RADIATION EFFECTS IN ION IMPLANTED beta-Ga2O3

Abstract

Ion implantation induced effects are studied in -Ga2O3 at room temperature. The main technique applied is Rutherford backscattering spectrometry in channelling configuration (RBS) using He ions. Additionally, selected samples were investigated by optical spectroscopy and transmission electron microscopy (TEM). For the implanted P, Ar or Sn ions clear damage peaks are visible in the RBS spectra. The concentration of displaced lattice atoms in the maximum of the distribution (as deduced from the channelling spectra) increases almost continuously up to a saturation value of about 90% with increasing ion fluence. Once this level is reached in the maximum of the distribution, during further implantation a broadening of the distribution occurs with the concentration remaining at this level. RBS measurements performed with different energy of the analysing He ions reveal that the damage produced is characterized by randomly distributed lattice atoms. This indicates point defects, point defect complexes or amorphous zones. As the channelling spectra of the implanted layers do not reach the random level, complete amorphisation can be excluded. Furthermore, the applied optical techniques do not exhibit significant changes in comparison to the signal measured for the unimplanted sample even though these studies were performed for the highest ion fluences implanted. Cross sectional TEM confirms this result. The diffraction pattern shows clear spots as for the unimplanted material and extended defects are almost not visible. The -Ga2O3 layers ion implanted at room temperature contain mainly point defects the strong influence of which on the dechannelling of the He ions in the RBS analysis is not yet understood.