Development Basic Principles of Advanced AFM Modes & Applications Dr. Stanislav Leesment,, NT-MDT 16th June 2014 Webinar Overview • • • • • • • • • • • • • AFM Operation: main principles Topography in Contact and Noncontact modes Phase Imaging High Resolution Choice of cantilever Spreading resistance imaging (conductive AFM/Current mapping) Kelvin Probe Microscopy (KPM) Piezoresponce Force Microscopy (PFM) M Magnetic ti Force F Mi Microscopy (MFM) Nanolithography Force Spectroscopy HybriD™ Mode Questions and Answers AFM Operation: Main Principles AFM: Scanning by Sample SAMPLE SCANNING AFM: Scanning by Tip TIP SCANNING Topography Imaging Imaging. Contact and Noncontact Modes. Contact Mode According the Hook’s law, law Force interaction between tip and the sample is proportional to tip bending and the cantilever stiffness. Stiffness for contact mode cantilevers can vary from 0 01 to several N/m 0,01 Contact-Mode Based Modes Noncontact (Semicontact, Tapping, AM-AFM) Mode AFM probe, b w=50 50 kH kHz, k = 00.5 5 N/ N/m, Q = 80, Rt =10 nm, A0 = 5 nm S. Belikov et al Fall 2012 MRS Proceedings, 2013 Phase Imaging Phase Imaging. Scan Examples. Name: Water on Mica Environment: Air Tip: NSG10 Size: 10x10 um Sample and Image Courtesy: Reinier Oropesa-Nuñez, CEAC, Cienfuegos, Cuba High-Resolution Imaging in AM-AFM in Air C18H38 Phase PTFE Height 18 nm 50 nm C122H246 Height C36H74 Phase 90 nm C242H486 Height C390H782 Height CnH2n+2 C18H38 2.8 nm C22H46 3.0 nm C36H74 4.5 nm C60H122 7.5 nm C122H246 15.0 nm C242H486 29.0 nm C390H782 49.0 nm C122H246 Height 135 nm 550 nm 750 nm 750 nm 4 of 35 Image Courtesy: Dr. S. Magonov, NT NT-MDT MDT Development Co. Tip Sharpness Limitation Z AFM line profile X 2 Probe tip 5 R=10 R 10 nm R=1 nm X axis direction Real object (e.g. (e g DNA molecule) 10 Probes for High Resolution Left: high-resolution AFM phase image of poly(dG)–poly(dG)– poly(dC) triplex DNA. The top graph shows a cross-section of the image along the white line (at the bottom part of the image). Right: histogram of distances between adjacent peaks on crosssections taken on many molecules (overall >200 values); the average distance is 3.4 nm (SD = 0.9 nm) D. Klinov, B. Dwir, E. Kapon, N. Borovok, T. Molotsky and A. Kotlyar. High-resolution atomic force microscopy of duplex and triplex DNA molecules. Nanotechnology 18 (2007), 225102. Cantilever Choice Cantilever Choice NT‐MDT AFM probes Semicontact / noncontact Semicontact / noncontact Contact (tapping) HA_C HA NC HA HR HA FM HA_NC, HA_HR, HA_FM CSG01, CSG10, CSG30 NSG01, NSG10, NSG30, NSG03 Conductive Pt TiN A Au Magnetic W MFM01, MFM10 MFM LM MFM_LM MFM_HC Electromagnetic Properties Spreading Resistance Imaging (SRI) Spreading Resistance imaging MDMO‐PPV and PCBM Blend Top left topography obtained in SSRM mode (-5V), top right – current mapping, bottom right current cross-section cross section profile. profile MDMO‐PPV and PCBM Blend Current maps with various bias voltage, -10 10 V -5 5V +1 V +5 V -1 1V +10 V Conductivity Map of OTS Sample Topography Current Current contrast of “Flowers” about 2 pA Sample Courtesy: Prof. Jacob Sagiv, Weizmann Institute of Science, Israel Probes for Spreading Resistance Probes for Spreading Resistance should normally have relatively small spring constant 0,05 – 1 N/m contact probes and good p g conductive coating g (PtIr, TiN, Au) 20 nm Kelvin Probe Force Microscopy (KPFM) Two-Pass KPFM KPFM on Carbon Nanotubes 3 3 2 2 1 1 Topography SKM image It should be noticed that SKM image reveals three kinds of nanotubes : 1)) Nanotubes with electric p potential about 1 V,, these nanotubes have smallest diameter ((about 1.5 nm)) 2) Nanotubes with electric potential about 0.5 V which have diameter about 2-3 nm 3) Thickest nanotubes which give smallest contrast in SKM and have biggest diameter (4 nm) Charge Lithography on GaAs Raster lithography on the GaAs substrate made with a diamond coated probe. Topography (left) and Kelvin mode (right) images. p g p y( ) ( g ) g Lithography is made by surface charging under the layer of GaAs oxide. Topography image shows nothing, when the right image made in SKM mode demonstrates areas charged positively and negatively on the neutral background. Single-Pass Electric Studies: EFM, KFM, dC/dZ, dC/dV Working frequencies: mech ≈ 70 kHz; elec = 3-5 kHz; 2nd Eigen mode (2E) ≈ 450kHz; 3rd Eigen (3E), etc KFM-AMnon-res dC/dZ-AMnon-res KFM-AMres dC/dZ-AMres – 2E, 3E KFM-PM KFM PMnon-res dC/dZ dC/dZ-PM PMnon-res Multi-Frequency Study of Electrical Properties Single-Pass and Double-Pass KFM of Fluoroalkanes on Mica C Comparison i off Si Single-Pass l P and dD Double-Pass bl P KFM Modes M d F14H20 on mica Probes for KPFM FMG01/Pt Resonance frequency ~60 60 kHz 20 nm Piezoresponce Force Microscopy (PFM) Piezoresponse Force Microscopy Topography PFM studies of TGS sample. • Cantilevers (40 N/m) with Pt coating were used for measurements • AC-sample mode with 10V@100kHz applied