Oral Presentation 26th ACMM “2020 Visions in Microscopy”

JEM-ARM300F is our latest aberration corrected 300kV microscope with cold field emission electron gun. This microscope can be equipped with one of two objective lens pole-pieces; WGP (Wide Gap Pole-piece) or FHP (Full High resolution Pole-piece). WGP provides an ultra-highly sensitive X-ray detection system with two windowless silicon drift detectors (SDDs). FHP is utilized for ultra-high resolution imaging.

Fig.1a shows high angle annular dark field (HAADF) image of GaN [211], averaged with 20 sequential raw images obtained by JEM-ARM300F with FHP2 and 3rd order spherical aberration corrector at 300kV. The Ga to Ga dumbbell of 63 pm is clearly resolved. The fast Fourier transform (FFT) pattern of the image exhibits spots of (45 pm)-1 as well as (48 pm)-1 as shown in Fig.1b. These results suggest the FHP2 configuration keeps ultra-high resolution imaging capability, similar to the FHP. Two windowless SDDs (dual SDDs) with 158 mm2 wide insensing area are attachable for the FHP2, similar to WGP configuration. The total collection solid angle reaches 1.4 sr, around 2 times higher than that of previous FHP configuration equipped with 100 mm2-sized dual SDDs (0.7 sr). Take-off angles of detectors are also raised to be 26 degrees from previous configuration (~16 degrees). The raised take-off angle minimizes shadowing effect due to specimen holder and/or sample surface roughness, and increases effective X-ray intensity. Figure 3 shows atomic resolution EDS maps (Wiener filtered) for GaN [211] obtained at 300 kV. Both nitrogen and gallium atomic column are clearly visible. Most of Ga to Ga dumbbells of 63 pm are resolved suggesting the spatial resolution of an EDS elemental map reaches better than 63 pm. The aberration corrected 300kV microscope with the new objective lens pole-piece (FHP2) shows capabilities of ultra-high resolution below 50 pm in HAADF image and EDS elemental map of Ga.