Quashing Parasitics in RF GaN-on-Silicon HEMTs

Why It Matters

By eliminating the parasitic channel, MST lets manufacturers deliver silicon‑based GaN RF HEMTs that combine low cost with performance previously limited to expensive SiC or SOI solutions, reshaping the RF market’s cost‑performance dynamics.

Key Takeaways

• Atomera’s MST cuts parasitic charge in GaN‑on‑silicon HEMTs >10×.
• MST enables -97 dBm second‑harmonic suppression, rivaling SOI benchmarks.
• Linear performance remains strong up to 40 dBm (10 W) input power.
• Integration requires only oxygen injection step, minimal fab disruption.
• Atomera monetizes MST via wafer royalties, a small fraction of value.

Pulse Analysis

The RF semiconductor landscape has long been split between high‑cost silicon‑carbide (SiC) platforms that deliver superior thermal performance and low‑cost silicon substrates that suffer from a parasitic charge layer. This parasitic channel, formed when aluminum and gallium atoms diffuse into the silicon during AlN nucleation, creates unwanted leakage paths that erode linearity and increase RF losses. Atomera’s Mears Silicon Technology (MST) tackles the root cause by pausing epitaxial growth to introduce a thin, oxygen‑rich layer that acts as a diffusion barrier. The result is a substrate whose resistivity exceeds 10 kΩ·cm, effectively eliminating the parasitic channel without resorting to full silicon‑on‑insulator (SOI) structures.

Independent measurements from Texas State University confirm MST’s impact: spreading‑resistance probes show interfacial charge reduced by more than an order of magnitude, and secondary‑ion‑mass‑spectrometry reveals dramatically lower gallium penetration. Performance metrics now rival SOI benchmarks, with second‑harmonic suppression reaching –97 dBm—comparable to Soitec’s best eSI10 product—while maintaining linearity at input powers up to 40 dBm (10 W). This breakthrough opens the door for cost‑sensitive applications such as 5G base stations and defense radars to adopt silicon‑based GaN HEMTs without sacrificing signal fidelity.

From a business perspective, MST’s integration is straightforward. Existing epitaxial tools need only an oxygen injection capability, akin to a strain‑engineering upgrade, keeping capital expenditures low. Atomera’s royalty‑based model aligns incentives, allowing wafer manufacturers to capture a modest share of the added value while passing performance gains to end‑users. As fabless designers and foundries begin to embed MST into standard process design kits, the technology could accelerate a shift toward affordable, high‑performance RF solutions, reshaping supply chains and competitive dynamics across the semiconductor industry.