DETAILED ACTION
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) 1-8 and 10-15 are rejected under 35 U.S.C. 103 as being unpatentable over Kako et al. (JP 2003218386A) in view of Chen et al. (CN 102299224A; on IDS).
Regarding independent claim 1, Kako teaches an epitaxial structure for light emitting diode (Fig. 1; para. 0029-0034) characterized in that the epitaxial structure for light emitting diode comprises
a substrate (2), a buffer layer (para. 0030), a distributed Bragg reflector (3), and a semiconductor stack (4/5/6/7) in an order from bottom to top (para. 0030-0031),
wherein the distributed Bragg reflector includes a low refractive-index film (AlInP) and a high refractive-index film (GaAs) above the low refractive-index film, and
a thickness of the high refractive-index film is thinner than an optical thickness of the high refractive-index film (para. 0032).
Kako does not teach wherein the high refractive-index film comprises: a first high refractive-index film; and a second high refractive-index film disposed on the first high refractive-index film, wherein a composition ratio of Al of the second high refractive-index film is not higher than that of the first high refractive-index film.
Chen teaches a similar device (Fig. 6) wherein the high refractive-index film (32) comprises: a first high refractive-index film (34); and a second high refractive-index film (38) disposed on the first high refractive-index film, wherein a composition ratio of Al of the second high refractive-index film is not higher than that of the first high refractive-index film (para. 0040).
It would have been obvious to one of ordinary skill in the art at the time of filing to modify the Bragg structure of Kako as taught by Chen such that the high refractive-index film of Kako comprised a first high refractive-index film and a second high refractive-index film above the first high refractive-index film wherein a composition ratio of Al of the second high refractive-index film is not higher than that of the first high refractive-index film as taught by Chen for the purpose of improving light extraction of the device; that is providing a Bragg structure with high reflectivity and large reflection bandwidth (Chen para. 0040).
Re claim 2, Kako teaches the distributed Bragg reflector is a periodic structure consisting of the low refractive-index film and the high refractive-index film, and a number of periods of the distributed Bragg reflector is 20 (para. 0034), which is within the claimed range of 10 to 100 and therefore anticipates the range (MPEP 2131.03, I).
Re claim 3, Kako teaches wherein the low refractive index film is AlInP (para. 0034) instead of wherein the low refractive-index film comprises AlzGa1-zAs, where 95%≥z≥100%.
Chen teaches that other low index refraction films are known including AlAs (para. 0040) which is within the claimed range of AlzGa1-zAs, where 95%≥z≥100% and therefore anticipates the range (MPEP 2131.03, I).
It would have been obvious to one of ordinary skill in the art at the time of filing to predictably substitute the AlInP of Kako with the AlAs of Chen for the purpose of providing the low-index refraction layer of the Bragg structure to arrive at the claimed invention (MPEP 2143, I, B). Furthermore, the selection of a known material based on its suitability for its intended use supported a prima facie obviousness (MPEP2144.07).
Re claim 4, Kako teaches wherein the thickness of the low refractive-index film is thicker than an optical thickness of the low refractive-index film by d1, and a range of d1 is 0.1D1 to 0.5D1 (calculated from formula provided para. 0032) which overlaps with the claimed range of 0.05 D1 to 0.4D1, where D1 is the optical thickness of the low refractive-index film, and D1=λ/4N1, N1 is a refractive index of the low refractive-index film, and λ is a central reflection wavelength (para. 0033).
It would have been obvious to one of ordinary skill in the art at the time of filing to operate within the overlapping range for determining the thickness of the low refractive-index film. Furthermore, in the case where the claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists (MPEP 2144.05).
Re claim 5, Kako teaches a specific example wherein the thickness of the low refractive-index is 71nm (para. 0034); however, Kako further teaches the thickness of the film is adjustable and dependent upon the wavelength of the light to be reflected and the material of the reflecting layer (para. 0032).
It would have been obvious to one of ordinary skill in the art at the time of filing to optimize the thickness of the low refractive-index layer such that it ranged from 30nm to 70nm as claimed for the purpose of optimizing light extraction of the device -- when the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation (MPEP 2144.05, II).
Re claim 6, Kako in view of Chen teaches wherein thickness and composition of the first high refractive-index film are different from those of the second high refractive-index film (Chen para. 0040).
Re claim 7, Kako in view of Chen teaches wherein the first high refractive-index film comprises AlyGa1-yAs, where 100%≥y≥45% (Chen para. 0040) which overlaps with the claimed range of 70%≥y≥50%.
It would have been obvious to one of ordinary skill in the art at the time of filing operate within the claimed range because the prior art teaches that these are acceptable values and; furthermore, in the case where the claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists (MPEP 2144.05).
Re claim 8, Kako in view of Chen teaches wherein the second high refractive-index film comprises AlxGa1-xAs, where 0.45≥x≥0.01% (Chen para. 0040) which overlaps with the claimed range of 65%≥x≥0.
