ASC500 Fully Digital Scanning Probe Microscope Controller

Transcription

1 ATTOCONTROL Electronic & Software Control Units ATTOCONTROL Electronic & Software Control Units ASC500 Fully Digital Scanning Probe Microscope Controller 2010, attocube systems AG - Germany. attocube systems and the logo are trademarks of attocube systems AG. Registered and/or otherwise protected in various countries where attocube systems products are sold or distributed. Other brands and names are the property of their respective owners. attocube systems AG Königinstrasse 11a (Rgb) D München Germany Tel.: Fax: info@attocube.com Brochure version: pioneers of precision pioneers of precision

2 01 ASC500 FULLY DIGITAL, FPGA-BASED SPM CONTROLLER The ASC500 is a modular and flexible digital SPM controller which combines state-of-the-art hardware with innovative software architecture, offering superior performance and an unprecedented variety of control concepts. The ASC500 controller was developed with the goal to never be the limiting factor in any SPM experiment. All desirable functions and high-end specifications for conducting the measurement of your choice in MFM, SHPM, AFM, CFM, SNOM, STM, and many other SPM experiments are available. With the dawn of Scanning Probe Microscopy (SPM) due to the invention of the Scanning Tunneling Microscope in 1983, SPM techniques have become some of the most important laboratory tools for studying surface phenomena on the nanometer scale. While the performance of room-temperature Scanning Probe Microscopes has evolved rather quickly, researchers have long kept looking for the ideal SPM control unit, providing an "open architecture" and maximum data handling flexibility for all available signals. With attocube's fully digital SPM controller - the ASC500 - new standards and benchmarks are set, enabling ultra-flexible high-performance SPM experiments. The ASC500 enables fast low-noise data acquisition with unmatched data processing capabilities for the most advanced applications and modes. Multiple inputs and outputs grant immediate access to every SPM signal, providing the researcher with the necessary experimental flexibility. Owing to its multifunctionality, high resolution and low noise performance, the ASC500 has become one of the most powerful SPM controllers currently available. STATE-OF-THE-ART CONTROLLER (ASC500) HIGH SPEED Powerful Highly flexible Fully digital Highest resolution Digital I/O: 8 inputs 8 outputs 40 MHz Analog inputs: 6 converters 400 khz 18 bit Analog outputs: 4 converters 200 khz 16 bit 2 analog modulation inputs Scan outputs: 3 converters 5 MHz in xy; highest resolution, z modulation input High frequency section: 2 independent HF channels with each: 50 MHz 16 bit input 50 MHz 16 bit output Sync output Preamplified signal monitor Auxiliary power: +/- 5 V +/- 15 V

3 02 OUTSTANDING FEATURES OFFERING SUPERIOR PERFORMANCE Scan Engine: The ASC500 uses a dedicated hardware with a 5 MHz scan generator, creating the scan voltages necessary for any Scanning Probe Microscope. The 16 bits of the xy outputs are always automatically mapped to the actual scan field, yielding a virtually unlimited bit resolution. Q Control The ASC500 provides full control over the Q factor of any driven lever system by means of electronic Q control. The natural Q factor of the lever can be varied by typically more than one order of magnitude in each direction (increase/ decrease). LabVIEW control The new LabVIEW interface provides full control over all ASC500 functions. Benefits are: measurement automation, user definable experiments, and easy implementation of 3 rd party instrumentation. Data Processing The collection of data is the most important task in every experiment. The ASC500 was built to give the user every possibility to view, process and save all data streams. Data can be visualized in 1D, 2D or 3D displays. Furthermore, the ASC500 features: - real-time FFT calculation and background filtering - full control over all raw and processed data - global Snapshot functionality: a user definable collection of data can be saved with only one mouse click - save parameters in a text file Measurement Modes STM: constant height, constant current AFM: contact mode, amplitude modulation, frequency modulation, PLL, Kelvin Probe, SGM MFM: constant height, dual pass mode SHPM: STM-tracking mode, constant height, and dual pass mode Z controller: The z scanner output is controlled by a digital PI algorithm with a bandwidth of 50 khz. The z output DAC has a resolution of 18 bit, yielding a 4 pm resolution on a 1 µm scan range. This resolution can be increased to a theoretical value of 60 attometer by limiting the control range. PLL A fully digital phase locked loop is implemented into the ASC500, taking advantage of the high frequency inputs/ outputs with 50 MHz bandwidth. A high-speed Lock-in demodulator and two PI control loops are used to control the amplitude of an oscillator and to follow any shifts in resonance. The frequency resolution is below 0.2 µhz in a range from 1 khz up to 2 MHz. Are you missing the sensitive adjustment possibilities provided by former analog SPM-units? Every ASC500 can be equipped with the ASC-iBox unit allowing fast and controlled manual adjustment of all major parameters. ibox This optional input box enables fast and controlled manual adjustment of scan and feedback parameters in addition to software adjustment capabilities. This allows a very intuitive way of controlling a parameter-sensitive experiment. - unique in the field of Scanning Probe Microscopy - control of important feedback parameters (P/I gain, z-offset) - control of setpoint and bias - adjustment of slope correction and rotation Spectroscopy The ASC500 features advanced spectroscopy techniques such as DOS-, Kelvin-Probe-, Force-distance-, and z spectroscopy. These measurements are supported by an internal Lock-in (e.g. for di/dv spectroscopy) and a limiter functionality which drastically reduces the likelihood of a tip crash. Spectroscopy measurements can be automatically triggered on line, grid or point-by-point paths. Combinations of spectroscopies can be defined in action lists. Digital/analog converters (DAC/ADC) The input and output capabilities of the ASC500 are outstanding. Its analog-digital converters use state-of-the-art hardware with lowest possible noise. On-board preamplifiers and switchable low-pass filtering allow for maximum signalto-noise ratios. Additional features include: - oversampling and offset compensation - analog modulation inputs for the most important channels - 6 ADC inputs with 400 ks/s, 18bit - 2 high frequency ADC inputs with 50 MS/s, 16bit - 4 DAC outputs with 200kS/s, 16bit - software defineable transfer functions

