Sionyx, LLC v. Hamamatsu Photonics K.K.

330 F. Supp. 3d 574
District Court, District of Columbia·Decided August 30, 2018·No. Civil Action No. 15-13488-FDS·Published·Cited by 22 cases

Opinion

I. Background

A. Factual Background

The following facts appear to be undisputed.

1. The Parties

SiOnyx, LLC was founded in 2006 by Eric Mazur, a physics professor at Harvard University, and James Carey, his former doctoral student. (ECF 337-40 at 7:5-6, 8:3-9:7). Their goal was to commercialize laser-textured black silicon photodetectors, which had been the topic of Carey's Ph.D. dissertation and postdoctoral work in Mazur's laboratory. (ECF 337-40 at 9:15-11:11). Stephen Saylor joined SiOnyx in the fall of 2006 as President and CEO. (ECF 337-40 at 9:8-14).1 SiOnyx owns U.S. Patent No. 8,680,591, which it asserts in this lawsuit. (ECF 163-2 ¶¶ 12-17, 19).

The President and Fellows of Harvard College ("Harvard") are the assignees of the other patent asserted in this lawsuit, U.S. Patent No. 8,080,467, which covers Mazur and Carey's work.2 SiOnyx is the exclusive licensee of that patent. (ECF 342 Ex. G).

Hamamatsu Photonics K.K. is a Japanese integrated photonics company that researches, develops, and manufactures *582optical devices and image sensors. (ECF 163-2 ¶¶ 54-55; ECF 178 ¶¶ 54-55; ECF 337-41 at 114:5-18). It is the assignee of U.S. Patent Nos. 8,564,087 ; 8,629,485 ; 8,742,528 ; 8,884,226 ; 8,916,945 ; 8,994,135 ; 9,190,551 ; 9,293,499 ; and 9,614,109, in addition to several Japanese patents covering similar inventions. (ECFs 337-22 through 337-31).

Hamamatsu Corporation ("HC") is the marketing and sales company responsible for distributing HPK's products in North America. (ECF 97 at 3). It is a New Jersey corporation with its principal place of business in New Jersey. (ECF 97 at 3). HC is a wholly owned subsidiary of Photonics Management Corp., which is a holding company owned by HPK. (ECF 97 at 3, 13). HC purchases products from HPK at a price set by HPK. (ECF 97 at 3; ECF 382-1 at 62:21-65:7). HC has the authority to set its own resale prices, and it separately profits from its sales to end users. (ECF 97 at 3; ECF 382-1 at 62:21-65:7).

Ocean Optics is a Florida corporation with its principal place of business in Florida. (ECF 163-2 ¶ 6). It primarily sells spectrometers, some of which incorporate photodiodes purchased from HC. (See ECF 529-2 at 6, 9; ECF 529-3 at 107:13-108:20, 146:2-11).

2. The Technology at Issue

The technology at issue involves silicon photodetectors where one surface has been irradiated by a pulsed laser beam.

The photodetectors use p-n photodiodes, which work by transforming light into electrical current. The photodiode is formed from a silicon semiconductor substrate that has two types of charge-neutral impurities: (1) those that donate electrons (n-type impurities) and (2) those that accept electrons (p-type impurities), which can be said to have electron "holes." (ECF 377-1 at 87). When n-doped silicon is placed next to p-doped silicon, it creates a p-n junction, around which the electrons and holes rearrange themselves until they reach an equilibrium. (ECF 377-1 at 88-89). At equilibrium, there is a thin insulating layer at the juncture where the electrons and holes (charge carriers) have recombined (depletion region), and an electric field-created by the ions left behind when the electrons and holes diffused away-preventing further diffusion. (ECF 377-1 at 89; see ECF 201 at 13:10-14:20).

The outermost electrons associated with the silicon substrate are said to be in the "valence band," and have a certain energy. The next-highest energy state available is in the "conduction band." The difference in energy between the valence band and the conduction band is a physical property of the semiconductor material; for silicon, the band-gap energy is about 1.07 eV, which corresponds to light with a wavelength around 1100 nm. (ECF 377-1 at 1, 63-64).

If a photon of sufficient energy (that is, for silicon, one with a wavelength of less than 1100 nm) interacts with the silicon substrate, it may transfer its energy to an electron in the valence band and promote it to the conduction band; in other words, the photon is absorbed. (ECF 377-1 at 63; see ECF 201 at 10:21-11:21). Higher-energy photons will be absorbed closer to the light-incident surface, while lower-energy photons are absorbed deeper in the substrate. (ECF 386 Ex E at HPK0022535; see ECF 201 at 12:8-13:9, 15:11-16:16).

When a photon is absorbed, it creates an electron-hole pair (by promoting an electron to the conduction band). (ECF 377-1 at 93). If the photon is absorbed in the depletion region of the photodiode, the electron and the hole are immediately separated because of the electric field, which creates a current. (ECF 377-1 at 93-94). Photons absorbed too far away from the depletion region are much less likely to *583produce a current. (ECF 201 at 15:11-16:16).

Thus, in an ordinary p-n photodiode, light enters through one surface of the photodiode and, to some extent, is absorbed in the depletion region, resulting in electric current. (ECF 377-1 at 63). Light that is not absorbed will either go right through the photodiode (in which case it does not contribute to the sensitivity of the photodiode) or reflect off the back surface of the photodiode back into the photodiode, in which case it has another opportunity to be absorbed and turned into current. ( '109 patent, col. 7 ll. 24-34). Whatever portion of that light is still unabsorbed after a second trip through the photodiode will either pass through the light-incident surface (again without contributing to the sensitivity of the photodiode) or be reflected by that surface, and so on. ( '109 patent, col. 7 ll. 34-37). Infrared light is more likely to go through the photodiode without being absorbed than visible light, because its longer wavelength (and correspondingly lower energy) is absorbed deeper in the substrate and its energy may be insufficient to bridge the band gap of the silicon semiconductor. (ECF 377-1 at 6-7, 63-64; see ECF 201 at 9:3-13; 12:1-7).

The technology at issue seeks to improve the sensitivity of the photodiode to near-infrared light by irradiating a surface of the silicon substrate with a laser. That irradiation creates an irregular texture on the surface, so that, instead of being smooth, it has micro- or nanometer-scale features that cause the surface to look black to the human eye. (ECF 377-1 at 6-7). Changing the parameters of the irradiation protocol can change the size and shape of those features. (ECF 377-1 at 55 tbl.3.2).

When applied to the back surface of a photodiode, the irregular asperity has the effect of improving the sensitivity of the photodiode to infrared light. In that case, the light enters the photodiode from one surface, and, as before, some is absorbed by the substrate. But instead of meeting a smooth surface on the backside of the photodetector, the unabsorbed light meets the irregular asperity.

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Sionyx, LLC v. Hamamatsu Photonics K.K., 330 F. Supp. 3d 574 (D.D.C. 2018).

330 F. Supp. 3d 574 (Sionyx, LLC v. Hamamatsu Photonics K.K.) — published by Counsel Stack Legal Research, free access to 12M+ legal documents.

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