Quantitative electron channeling measurements for high sensitivity surface analysis

Abstract

Very high sensitivity to low dose implantation damage has been achieved by a novel quantitative analysis of electron channeling patterns (ECPs). An algorithm, based on the statistical analysis of the two-dimensional ECP pictures obtained from a scanning electron microscope, has been developed. The analysis yields a single number (the variance), analogous to the quantity χmin deduced from ion channeling measurements, which characterizes the surface crystallinity. Measurements performed on implanted silicon (point defects) and CdTe (extended defects) crystals show that electron channeling is approximately two orders of magnitude more sensitive to implantation damage than ion channeling. Changes in the ECP of Si and CdTe were observed after implantations with 200 keV Ar and 320 keV In ions at doses as low as 1×1012 cm−2 and 1×1013 cm−2, respectively. Moreover, electron channeling is capable of probing areas about four orders of magnitude smaller than commonly used ion channeling.