4 03 Details Specifications Interface xy scan voltage output 2 x V, 16 (+16) bit 5 MHz with programmable tilt correction, uni-/bipolar, output limiter, slewrate control z voltage output analog ADC inputs analog DAC outputs analog modulation inputs high frequency section general purpose digital interface digital interface (RS232) digital serial interface (NSL) host computer interface V, 18 (+16) bit, 200 ks/s, uni-/bipolar, output limiter, slewrate control 6 x V, 18 bit 400 ks/s ADC with prog. offset and gain compensation 4 x V, 16 bit 200 ks/s DAC switchable 2nd order low pass 3 khz / 100 khz; noise: 16 µvrms (10 Hz khz) V, DC.. 50 khz for DAC 1, DAC 2, and Z-Out 2 x 16 bit, 50 MS/s ADC /w cont. sig. amp. 2 x monitor output of preamplified signal 2 x 16 bit, 50 MS/s DDS-DAC, oscill. exc 2 x SYNC output with fixed 10 V amplitude 8 bit LVTTL trigger intput; 8 bit LVTTL trigger output; for optional prog. in / out sync, counter e.g. pixel-, line-, frame-clock connection to ANC300, for coarse movement connection to ANC350, for closed loop coarse movement USB 2.0 high speed, LAN 100 Mbit auxiliary power outlet +/-5 V (0.2 A) and +/-15 V (0.1 A) out- and input connector Scan Generation generation bandwidth 5 MHz pixel frequency resolution features scan speed/frame rate front side BNC sockets for all analog signals; 9 pin D-Sub for LVTTL lines 16 bit auto projected on scan area hardware rotation & zoom, slew-rate controlled movement, slope compensation, switchable uni-/bipolar 1 pm/s - 2mm/s, x100 px z Controller type digital PI, anti wind-up resolution bandwidth control signal features 18 bit, up to 34 bit for small control range 50 khz any internal data channel Phase Locked Loop (PLL) features 2 P/I controllers with graphical interface frequency resolution external modulation input, setpoint modulation, invertable feedback gain and output polarity, P/I gains in physical units 0.14 µhz frequency range 1 khz - 2 MHz Q Control type electronic, phase controlled efficiency decrease or increase of Q by factor 10 typ. Frame View display modes 2 frame views, 2 line views, easy creation of additional frames when needed options selection tools oversampling, autosave (png, ASCII, bcrf), line subtraction; line view with up to 16 subsequent lines frame alignment, frame centering, zoom function, path mode, grid mode Spectroscopy physical arrangement point/line/grid spectroscopy (up to 1024 x 1024 pixel) spectroscopy types averaging parameters Lock-in low frequency Lock-in 1 mhz - 20 khz modulation demodulation integration time purpose high frequency Lock-in integration time purpose z-spectroscopy, bias spectroscopy, soft spectroscopy (all gui parameters), di/dv with internal Lock-in 25 µs up to 160 ms per data point control loop off, signal limiter all DAC channels any internal signal up to 128 periods spectroscopy, vibrational analysis, Hall probe etc. 1 khz - 2 MHz up to 512 periods AFM cantilever signal, tuning fork signal etc. Second Pass Mode working principal 2 nd pass with height offset or different scan parameter set parameters application height offset, wait time, slew rate alternative DAC, alternative setpoint MFM, SGM Visualization oscilloscope arbitrary channel vs. time; time base 2.5 µs ms, pixel max. Trigger: amp/edge/auto/single FFT Path Mode working principle action executed along user defined path action list for every channel, khz range, x averaging, windowing options, scaling: magnitude/power density/power spectrum user definable, spectroscopies, manual handshake, TTL handshake Transfer Functions functionality ADC/DAC offset adjustment, linear transfer function programming, preamp for each ADC channel (1-64 x gain) Crosslink functionality two generic P/I loops, input/ouput for all ADC/DAC channels, map internal channel to arbitrary output channel

