Damage profiles in high-energy As implanted Si

Abstract

Deep distributions of lattice disorder induced in Si by room temperature, high-energy (3 MeV), nonamorphizing As ion implants have been characterized by Rutherford backscattering spectrometry channeling (RBS-C), double crystal x-ray diffractometry (DCXD), and cross-sectional transmission electron microscopy (XTEM). After accurate calibration of the measurement conditions, the depth positions of the profiles of displaced atoms, lattice strain, and XTEM weak-beam dark-field contrast in a sample implanted at a dose of 1014 As cm−2 agree within 3%. This confirms that the quantities measured by the three techniques have a similar qualitative correlation with the depth profile of as-implanted damage. The shape of the disorder profiles indicates different rates of damage accumulation as a function of depth, which have been characterized by a series of DCXD measurements at doses in the range 1012–1014 As cm−2. The problem of a quantitative determination of the number of defects is also addressed. In particular, the result of RBS-C, which gives as output the concentration of displaced atoms, is sensitive to the configuration of damage assumed when fitting experimental spectra. As a consequence, to give a reliable estimate of defect number a more refined microstructural model of damage (including, for instance, the deformation induced in the background lattice by heavily displaced atoms) should be used within the simulation of the measurement process.