This dataset identifies 355 patent families published between 2015 and mid-2026 that combine GaN HEMT or GaN transistor claims with epitaxial growth methods such as MOCVD or AlGaN barrier deposition. That figure counts families, which is the fairer unit than raw document counts because it neutralises repeat filings of the same invention across jurisdictions. The true figure for the most recent year is understated because publication lags filing by roughly 18 months.

The corpus shows activity concentrated among a mix of established semiconductor device makers, national research institutes, and university consortia, with the strongest co-assignee relationship linking an inter-university microelectronics centre to a partner university at 8 joint families. Notably, every assignee tracked for recent-year momentum shows zero families in the latest year, which given the publication lag likely reflects pipeline filings rather than firms leaving the space. Anyone doing competitive tracking should treat the current leaderboard as a historical snapshot rather than an active-filing ranking.

Device claims, classified mostly under H01L and H10D, describe the transistor structure itself — gate architecture, buffer stack, substrate integration — and cover 337 and 180 of the 355 records respectively. Epitaxy and crystal-growth process claims, classified under C30B, describe how the material layers are grown and appear in only 7 records. The heavy skew toward device structure claims means the process side of the technology carries comparatively less prior art density.

Filings in this corpus reached 38 in 2017, the highest point in the coverage window, then fell to 18 by the 2022 midpoint. That pattern is more consistent with core claim space filling in around established HEMT structures than with the technology losing commercial relevance — high filing density in the mid-2010s marks that space as occupied, not that the field stopped moving. The steep drop shown for 2025-2026 should be read as incomplete publication data rather than an actual halt in filing.

The IPC composition points toward crystal-growth process claims (C30B, 7 records), impedance and filter integration with HEMT devices (H03H, 7 records), and organic-semiconductor hybrid stacking (H10K, 8 records) as comparatively under-claimed relative to the dominant H01L device-structure cluster. A first claim in one of these branches would need to specify a process parameter or integration detail not already covered by the foundational heterojunction patents that anchor citation counts in this corpus. Confirming true openness still requires a targeted prior art search beyond this landscape view.