was used for PFM measurements. VPFM Amplitude 20 µm 20 µm VPFM Phase 20 µm Piezoresponse Force Microscopy Block scheme of PFM PFM: Non-Orthogonal Domains Hi h T High-Temperature Molecular M l l Ferroelectric F l i Crystal C l off Diisopropylammonium Dii l i Bromide B id (DIPAB) Amplitude, VPFM Topography Phase, VPFM PFM: 60V@100kH @ z 4 m 4 m 4 m Amplitude, LPFM DIPAB Phase, LPFM 426K b c DIPAB – courtesy Prof. P f T T. Usher U h (UC S San Bernardino) 4 m 4 m 35 Probes for PFM Probes for PFM should normally have high spring constants 1 – 100 N/m and coating with high conductivity (PtIr, TiN) 20 nm Magnetic Force Microscopy (MFM) MFM Principle Different magnetic domain structures of nonhomogenious Yttrium Iron Garnet (YIG) films. YIG film has substantial variation of anisotropy field along the film thickness Temperature Dependency Temperature control: -28 28...+300 +300°C C MFM images of the cobalt monocrystal with uniaxial anisotropy. Phase transition occurs when temperature increases. Images obtained from the same area, 14x40 μm. Sample courtesy of Prof. A.G. Pastushenkov, Tver University, Russia. Domain Structure Transformation in External Magnetic Field Changes of the domain structure of Au/Co/Au ...Co/Au sandwich structure. t t H = 0 Oe H = 1000 Oe Out-of-Plain External Magnet H = 500 Oe H = 1500 Oe In-Plain External Magnet MFM Probes MFM_LM – low moment tips Fig. 1. Fig 1 Topography (left) and Magnetic MFM (right) images of Self-Assembled particle array after Co/Pd thin film deposition. deposition Scan size 3x3 um. Sample Courtesy - Prof. Manfred Albrecht, Chemnitz University of Technology, Institute of Physics MFM_HC – high correcitivity tips Nanolithography Types of Nanolithography Vector lithography on OTS layer Modes: - Force - Voltage - Current Methods: - Vector - Raster Regimes: g - Constant - Gradient - Pulse - Pulse Gradient 3×2 ×4 = 24 Types! Force Lithography Voltage and Current Lithography Local Anodic Oxidation of Titanium film ilm Channel width ~20 nm Precise Closed-Loop Control Closed-loop OFF Closed-loop ON Voltage Raster Nanolithography 1 µm 2 µm Nanomanipulation Carbon nanotubes on silicon substrate. Manipulation p of nanotubes in the specified direction (before (left), after nanomanipulations (right)). Scan size: 2.6x2.6 µm Probes for Nanolithography Diamond Coated Conductive Probes (DCP Series) - DCP01 - DCP10 - DCP20 Probes with W2C, TiO, TiN and Pt coatings were also reported to be successfully used in nanolitho applications Scanning Force Spectroscopy (SFM) Atomic Force Spectroscopy Principle Mechanical Properties of the Sample Force Curves on Different Materials PDMS60 Standard Models for AFM PDMS8 PDMS8 Rubbery materials: PDMS8, PDMS60 and PDMS 130 Models: Hertz, Sneddon, JKR, DMT PDMS130 Work of Adhesion Macro Work of Adhesion AFM 13.9MPa 49 J/m2 32 J/m2 1.61MPa 1.74MPa 58 J/m2 52.2 J/m2 0.74MPa 0.66MPa 47–58 J/m2 42.1 J/m2 Polymer Material Elastic Modulus Macro Elastic Modulus AFM PDMS-8 13.4MPa PDMS-60 PDMS-130 Force Curves measured on PS/PBD D D PS PBD Z Z Force Curves on Melanoma Life Cell Images were obtained with use of colloidal probe CPC_SiO2-A HybriD Mode™ HybriD Mode™ mode: One Curve – Multiple Data In Hybrid y Mode™ the tip-sample p p distance is modulated accordingg to the qquasiharmonic law. Thus tip enters a force interaction with the sample thousands of times per second. Force-distance curve analysis enables maps of topographical, mechanical and electrical properties of the sample to be extracted with high spatial resolution. C Commonly l Hybrid H b id mode d gives i t topography, h adhesion dh i and d elasticity l ti it mapping i pictures i t PS-LDPE Blend T Topography h Scan Size: 3×3 µm Adh i Adhesion E Modulus M d l Polyethylene blobs on polystyrene spheres l t h E Modulus overlaid over topography HybriD Mode + Conductivity Mapping + Hybrid y mode™ was coupled p with spreading p g resistance imaging: g g a constant DC voltage was applied between the sample and conductive tip. Thus while getting a topography, adhesion and elasticity properties of the sample current going through the circle was recorded. Complex Study of CNT Topograpy Current Stiffness Scan size: 1×1 µm Image Courtesy: Sergey Zayats Sample Courtesy: Dr. Irma Kuljanishvili, Saint Louis University, Department of Physics Living Stem Cells Topography Modulus Map Post-Processing Capabilities Revolution Cartridge Revolution Cartridge Innovative Revolution Head Stiff Soft - safe and easy Cartridge replacement - no system tweaking required (Plug & Play) - high throughput operation MFM SKM - Change g methods with the same pprobes ~ 40 x less probe replacements Revolution Cartridge Find more information at: http://ntmdt.com/titanium http://ntmdt com/titanium Thank you for your attention! All the animations used in presentation can be downloaded at: h // http://www.ntmdt.com/spm-principles d / i i l
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