【Epitaxy Papers】Low-temperature plasma-enhanced atomic layer deposition of Ga₂O₃ films using N₂O plasma for silicon surface passivation

      Researchers from the St. Petersburg Alferov University have published a dissertation titled "Low-temperature plasma-enhanced atomic layer deposition of Ga₂O₃ films using N₂O plasma for silicon surface passivation" in Applied Surface Science.

Abstract

      This study investigates the deposition of gallium oxide (Ga₂O₃) thin films by plasma-enhanced atomic layer deposition (PE-ALD) using nitrous oxide (N₂O) as the oxidant for surface passivation of crystalline silicon. The deposition was performed at a low temperature of 75°C in a direct-plasma configuration, enabling conformal coating of substrates. Cross-sectional TEM confirmed the amorphous nature of the Ga₂O₃ films and the formation of a thin interfacial SiO_x layer at the substrate interface. STEM-EDX elemental mapping showed a homogeneous distribution of gallium and oxygen, along with traces of nitrogen and carbon, attributed to precursor–plasma interactions. Optical measurements revealed an optical bandgap of 4.52 eV, consistent with literature values for amorphous Ga₂O₃. It was found that the growth per cycle increased from 0.41 to 0.84 Å/cycle with increasing plasma power; however, higher power and extended plasma exposure deteriorated the passivation quality due to plasma-induced damage at the Ga₂O₃/Si interface. The maximum effective minority carrier lifetime reached 443 μs at a plasma power of 10 W (22 mW/cm²), indicating highly efficient passivation under low-damage deposition conditions. These results demonstrate the potential of N₂O-based PE-ALD Ga₂O₃ films as wide-bandgap, low-temperature passivation layers for next-generation silicon solar cells.

DOI：

https://doi.org/10.1016/j.apsusc.2025.165092