UHV chamber: (a) side and (b) top view.
Image of (a) preparation chamber and (b) coolable manipulator.
Image of STM chamber.
Sample holder modified by thermo-rods.
Heating stage with sample (a) 3D view (b) side view.
Front view of multi-scale STM.
Front view of the two stages of the multi-scale STM: flexure scanning stage and beetle type stage.
Front view of beetle type STM.
Details of inner piezo that holds the tip.
Front view of flexure scanning stage based STM.
Eddy current damping.
Typical ECU architecture; PC: Personal computer, STM: Scanning tunneling microscope, ECU: Electronic control unit, PCI: Peripheral component interconnect bus, LAN: Local area network, PWR: Power supply, RT: Real-time controller, FPGA: Field-programmable gate array, HV-Amp: High-voltage amplifier, I/O: Input/output interface, DAC: Digital-to-analog converter, ADC: Analog-to-digital converter, CTRL: Control voltages for HV-amplifiers, VT: Bias voltage, R1..R2: Additional HV output channels, IN1…IN4: Signal input channels.
Software architecture; PC: Personal computer, STM: Scanning tunneling microscope, FPGA: Field-programmable gate array, CMD: Command task, DAQ: Data acquisition and communication task, UI: User interface, FIFO: First-in first-out buffer, PCI: Peripheral component interconnect bus, TCP/IP: Transmission control protocol/Internet protocol, SEND: Send task, RECV: Receive task, DAC: Digital-to-analog converter, ADC: Analog-to-digital converter.
Operating principle of the multi-scale STM (tunnel current amplifier not shown); LAN: Local area network, ECU: Electronic control unit, HV: High voltage, ITA: Tunnel current signal routed to ECU-A, ITB: Tunnel current signal routed to ECU-B, VZA: z-drive signal from ECU-A, VZB: z-drive signal from ECU-B, VTA: Bias voltage generated by ECU-A; signals contributing to the feedback process are shown as thick lines, others as thin lines.
Z-signals during scanning with flexure stage STM (a), (d) image based on z-signal of flexure stage (b), (e) image based on z-signal of beetle stage (c), (f) sum of (a), (d) and (b), (e).
Overview images of GaN based sample: (a) light microscope image. Circle marks a defect on the sample (b) multi-scale STM image recorded with flexure scanning stage showing large roughness on the surface; I = 0.15 nA, V = −3.8 V (c) flexure scanning stage based image resolving the micropillars; I = 0.15 nA, V = −3.8 V, image is smoothed by a 2 pixel Gaussian smooth (d) SEM image recorded ex situ.
Magnification series of star-shaped GaN based micropillars: (a) SEM image (b)–(g) STM images: (b)–(d) imaged by the flexure scanning stage based STM; I = 0.153 nA, V = −3.615 V. (e)–(g) imaged by beetle-type STM; I = 0.2 nA, V = −3.8 V.
Au(111) imaged by beetle-type STM stage: (a), (b) Step array for height calibration; I = 60 pA, V = 538 mV: (a) STM image (b) line scan across five steps (c)–(f) Reconstruction lines (d) line scan across domain walls along the line in (c) (f) line scan along a domain wall of the unfiltered image along the line in (e); I = 0.36 nA, V = 83 mV (a) and (c) are unfiltered images, (c) is filtered by a 2×2 pixel Gaussian.
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