layer comprises at least two Group IV elements and has the claimed emission configuration based on its own relative Group IV concentration and corresponding strain. Merely relabeling p-type and n-type regions as "buffer layers" does not supply the missing structural and functional limitations of independent claim 190, as claimed. An arbitrary subdivision of one intrinsic region into upper and lower portions does not create distinct layers in a stack, nor does it provide separate layer-specific composition and strain characteristics. As such, the Office's reading of claim 190 is broader thanreasonable, because the Office's interpretation reads "layers "stack," and "each coextending layer" out of the claim. Additionally, the possible SiGeSn cladding for carrier confinement discussed in Stange does not cure the deficiencies. A suggestion to add a different cladding material for confinement is not a teaching of the claimed coextending buffer-layer/photoactive-layer stack in which each layer comprises at least two Group IV elements and is configured for SWIR/MWIR emission depending on relative Group IV concentration and corresponding strain. The claimed subject-matter addresses a different materials-engineering problem: controlling the optoelectronic behavior of Group IV heterostructures through coordinated composition and strain engineering of the coextending layers. The description supports this distinction by explaining that independently engineering Sn content and lattice strain enables relatively precise control of the optoelectronic properties of GeSn heterostructures, and that efficient direct band gap emission in these emerging semiconductors can be achieved at a Sn content around 10 at.% in fully relaxed layers . Applicant submits that Prineas is not analogous art for the purpose relied upon by the Office because Prineas is neither in the same field of endeavor nor reasonably pertinent to the problem addressed by the claimed subject-matter. Prineas describes cascaded broadband emission using III-V emission regions and tunnel-junction structures, including InAs/GaSb-type superlattices and related III-V material systems. That disclosure is not in the same field as the claimed silicon-compatible Group IV Ge/Si/Sn heterostructures, and it is not reasonably pertinent to the specific problem addressed by independent claim 190, which is to configure Group IV coextending buffer and photoactive layers so that SWIR/MWIR emission depends on relative Group IV concentration and corresponding strain of each layer. Even if Prineas were considered analogous prior art, Prineas fails to cure Stange's deficiencies. At most, Prineas describes multiple emission regions having different band gaps, but it does so in the context of cascaded III-V structures, not GeSn-on-silicon layer stacks. Prineas therefore does not teach or suggest a stack in which each coextending layer comprises at least two Group IV elements and is configured to emit wavelengths in the claimed range depending on relative Group IV concentration and corresponding strain. The Office Action uses Prineas for the general idea of multiple emission regions, while overlooking the specific Group IV composition/strain mechanism as claimed in independent claim 190.
The Examiner responds that simply calling a layer a buffer layer in claim language does not not give it a composition and simply means that it is the lower portion of some layer under broadest reasonable interpretation, thus the Applicant can clarify the claims to specify composition or doping type and/or concentration etc, in order to distinguish from the prior art, however just using a term “buffer layer” does not make the claim allowable. The Examiner responds that as noted in the rejection, the claim language is broad and currently it it is impossible to determine any infringement of the claims because there is no way to distinguish composition of layers from each other and there is only one wavelength range specified, thus the claim does not state that the photoactive layers are different, however, the Examiner has still provided a secondary reference teaching “cascading broadband emission” for the purpose of compact prosecution however under broadest reasonable interpretation the claim language is satisfied with or without the secondary reference . The Examiner notes that if there is no support in the specification for clarifying the claims, then the Examiner cannot allow new matter to be used as a support for clarifying the claims or for obtaining allowance.
On page 9-11 the Applicant argues “The Applicant submits that the Office Action does not provide an adequate motivation to combine Stange and Prineas. The stated rationale of obtaining a broader emission spectrum identifies only a desired result, not an articulated reason with rational underpinning for modifying the Group IV GeSn p-i-n LED of Stange using the III-V cascaded/tunnel-junction architecture of Prineas. The rejection does not explain why a person of ordinary skill would have implemented the III-V cascade approach of Prineas into the configuration of Stange while still arriving at a silicon-compatible stack in which each coextending buffer and photoactive layer comprises at least two Group IV elements and is configured for emission based on relative concentration and strain. The proposed combination therefore relies on hindsight rather than on a teaching or suggestion in the cited art. LaChapelle does not cure the missing teachings of the combination of Strange and Prineas. The Office Action relies on LaChapelle only as evidence for general spectral-band definitions, including SWIR and MWIR ranges. General definitions of infrared bands do not disclose or suggest a Group IV GeSn-on-silicon LED, a stack of coextending buffer and photoactive layers, or the claimed dependence of emitted wavelengths on the relative Group IV concentration and corresponding strain of each layer. Stange, Prineas, and LaChapelle, taken alone and in combination, fail to teach, suggest, or disclose all the features of independent claim 190. Claims 191 and 203 to 207 all ultimately depend from and contain the limitations of independent claim 190. As such, Applicant respectfully requests reconsideration and withdrawal of the rejection of claims 190, 191, 203-207 under 35 U.S.C. § 103 over the combination of Strange and Prineas.”
The Examiner responds that emission of light and the teaching of composition based emission and the motivation of “to obtain a broader emission spectrum than is possible with only a single photoactive layer” is very strong motivation to combine and simply saying that the references are different is not a valid argument, when the device of the primary reference can be improved by applying the teaching of the secondary reference, and there is no hindsight because the Applicant’s invention is simply an application of the same teaching of the secondary reference and this is known to any person of ordinary skill in the art, thus there is no novelty in the instant Application and thus no hindsight is needed. The Examiner notes that if there is no support in the specification for clarifying the claims, then the Examiner cannot allow new matter to be used as a support for clarifying the claims or for obtaining allowance.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Bertrand et al. (see PTO-892 filed 11/6/2025 Bertrand et al., "Optoelectrical Characterizations of GeSn ...”) is provided as evidence of stacking different concentration GeSn layers for optoelectronic purposes.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to SITARAMARAO S YECHURI whose telephone number is (571)272-8764. The examiner can normally be reached M-F 8:00-4:30 PM.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Britt D Hanley can be reached at 571-270-3042. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/SITARAMARAO S YECHURI/ Primary Examiner, Art Unit 2893
Prosecution Insights