5 04 Overview of available microscopes Confocal Microscopes Confocal Raman Microscopes Scanning Near-Field Optical Microscopes Magnetic Force Microscopes Scanning Hall Probe Microscopes Atomic Force Microscopes Scanning Tunneling Microscope Cryogenic Probe Stations attodry1000 attodry1100 attodry2000 attocfm I attocfm II attocfm III attoraman attosnom III attomfm I attoshpm attoafm I attoafm III attoafm/stm attoafm/cfm attostm I attocps I attocps II on request on request on request attodry3000 on request on request on request on request attodry4000 on request attodry5000 on request on request attodry700 on request on request on request on request attodry500 on request on request on request on request on request attoliquid1000 attoliquid2000 attoliquid3000 on request on request attoliquid5000 on request on request on request on request on request on request attloliquid500 on request on request Description confocal highly modular and flexible, free-beam optics confocal highly stable and compact, fiber based confocal optimized for transmission measurements, fiber based confocal Raman developed for highest detection efficiency and stability fiber based, low temperature scanning near-field optical tuning fork based magnetic force cantilever based scanning Hall probe microscope atomic force cantilever based atomic force tuning fork based combined low temperature atomic force and scanning tunneling tuning fork based combined low temperature atomic force and confocal tuning fork based scanning tunneling highly compact and stable cryogenic probe station with four ultra stable nanomanipulation stacks highly flexible cryogenic probe station with four ultra stable nanomanipulation stacks

