Pulsed laser deposition DC plasma-assisted of GaAsN thin films

Abstract

GaAsN thin films were synthesized via pulsed laser deposition with DC glow discharge plasma activation in an Ar/N₂ atmosphere. The effect of background pressure 0.5–10 Pa on film morphology, structure, and optical properties was systematically evaluated. Increasing pressure enhanced nitrogen incorporation up to 2.3 at.%, concurrently reducing the direct bandgap from 1.20 eV to 1.065 eV. Pressures exceeding 5 Pa degraded surface smoothness and growth rate due to plasma plume scattering. An optimal pressure of 5 Pa on GaAs(100) substrates yielded oriented growth with minimal droplet density, superior to polycrystalline films on Si(111). Comparative optical characterization at this optimal condition confirmed that the fundamental bandgap narrowing is primarily governed by nitrogen incorporation kinetics driven by background pressure, independent of substrate type. This approach enables synthesis of optoelectronic grade dilute nitrides at temperatures 350 °C.