Radiation-Aware Transport Modeling of AlGaN/GaN HEMTs for Robust RF Power Amplifiers in Extreme Environments

Modern satellite communications, defense radar systems, and deep-space missions rely on power amplifiers built from advanced semiconductor devices that must operate reliably despite constant exposure to space radiation. These devices, based on a material called gallium nitride, are essential to technologies such as GPS, weather forecasting, national defense, and exploration of the solar system, yet engineers do not fully understand how radiation changes the way electrical charge moves through these materials at the atomic level. Existing methods for predicting radiation damage rely on approximate, trial-and-error models rather than a fundamental physical understanding, making it difficult to design radiation-hardened electronics with confidence and forcing costly, time-consuming testing for every new mission. This project, a collaboration between Texas Tech University and Los Alamos National Laboratory, will develop a physics-based understanding of how radiation alters charge transport in these semiconductor devices and use that understanding to build a predictive design framework. This work directly benefits national and commercial space programs by reducing device qualification timelines from many months of testing to potentially a single confirmatory test, while strengthening the domestic supply of radiation-hardened electronics needed for national security and space exploration. As a project based at Texas Tech University, a designated Hispanic-Serving Institution, this program will engage undergraduate and graduate students from various backgrounds in hands-on research through the McNair program, pair them with mentors in a structured training pipeline, and introduce Lubbock-area high school students to semiconductor and space technology through a dedicated K-12 outreach workshop. AlGaN/GaN High-Electron-Mobility Transistors (HEMTs) are the enabling technology for RF power amplifiers in satellite communications, defense radar, and deep-space platforms, yet the mechanisms by which radiation reshapes intrinsic carrier transport in wide-bandgap semiconductors remain poorly understood. Current radiation-effects models rely on empirical curve-fitting rather than mechanistic understanding, limiting predictive Radiation-Hardness-by-Design capability. This 36-month program, conducted in collaboration with the Los Alamos National Laboratory Ion Beam Materials Laboratory via the CINT user program, tests three hypotheses: that radiation dynamically alters the knee-sharpness factor (γ), collapsing the assumed γ = 2 invariant used in all current compact models; that radiation reconfigures dominant scattering mechanisms, quantifiable through shifts in mobility exponent (α) and saturation velocity (vsat); and that atomistic defect densities can be deterministically linked to macroscopic transport shifts, enabling predictive compact modeling. Four integrated research thrusts execute this agenda: Gate Current Injection Method (GCIM)-based device screening; wide-temperature baseline characterization from 4 K to 550 K; proton irradiation at the LANL IBML up to 1015 p/cm2 across 2–6 MeV energies; and extension of the ASM-HEMT compact model with RF validation. Preliminary results using the PI's established GCIM and Unity-Intercept framework already show that γ is not static, with physics-extracted values increasing systematically with temperature (γ ≈ 4.5 at 4 K to γ ≈ 6.5 at 550 K), directly contradicting the γ = 2 assumption embedded in existing compact models. Extending this framework across the radiation-fluence dimension will establish deterministic scaling laws for mobility, saturation velocity, and knee-sharpness as functions of temperature and fluence, embedded in an open-source Radiation-Aware ASM-HEMT Library to predict post-irradiation RF performance without empirical adjustment after irradiation, a capability absent from any current compact modeling ecosystem. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.