6 05 ASC500 SPM CONTROLLER application examples 06 ATTOCUBE SYSTEMS Creating scientific impact 500 nm Control of tuning fork AFM using internal PLL The internal PLL of the ASC500 was used to control a high Q tuning fork AFM. Topography measurements were performed on uncapped, stacked InAs Quantum Dots in a GaAs matrix. The evaluation of the height distribution revealed atomic steps with a spacing of 2 Ångstrom. Topography and error signal were recorded simultaneously (left and right image). 25 nm 500 nm 2.5 µm Q enhanced MFM vortex imaging A cantilever based MFM was used to image single vortices in BSCCO. The signal quality could be significantly enhanced by using the Q control functionality of the ASC500. The Q factor of the MFM lever was increased by a factor of 4 to record this image. For nonflat surfaces, dual pass mode can be employed for highest magnetic resolution. STM vortex imaging and di/dv spectroscopy A combined AFM/STM instrument was operated in an experiment at 300 mk and 1 T vertical magnetic field. Magnetic vortices on NbSe 2 were recorded in STM topography mode at a bias voltage close to the coherence peaks (1.4 mv). The superconducting gap spectrum (right image) was obtained using the internal Lock-in of the ASC500 (attocube application labs, 2009). CFM imaging using step scan function The ASC500 provides a step scan function to gain unlimited scan range at s. The above image was taken using a confocal microscope on a test grating. The raster motion was achieved by single step coarse movement of xy positioners. The ASC500 controls the coarse movement and synchronizes data collection. The ANC250 is a dedicated, ultra low noise scan voltage amplifier for piezo scanning tubes and flexure scanners. With an output noise of 20 µv a 500 khz bandwidth, the ANC250 offers the lowest noise specs on the market. Its three input channels drive five output channels with an amplification of +/- 20. The output voltages (x+, x-, y+, y-,z) of up to +/- 200 V are ideally suited to drive piezo tube scanners. S. Gröblacher, J. B. Hertzberg, M. R. Vanner, G. D. Cole, S. Gigan, K. C. Schwab, M. Aspelmeyer Demonstration of an ultracold micro-optomechanical oscillator in a cryogenic cavity Nature Physics 5, (2009). B.D. Gerardot, D. Brunner, P.A. Dalgarno, P. Öhberg, S. Seidl, M. Kroner, K. Karrai, N.G. Stoltz, P.M. Petroff, R.J. Warburton Optical pumping of a single hole spin in a quantum dot Nature 451, (2008). M. Kroner, A.O. Govorov, S. Remi, B. Biedermann, S. Seidl, A. Badolato. P.M. Petroff, W. Zhang, R. Barbour, B.D. Gerardot, R.J. Warburton, K. Karrai The nonlinear Fano effect Nature 451, (2008). M. Kroner, C. Lux, S. Seidl, A.W. Holleitner, K. Karrai, A. Badolato, P.M. Petroff, R.J. Warburton Rabi splitting and ac-stark shift of a charged exciton Appl. Phys. Lett. 92, (2008). M. Ediger, G. Bester, A. Badolato, P.M. Petroff, K. Karrai, A. Zunger, R.J. Warburton Peculiar many-body effects revealed in the spectroscopy of highly charged quantum dots Nature Physics 3, (2007). B.D. Gerardot, S.Seidl, P.A. Dalgarno, R.J. Warburton, M. Kroner, K. Karrai, A. Badolato, P.M. Petroff Contrast in transmission spectroscopy of a single quantum dot Appl. Phys. Lett. 90, (2007). I. Favero, C. Metzger, S. Camerer, D. König, H. Lorenz, J.P. Kotthaus, K. Karrai Optical cooling of a micromirror of wavelength size Appl. Phys. Lett. 90, (2007). B.D. Gerardot, S.Seidl, P.A. Dalgarno, R.J. Warburton, D. Granados, J.M. Garcia, K. Kowalik, O. Krebs Manipulating exciton fine structure in quantum dots with a lateral electric field Appl. Phys. Lett. 90, (2007). A. Babiñski, G. Ortner, S.Raymond, M. Potemski, M. Bayer, W.Sheng, P.Hawrylak, Z.Wasilewski, S.Fafard, A. Forchel Ground-state emission from a single InAs/GaAs quantum dot structure in ultrahigh magnetic fields Phys. Rev. B 74, (2006). M. Atatüre, J. Dreiser, A. Badolato, A. Högele, K. Karrai, A. Imamoglu Quantum-Dot Spin-State Preparation with Near-Unity Fidelity Science, 312(5773), 551 (2006). A. Högele, S. Seidl, M. Kroner, K. Karrai, M. Atatüre, J. Dreiser, A. Imamoglu, R. J. Warburton, B. D. Gerardot, P. M. Petroff Spin-selective optical absorption of singly charged excitons in a quantum dot Appl. Phys. Lett., 86, (2005). M. Kroutvar, Y. Ducommun, D. Heiss, M. Bichler, D. Schuh, G. Abstreiter, J. Finley Optically programmable electron spin memory using semiconductor quantum dots Nature, 432, 81 (2004). K. Karrai, R.J. Warburton, C. Schulhauser, A. Högele, B. Urbaszek, E. J. McGhee, A. O. Govorov, J. M. Garcia, B. D. Gerardot, P. M. Petroff Hybridization of electronic states in quantum dots through photon emission Nature, 247, 135 (2004). A. Högele, S. Seidl, M. Kroner, K. Karrai, R. J. Warburton, B. D. Gerardot, P. M. Petroff Voltage-Controlled Optics of a Quantum Dot Phys. Rev. Lett., 93, (2004). A. Babinski, S. Awirothananon, J. Lapointe, Z. Wasilewski, S. Raymond, M. Potemski Single-Dot Spectroscopy in High Magnetic Fields Physica E, 22, 603 (2004). R. J. Warburton, C. Schäflein, D. Haft, F. Bickel, A. Lorke, K. Karrai, J. M. Garcia, W. Schoenfeld, P. M. Petroff Optical emission from a charge-tunable quantum ring Nature 405, 926 (2000).