Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology Yongho Seo Wonho Jhe School of Physics and Center for Near-field Atom-photon technology, Seoul Nation University in South Korea Scanning Probe Microscopy Using Quartz Crystal Resonator

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology High Frequency (rf) Thickness Shear k = N/m High Speed Low Frequency (32 kHz) Flexural Mode k = N/m High force sensitivity Z-cut Tuning fork AT-cut QCR Z-cut trident QCR QCRs as a Force Sensor High Frequency (1 MHz) Extensional mode k = N/m High resolution

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology -Shear mode - 2 MHz dithering frequency - make a hole to insert optical fiber tip - easy to replace tip - increased the stability - high Q-value > 10 3 High Speed NSOM

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology Optical image of Grating Total time : 0.5 s 7x7  m 2 Optical image of Grating Total time : 0.5 s 7x7  m 2 Fastest Scanning NSOM Image Topography of CD Total time : 20 s Topography of CD Total time : 20 s Y. Seo, et. al, Appl. Phys. Lett (2000).

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology Slowly diffusing micro-spheres in water Scanning time 25 s, 5 x 4  m 2 0 min. Continuous Images using High Speed Shear Force Microscope 3 min.6 min.9 min.12 min Y. Seo and W. Jhe, Rev. Sci. Instrum. 73, 2057 (2002)

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology f = KHz k = 1300 N/m f = KHz k = 1300 N/m Tuning Fork Based Electrostatic force microscopy -Ferroelectrics -surface charge in Semiconductor L = 2.2 mm, t = 190  m, w = 100  m k = 1300 N/m. Q = 1800, f = 32 kHz

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology minimum detectable force = (k/Qf) 1/2 f = kHz k = N/m Q = ~ 10 nm dithering f = kHz k = N/m Q = < 1 nm dithering Si CantileverQuartz Tuning Fork Force Sensitivity of Quartz Tuning Fork Long range electrostatic force Short range shear force keep constant gap between tip and sample (~10 nm) to avoid the strong short range topographic contrast Lift mode

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology H 3 PO 4 - Co or Ni wire Pt Co, Ni D = 100  m10  m Tip Manufacture Electrochemical Etching

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology -Attach the wire to the tuning fork and make a tip -Use home-made micromanipulator Pt Co, Ni H 3 PO 4 Tuning fork Silver paint Tip Attachment

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology for high quality nano storage devices : high ferroelectric properties long term stability and reliability PZT (100 nm) / Pt electrode layer / Si substrate Ferroelectric PZT Thin Film

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology Bias voltage applied between the tip and Pt substrate PZT Pt Tip Approach Curve in EFM

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology 7 x 7  m x 0.9  m 2 polarization poling Line drawing long time stable (10 hr) long time stable (10 hr) High resolution (50 nm) narrow line width High resolution (50 nm) narrow line width Poling and Drawing by EFM

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology Tuning Fork based EFM - polarization images 4 x 4  m 2 7 x 7  m 2 Patterning and Imaging by EFM Y. Seo, et al, Appl. Phys. Lett , (2002).

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology Frequency shiftPhase shift MFM contrast - magnetic force gradient between tip and sample Lift mode - keep constant gap between tip and sample (~10 nm) - to avoid the strong short range topographic contrast Magnetic force - very weak force (~pN) Force gradient Tuning Fork Based Magnetic Force Microscopy

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology Approach Withdraw high S/N ratio high frequency Sensitivity < 3 mHz Shear force attractive force Approach Curve of MFM

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology L = 2.2 mm, t = 190  m, w = 100  m spring constant, k = 1300 N/m Co or Ni tip Tip & Tuning Fork epoxy

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology - Perpendicularly recorded sample -longitudinally polarized tip - monopole approximation Advantage of the shear mode MFM Shear Mode MFM

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology (a) shear mode, Co tip, perpendicular (b) shear mode, Co tip, parallel dithering (c) shear mode, Ni tip (d) tapping mode (a) shear mode, Co tip, perpendicular (b) shear mode, Co tip, parallel dithering (c) shear mode, Ni tip (d) tapping mode 30 x 30  m Mbit / Inch 2 hard disk 100 Mbit / Inch 2 hard disk Magnetic Force Microscopy Images

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology Amplitude (a) dependency 3 x 1  m 2 13 x 3  m 2 Lift Height & Dithering Amplitude Height (h) dependency h a Tip Sample

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology 1 Gbit/inch 2 hard disk Dithering Amplitude : 20 nm lift height : 50 nm Spatial resolution : 50 nm 2 x 2  m 2 High Resolution Tuning Fork Based MFM

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology 160 x160 nm 2 Atomic layer (3Å) Atomic Layer of HOPG With Trident QCR (1MHz)

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology True Atomic resolution AFM in air Mica Ambient condition Non-contact AFM Dithering Amp: 0.1 nm Triangular structure k = 50,000 N/m Trident QCR, 1MHz Piezoelectric detection Corrugation : 0.3 Å 1nm x 1nm, 51 s 2nm x 2nm, 51 s 1nm x 1nm 13 s 2nm x 2nm, 13 s

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology Summary AT-cut QCR : High speed NSOM Tuning fork : High force sensitivity MFM, EFM Trident QCR : Atomic resolution AFM in air

Creative Research Initiatives Seoul National University Center for Near-field Atom-Photon Technology Thank you !!! Near field Group Researchers Yongho Seo, Ho Jin Cho, Moon Hun Hong, Jun Mo An, Sung Jin Jang, Hwan Sung Choi, Kyeong Ho Kim, Professor Wonho Jhe