New ultrafast composite materials for the suppression of fast rise-time transient surges have been developed using atomic layer deposition (ALD). These devices are fabricated using a composite matrix of ALD-coated metal particles embedded in a nonconductive polymeric binder. Particle-particle junctions operate as Fowler-Nordheim (FN) tunneling junctions, allowing the quantum-mechanical conduction of charge carriers across the junction at raised electric fields, but preventing conduction under normal conditions. The ability of these ALD junctions to synchronously conduct tunneling currents leads to ultrafast transient response times of <1 ns, low capacitances of <50 pF, low leakage currents of <50 pA, and exceptionally high nonlinearity of ~250. These parameters are all markedly improved over traditional varistor material technology.