Cross-sectional transmission electron microscopy method and studies of implant damage in single crystal diamond

Abstract

Few transmission electron microscopy ͑TEM͒ studies of single crystal diamond have been reported, most likely due to the time and difficulty involved in sample preparation. A method is described for creating a TEM cross section of single crystal diamond using a focused ion beam and in situ lift-out. The method results in samples approximately 10 m long by 3 m deep with an average thickness of 100-300 nm. The total time to prepare a cross-sectional TEM sample of diamond is less than 5 h. The method also allows for additional thinning to facilitate high resolution TEM imaging, and can be applied to oddly shaped diamond samples. This sample preparation technique has been applied to the study of ion implantation damage in single crystal diamond and its evolution upon annealing. High-pressure-high-temperature diamonds were implanted with Si + at an energy of 1 MeV and a temperature of 30°C. One sample, with a ͑110͒ surface, was implanted with a dose of 1 ϫ 10 14 Si cm −2 and annealed at 950°C for 10 and 40 min. No significant defect formation or evolution was discernible by cross-sectional transmission electron microscopy. Another sample, with a ͑100͒ orientation, was implanted with 1 MeV at 1 ϫ 10 15 Si cm −2 and annealed at 1050°C for 10 min. Prior to annealing, a heavily damaged but still crystalline region was observed. Upon annealing, the sample showed no signs of conversion either to an amorphous form of carbon or to graphite. This is unexpected as the energy and dose are above the previously reported graphitization threshold for diamond. Higher annealing temperatures and possibly a high vacuum will be required for future study of defect formation, evolution, and phase transformations in ion-implanted single crystal diamond.

Reactive ion etching: Optimized diamond membrane fabrication for transmission electron microscopy

“…33 Using a gallium-ion beam at 30 keV, two 6-lm-deep trenches were milled into diamond, as shown in the inset image of Fig. Prior to any fabrication, the samples were exposed to a boiling 1:1:1 nitric:sulfuric:perchloric (HNO 3 :H 2 SO 4 :HClO 4 ) acid mixture.…”

“…[17][18][19][20][21] For example, the negatively charged nitrogen-vacancy center (NVC) in diamond is one of the most promising candidates for solid-state qubit due to its fast optical initialization, readout, and long spin-coherence time at room temperature. [31][32][33] FIB-based techniques rely on physical bombardment of the sample surface by high-energy gallium ions. [27][28][29][30] Diamond damage due to ion implantation has been examined with TEM using a) Electronic mail: ll2670@columbia.edu b) Electronic mail: englund@mit.edu FIB-produced membrane samples.…”

Investigation of focused ion beam induced damage in single crystal diamond tools

“…To avoid the charging effect, a thick Pt cover was further deposited on the irradiation area through ion-beam Pt deposition. The cross-sectional TEM sample was prepared using the standard lift-out technique, described in [34]. The final TEM sample is shown in figure 3 (a).…”

Molecular dynamic simulation of low-energy FIB irradiation induced damage in diamond

“…The Pt stripes were used to avoid the charging effect and to protect the formed damage layer from additional Ga + irradiation during the following sample preparation procedure. The cross-sectional TEM sample was prepared using the standard lift-out technique described elsewhere [13] ( figure 3 (b)-(c)). The sample was further thinning to electron transparency with the thickness less than 100 nm ( figure 3 (d)).…”

“…nanostructures [11,12], and preparation of specimen used in transmission electron microscopy (TEM) [13]. However, apart from the controlled removal of target material, the exposure of material to FIB (typically 2-30 kV) will result in surface and near-surface radiation damage due to the atomic displacements and the implantation of ion source material.…”