It would have been obvious to one of ordinary skill in the art at the time of filing operate within the claimed range because the prior art teaches that these are acceptable values and; furthermore, in the case where the claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists (MPEP 2144.05).
Re claims 10 and 11, Kako in view of Chen may not explicitly teach that the thickness of the second high refractive-index film is thinner than an optical thickness of the second high refractive-index film by 2d2, and a range of d2 is 0.05 D2 to 0.4 D2, where D2 is the optical thickness of the second high refractive-index film, and D2=λ/4N2, N2 is a refractive index of the second high refractive-index film, and λ is a central reflection wavelength, wherein the thickness of the first high refractive-index film is d2; however, the limitation of “D2 is the optical thickness of the second high refractive-index film, and D2=λ/4N2, N2 is a refractive index of the second high refractive-index film, and λ is a central reflection wavelength” is simply a restating of scientific formula for the optical thickness of film at a given wavelength with a given refractive index and Kako and Chen both teach the thickness of the layers to be dependent upon this same formula (Kako para. 0032; Chen para. 0014-0018, 0038) and it would have been obvious to one of ordinary skill in the art at the time of filing to optimize the thicknesses of the layers for the purpose of maximizing light extraction such that the they arrived at the claimed limitation because when the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation (MPEP 2144.05, II).
Re claim 12, Kako in view of Chen teaches wherein the thickness of the second high refractive-index film may be 35nm (Chen para. 0040), which is within the claimed range of from 20nm to 60nm and therefore anticipates the range (MPEP 2131.03, I).
Re claim 13, Kako teaches wherein the substrate is a GaAs substrate (para. 0030).
Re claim 14, Kako teaches wherein the semiconductor stack comprises a first semiconductor layer (4), an active layer (5), a second semiconductor layer (6) and a window layer (7) which are formed in order on the distributed Bragg reflector (Fig. 1; para. 0030-0031 – refer to also to para. 0004 teaching that a current spreading layer is sometimes called a window layer).
Re claim 15, Kako teaches a light emitting diode (Fig. 1) comprising a first electrode layer (1), an epitaxial structure for light emitting diode according to claim 1 (refer to claim 1 rej.), a current spreading layer (7), and a second electrode layer (8) from bottom to top (para. 0030-0034; see also: Explanation of symbols).
Response to Arguments
Applicant argues that Kako does not teach having two discrete high-index films and discloses only a single high refractive-index film. The Examiner agrees as Chen is relied upon for this teaching.
Applicant argues Chen's structure involves a continuous refractive index grading within a single high- index layer, rather than dividing the high-index layer into two distinct sublayers with different Al compositions, wherein the upper sublayer has an Al composition not higher than the lower sublayer, as presently claimed. Applicant argues that in Chen's second embodiment (Fig. 6), the Al composition varies continuously across the layer thickness (para. [0040]), without forming a discrete interface or compositionally distinct subregions. Thus, Chen discloses only a single high refractive-index film with continuous composition gradient.
The Examiner disagrees with Applicant’s analysis. Chen does teach two distinct sublayers (34, 38) with different Al compositions, wherein the upper sublayer has an Al composition not higher than the lower sublayer (para. 0040 – the upper sublayer has an Al composition of 0.45, which is the same as (i.e. “not higher”) the highest Al composition as the lower sublayer. While the Examiner agrees that the lower sublayer of Chen is graded (the upper is not) as opposed to having a constant or single Al content throughout the layer; the claims, as currently written, do not require the lower sub-layer (or upper sublayer) to have a constant or single Al content throughout the layer(s); only that “a composition ratio of Al of the second high refractive-index film is not higher than that of the first high refractive-index film”.
Applicant argues the Kako reference teaches nothing about light absorption of the refractive-index film due to thickness and lattice mismatch with the adjacent low refractive-index film.
While the Examiner agrees that Kako may not discuss lattice mismatch, the Examiner notes that none of the claims make reference to lattice mismatch either. Kako does disclose the thicknesses of the layer(s) of the Bragg to have a result on the reflectance (high reflectance meaning low absorption) in para. (0032).
Applicant argues although Chen teaches a continuous Al gradient to broaden the DBR stop-band, even with this approach, a single high refractive-index layer still requires increased thickness to achieve the broadened stop-band, which may result in significant light absorption.
The Examiner does not agree that the Chen reference teaches a single high refractive-index layer as the high refractive-index layer (32) of Chen has two sublayers (34, 38) (Fig. 6; para. 0040). The Examiner is not sure how Applicant concludes Chen requires increased thickness as the disclosed thicknesses of Chen (para. 0040) are on par with Applicant’s (claim 12).
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to MOLLY KAY REIDA whose telephone number is (571)272-4237. The examiner can normally be reached M-F 8:30-5:00PM.
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/MOLLY K REIDA/Examiner, Art Unit 2899
/Brent A. Fairbanks/Supervisory Patent Examiner, Art Unit 2899
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