Quantitative compositional depth profiling of Si 1− x− yGe xC y thin films by simultaneous elastic recoil detection and Rutherford backscattering spectrometry

Abstract

Elastic recoil detection in conjunction with time-of-flight spectroscopy (ERD-TOF) has been used to simultaneously depth profile all elements in thin SiGeC films on Si (0 0 1). Ge-rich Si 1− x− y Ge x C y (0.025 < (1 − x − y) < 0.08 and 0.026 < y < 0.216) films were grown by ultra-high vacuum ion beam sputter deposition. X-ray diffraction and transmission electron microscopy (TEM) showed that samples with low carbon concentration (typically, y ≤ 0.07) were single crystals with stacking faults and twins while films with 0.07 < y < 0.15 were polycrystalline. Samples with y > 0.15 were amorphous. There was no evidence of SiC precipitates. Ge depth profiles were obtained from the recoil spectra as well as from the Rutherford scattered Cl spectra in the same ERD-geometry. The H concentration was determined simultaneously by selective-absorber ERD. Films with C concentrations approaching a fraction of an at.%, and Si concentrations as low as ∼ 1 at.%, could be routinely depth profiled in a single experiment even in the presence of relatively strong surface contamination.