Modern FIB-Based Specimen Preparation for APT 203


Figure 12. Schematic of specimen-preparation-orientation options highlighting the impact on analysis volume, light absorption, heat flow, and potential voided regions within a tip (reprinted from (Martin et al., 2016) with permission).


access to the many NWAPT specimens resulting from such a process makes it easier to optimize APT analysis conditions and obtain data collection goals. Nevertheless, some NW properties are influenced by local growth conditions and geometry, so individually grown NWs on pillars may differ subtly from those grown in dense arrays. Analysis of these types of NW assemblies requires more generic specimen preparation solutions. Lift-out-type strategies for NW preparation have been


geometries where regions between NWs have been filled, enables lift-out and analysis without the same concern for ion damage (Prosa et al., 2010; Bran et al., 2013; Riley et al., 2013; Blumtritt et al., 2014; El Kousseifi et al., 2014; Padalkar et al., 2014). Protecting or encapsulating NWs to enable a nearly standard lift-out protocol has a number of advantages. First, it enables 3D targeting and orientation control of ROIs and buried interfaces. As the APT field-of-view does not include the entire specimen volume, encapsulating a NW moves the original surface toward the interior of the speci- men, capturing the region within the analytical field-of-view. Likewise, orienting that surface so that the NW axis is orthogonal to the analysis direction may improve spatial resolution of composition near the NW/coating interface. Finally, FIB-based Ga-damage may penetrate tens of nano- meters into the NW surface, interfering with analysis of those disturbed regions. Protecting the NW with a suitable material prevents this damage. It is also worth mentioning,


reported as well. For NWs with suitable dimensions, indivi- dual NWs can be extracted by cutting or plucking the NWs from the host substrate and attaching them to carrier tips (Agrawal et al., 2011; Eichfeld et al., 2012; Isheim et al., 2012; Sanford et al., 2014; Qu et al., 2015). Although care must be taken to prevent damaging exposure, to any ROI, by the ion beam during the NW cutting operation and subsequent aligning to a carrier tip, many successful analyses have been reported. Utilizing SEM-only imaging operations and electron-beam-deposits for attachment helps to minimize the potential for ion-beam damage. Protected or encapsulated lift-out, which includes NW


that FIB-based filling has the advantage that only the region being lifted-out is affected.


NPs


NPs and other open-space nanomaterials are a widespread class of technologically important materials. They are gen- erally incompatible with analysis by APT because the NPs are either too small to be individually transplanted and sharpened into an APT specimen, or because empty, voided regions contained within groups of NPs, or other open-space structures, are distributed in such a way that an APT tip cannot be made without being compromised by these structural defects (Larson et al., 2015). A few specimen pre- paration strategies have been reported in the literature (Folcke et al., 2012; Greene et al., 2012; Gordon et al., 2013; Felfer et al., 2014, 2015; Heck et al., 2014; Larson et al., 2015; Perea et al., 2016), but we will focus on two general strategies in this review. The first strategy takes sub-monolayer deposits of


particles on a substrate and covers them with a matrix or capping material (deposit and cover) (Folcke et al., 2012; Heck et al., 2014; Felfer et al., 2015). This covering process can include methods such as atomic layer deposition (ALD), where a space-filling structure is grown around deposited or grown NPs (Larson et al., 2015). The second strategy is to extract groups or clumps of


NPs, or other porous material, and attempt to fill in the voided regions by some method (Felfer et al., 2015). This second approach is important for many classes of materials including zeolites and semiconductor devices, where che- mically deprocessed volumes or other voided regions need to be replaced with an APT compatible material to maintain structural integrity during analysis. An example of the deposit and cover strategy was


reported by Heck et al. as they developed methods to prepare and analyze presolar, meteoric nanodiamonds (Stadermann et al., 2011; Heck et al., 2014, 2010). They attempted burying nanodiamonds using two different methods: standard lift-out


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164  |  Page 165  |  Page 166  |  Page 167  |  Page 168  |  Page 169  |  Page 170  |  Page 171  |  Page 172  |  Page 173  |  Page 174  |  Page 175  |  Page 176  |  Page 177  |  Page 178  |  Page 179  |  Page 180  |  Page 181  |  Page 182  |  Page 183  |  Page 184  |  Page 185  |  Page 186  |  Page 187  |  Page 188  |  Page 189  |  Page 190  |  Page 191  |  Page 192  |  Page 193  |  Page 194  |  Page 195  |  Page 196  |  Page 197  |  Page 198  |  Page 199  |  Page 200  |  Page 201  |  Page 202  |  Page 203  |  Page 204  |  Page 205  |  Page 206  |  Page 207  |  Page 208  |  Page 209  |  Page 210  |  Page 211  |  Page 212  |  Page 213  |  Page 214  |  Page 215  |  Page 216  |  Page 217  |  Page 218  |  Page 219  |  Page 220  |  Page 221  |  Page 222  |  Page 223  |  Page 224  |  Page 225  |  Page 226  |  Page 227  |  Page 228  |  Page 229  |  Page 230  |  Page 231  |  Page 232  |  Page 233  |  Page 234  |  Page 235  |  Page 236  |  Page 237  |  Page 238  |  Page 239  |  Page 240  |  Page 241  |  Page 242  |  Page 243  |  Page 244  |  Page 245  |  Page 246  |  Page 247  |  Page 248  |  Page 249  |  Page 250  |  Page 251  |  Page 252  |  Page 253  |  Page 254  |  Page 255  |  Page 256  |  Page 257  |  Page 258  |  Page 259  |  Page 260  |  Page 261  |  Page 262  |  Page 263  |  Page 264  |  Page 265  |  Page 266  |  Page 267  |  Page 268  |  Page 269  |  Page 270  |  Page 271  |  Page 272  |  Page 273  |  Page 274  |  Page 275  |  Page 276  |  Page 277  |  Page 278  |  Page 279  |  Page 280  |  Page 281  |  Page 282  |  Page 283  |  Page 284