Radiation-induced defect accumulation and annealing in Si-implanted gallium oxide

Defect accumulation and annealing phenomena in Si-implanted monoclinic gallium oxide (beta-Ga2O3) wafers, having ((2) over bar 01), (010), and (001) orientations, were studied by Rutherford backscattering spectrometry in channeling mode (RBS/c), x-ray diffraction (XRD), and (scanning) transmission electron microscopy [(S)TEM]. Initially, the samples with different surface orientations were implanted with 300 keV Si-28(+)-ions, applying fluences in the range of 1 x 10(14)-2 x 10(16) Si/cm(2), unveiling interesting disorder accumulation kinetics. In particular, the RBS/c, XRD, and (S)TEM combined data suggested that the radiation disorder buildup in Si-implanted beta-Ga2O3 is accompanied by significant strain accumulation, assisting crystalline-to-crystalline phase transitions instead of amorphization. Selected samples having ((2) over bar 01 ) orientation were subjected to isochronal (30 min) anneals in the range of 300-1300 degrees C in air. Systematic RBS/c and XRD characterization of these samples suggested complex structural transformations, which occurred as a function of the fluence and the temperature. Moreover, a detailed (S)TEM analysis of the sample implanted with 2 x 10(16) Si/cm(2) and annealed at 1100 degrees C was enhanced by applying dispersive x-ray and electron energy-loss spectroscopies. The analysis revealed silicon agglomerations in the form of silicon dioxide particles. Signal from silicon was also detected outside of the agglomerates, likely occurring as substitutional Si on Ga sites. Published under an exclusive license by AIP Publishing.