Characterization of iron-implanted silicon carbide

Abstract

As part of extensive fundamental studies of ion-implanted ceramics, analytical electron microscopy (AEM) has been used to characterize [0001] single crystal 6H α-silicon carbide implanted at room temperature with 160 keV 57Fe ions to fluences of 1,3, and 6 x 1016 ions/cm2. AEM was performed at 100 kV with a Philips EM400T equipped with a field emission gun, a 6585 STEM unit, an EDAX 9100/70 energy dispersive X-ray spectrometer (EDS), and a Gatan 666 parallel-detection electron energy loss spectrometer (PEELS).A micrograph of a cross-sectioned specimen implanted with 6 × 1016 ions/cm2 is shown in Fig. 1. The implanted region extending to 195 nm from the surface is amorphous, as confirmed by convergent beam electron diffraction (CBED) patterns (insets), and contains iron at levels easily detectable by EDS (Fig. 2). The 15 nm lattice fringes of the edge-on 6H basal planes in the substrate provide an unambiguous depth calibration scale. The transition layer at the end of the ion range exhibits the expected strain contrast. The depth profile of the implanted iron was measured by EDS line scans perpendicular to the implant surface; the mean of three of these scans is shown by the filled symbols in Fig. 3. The integrated iron profile agrees with the expected 6.0 × 1016 ions/cm2 only if the density of the amorphous SiC is equal to that of its crystalline forms, rather than the 20% lower density reported earlier.