High-fluence Si-implanted diamond: Formation of SiC nanocrystals and sheet resistance

Abstract

Effects of low-fluence swift iodine ion bombardment on the crystallization of ion-beam-synthesized silicon carbideThe sheet resistance and structural properties of high-fluence Si-implanted diamond were investigated. In order to minimize the radiation damage and to facilitate SiC formation the implantation was performed at 900°C. All samples were subsequently annealed in a rf-heated furnace at 1500°C for 10 min in order to remove defects and thermally unstable phases. X-ray diffraction, infrared absorption spectrometry, and high-resolution cross-sectional transmission electron microscopy revealed the formation of a buried layer inside the implanted diamond, which contains SiC nanocrystallites. These SiC nanocrystals have a cubic structure and are nearly perfectly aligned with the diamond lattice. Raman spectroscopy was applied to analyze radiation-damage-induced graphitization in dependence on the implantation conditions. The sheet resistance of the samples was measured as function of temperature by four point probe technique in van-der-Pauw geometry. The decrease of the sheet resistance with increasing ion fluence unambiguously shows the influence of implantation-induced damage. The behavior of the sheet resistance can strongly be modified by additional nitrogen implantation. The resulting higher conductivity is interpreted as partial incorporation of the nitrogen donor into the SiC nanocrystals. However, when the Si fluence exceeds a critical value of 5.3ϫ10 17 Si ϩ cm Ϫ2 at 900°C the diamond is irreversibly damaged and defect related conductivity dominates.

Direct fabrication of three-dimensional buried conductive channels in single crystal diamond with ion microbeam induced graphitization

“…A. V. Karabutov et al employed nitrogen implantation followed by thermal annealing to provide surface electrical conductivity to diamond microtips and improve their performance as field emitters [18,19]. Moreover, the possibility of creating effective ohmic contacts on doped or intrinsic diamond by high fluence implantation has been explored in several works [20,21,22,23,24]. Interestingly, while this research topic can be considered mature in terms of fundamental studies and technological applications, the possibility of fabricating buried graphitic channels, i.e.…”

n -type conductivity in high-fluence Si-implanted diamond

“…The diamond size was 3 ϫ 3 mm 2 and its thickness 0.25 mm. Fluences were chosen close to the critical fluence defined in our recent study 28 and ranged between 4.5ϫ 10 17 and 6.2 ϫ 10 17 Si cm −2 . The implantation flux varied between 3 and 10 A cm −2 .…”

“…The applied ion energy of 150 keV is high enough to create a 270-nm-thick, completely buried layer of a Si-rich phase 70 nm under the surface of the diamond, as shown earlier. 28 According to TRIM ͑Ref. 29͒ calculation the maximum Si atomic concentration in the buried layer varies between 29% for 4.5ϫ 10 17 Si cm −2 and 37% for 6.2 ϫ 10 17 Si cm −2 .…”

“…A more detailed study on the formation of epitaxially aligned 3C-SiC by high-dose Si implantation into diamond was published recently. 28 This study showed that the formation of a complete SiC layer is not possible without graphitization of the surrounding diamond. Graphitization is only inhibited below a critical Si fluence, which depends on implantation temperature and flux.…”

“…28 Additionally, the influence of unintentionally coimplanted nitrogen will be taken into consideration. The investigations are carried out using resistivity and Hall-effect measurements of high-fluence Siimplanted diamond in a wide temperature range.…”