Formation of amorphous silicon by light ion damage

A model for formation of amorphous silicon by light ion implantation is proposed. It is suggested that accumulation of point defects and/or complexes is required at the initial stage of the amorphization process. Amorphous zone can only form at the end of incoming light ion tracks when the pre-accumulated concentration of point defects reaches a critical value. Depending on the uniformity of point defect distribution, two possibilities for the second stage of amorphization are suggested for the ion implantation at different temperature. Silicon wafers implanted with Boron ions at various temperatures with below and above the critical amorphization dose have been investigated using cross section specimens in high resolution TEM. The amorphization process has as well been studied by Electron Paramagnetic Resonance of the same samples investigated by transmission electron microscopy (TEM), allowing the identification of dangling bonds in amorphous zones and point defect clusters. (113), 1/3(111) extrinsic and other smaller distortion 1/x(111) stacking faults were also found during the amorphization process. Liquid nitrogen temperature and/or high beam current were found to be necessary to amorphizate Silicon by Boron ion implantation.