Electron Paramagnetic Resonance Studies of Shallow Donors Behavior in Hydrogenated ZnO Films

摘要

Photoassisted metalorganic chemical vapor deposition (photo-MOCVD) technique was used for depositing of as-grown (ZnO) and hydrogenated (ZnO:H) zinc oxide polycrystalline thin films under different growth and hydrogen doping conditions. The structure and morphology of the films was controlled using SEM and AFM microscopy and surface roughness measurements. The studies of paramagnetic defects behavior and magnetic susceptibility in as-grown and hydrogenated samples were provided in the temperature range 77-300 K using X-band EPR spectrometer. It was found that all the samples exhibited a single symmetric strong Lorentzian line at g = 1.96 while the line intensity was shown to increase upon H-doping. The concentration of paramagnetic defects, associated with the concentration of the hydrogen donors, was extracted. The behavior of the magnetic susceptibility curves was described by Curie and Pauli contributions. We have shown that the excess concentration of paramagnetic defects, appeared after hydrogen doping, correlated with the increase of the Pauli term of magnetic susceptibility and followed the increase of free carrier concentration.