GaN HEMT Device Physics Knowledge Base

A compact LLM wiki on gallium-nitride HEMTs: polarization-induced 2DEG physics, high-field behavior, traps, reliability, RF/power use cases, and 2023–2026 research directions.

Last updated: 2026-05-11 · static LLM wiki

Why this matters

GaN HEMTs are not just faster silicon transistors. Their behavior starts with polarization physics in wurtzite III-nitrides: fixed interface charge creates a high-density two-dimensional electron gas without intentional channel doping. That gives excellent current density and switching/RF speed, but it also makes the device sensitive to surfaces, traps, electric-field shaping, buffer design, thermal gradients, and gate-stack choices.

This knowledge base is organized as interlinked notes rather than a single article. Start with the fundamentals, then branch into reliability, normally-off gates, thermal design, RF/power applications, and current research.

Map of the wiki

FundamentalsMaterial properties, heterostructure stack, and why GaN is useful. Polarization & 2DEGSpontaneous/piezoelectric polarization, charge balance, band diagrams. Transport & high-field physicsMobility, velocity saturation, field plates, leakage, breakdown. Traps & reliabilityCurrent collapse, dynamic R_ON, V_TH shift, JEDEC tests. Normally-off gatesp-GaN, MIS/recessed gates, cascodes, and gate reliability. Thermal & packagingSelf-heating, substrates, GaN-on-diamond, layout, integrated drivers. RF vs power applicationsDifferent optimization targets, substrates, commercial state of the art. Latest research2023–2026 trends: p-GaN reliability, vertical GaN, AlN, β-Ga₂O₃, diamond.

One-sentence mental model

A GaN HEMT is a polarization-engineered, high-field lateral transistor whose biggest strengths are high charge density and high speed, and whose biggest practical limits are traps, heat, field crowding, and gate/buffer reliability.