Invalidity dossier
US 5192987
Added 9/21/2026, 3:35:51 AM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 5,192,987
Title: High electron mobility transistor with GaN/AlₓGa₁₋ₓN heterojunctions
Patent number: US5192987A (application US07/701,792)
Assignee: APA Optics Inc. (original assignee). The source also lists current assignee entries "APA OPATICS Inc A Corp OF" and "Infineon Technologies Americas Corp," with a disclaimer that listed assignees may be inaccurate.
Key dates: Priority/filing date 1991-05-17; publication/grant date 1993-03-09; anticipated expiration 2011-05-17; status "Expired - Lifetime." A separate priority filing to US08/026,528 (US5296395A) is noted on 1993-03-03.
Inventors: Muhammed A. Khan, James M. VanHove, Jon N. Kuznia, Donald T. Olson.
Purpose: The invention "relates to a semiconductor device having improved electron mobility," specifically a transistor built from GaN/AlₓGa₁₋ₓN heterostructures "capable of operating at temperatures greater than 100° C." The stated rationale: AlₓGa₁₋ₓN has a bandgap roughly four times greater than AlₓGa₁₋ₓAs, giving "a lower noise current as the temperature of operation is increased." GaN is described as stable in air to 800° C.
Plain-language scope: A layered structure on a sapphire substrate includes an aluminum nitride buffer layer (to reduce lattice mismatch), a GaN layer, and an AlₓGa₁₋ₓN layer. Example thicknesses: substrate ~350 microns; GaN 3,000 Å (channel regions stated as 500–2,000 Å); AlₓGa₁₋ₓN ~450–500 Å; x ≈ 0.09. Source and drain ohmic contacts are photomasked and deposited, with a Schottky barrier between them, plus bonded connecting wires. Reported results include mobility rising from ~60 cm²/V·s (bulk GaN) to 620 cm²/V·s at room temperature and 1,600 cm²/V·s at 77° K, attributed to a two-dimensional electron gas at the interface. Figures show single and eighteen-period heterojunctions and mobility/temperature data.
What the excerpt does not establish: The supplied text is incomplete (explicitly marked "[Excerpt only…]") and gives no full claim language, no complete description, no figures, no examples of the eighteen-period structure's measured values, and no prior-art discussion.
Generated 10/1/2026, 10:02:39 PM
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Assignment history
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Prior art
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Obviousness
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Derivative works
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