X-ray Standing Waves and Rutherford backscattering Studies of the Structure of Si Single Crystals Implanted with Fe Ions

Abstract

The X-ray standing wave and Rutherford backscattering spectroscopy in channelling geometry were applied for the investigation of the structure of silicon single crystals implanted with 80 keV Fe ions. Both methods were used for the determination of crystal damage and lattice location of implanted metal atoms before and alter thermal annealing. Both methods gave consistent results regarding the amorphization of Si due to the Fe-ion implantation. Moreover, using both methods some Fe substitution fraction was determined. The depth profiles of implanted atoms were compared to the results of computer simulations. Complementary use of X-ray standing wave and Rutherford backscattering spectroscopy channelling techniques for studies of radiation damage and lattice location of implanted atoms is discussed.

Theory and applications of x-ray standing waves in real crystals

“…The minimum on curve 1 occurs because field 1 does not interact with impurities and field 2 is not excited in this angular region. If impurity atoms are randomly distributed [in (86), exp(−W a ) = B = 0], this effect is compensated entirely by increasing the interaction with field 1 (curve 2 in Fig. 28b).…”

“…Described above approach of multilayer crystal was used in the papers [85,86] where silicon crystals were implanted with F e and N i ions and analysed with XSW technique and Rutherford backscattering (RBS) method. The XSW technique was applied previously [8,58,87] for structure investigation of Si crystals after implantation with the different impurity atoms (As, Bi).…”

“…However, in this papers more simplified model of the damaged crystal was assumed. Below, following the papers [85,86], we will discuss in details results of XSW analysis of silicon single crystals implanted with F e ions (dose 5 × 10 15 ions/cm 2 at an energy of 80 keV). After ion implantation samples were annealed at 750 • in the N 2 atmosphere.…”

“…From Ref. [86]. obtained as a result of the phase retrieval from the angular dependence of the photoemission yield and reflectivity (Fig.…”

Lattice sites of implanted Fe in Si

“…It was concluded that the EXAFS results are consistent with Fe being located at a distorted interstitial site. Vartanyantz et al 29 investigated Si implanted with 5 ϫ 10 15 cm −2 of Fe at 80 keV and annealed at 750°C using Rutherford backscattering spectroscopy and channeling ͑RBS/C͒ They found that the RBS signal from Fe was reduced by 30% for ͗111͘ channeling incidence, from which they concluded that 30% of Fe would be located on substi-tutional sites. However, this conclusion is ambiguous since reductions in the backscattering yield for ͗111͘ channeling may result not only from substitutional but also from a large variety of interstitial sites in Si.…”