Key Features

•SensitiveandFast•Reliable•Adjustment-Free•SimultaneousAFM&STM•NanoManipulation•AFMinLiquids•KelvinProbeMicroscopy

ADVANCEDQUARTZSENSORTECHNOLOGYFORFM-AFM

KolibriSensor

INNOVATIONINSURFACESPECTROSCOPYANDMICROSCOPYSYSTEMS

SPECS leads the way in state-of-the-art technology for electron spectroscopy and scanning probe microscopy.

SPECSSurfaceNanoAnalysisGmbH

SPECS headquarters with more than 150employeesislocatedinthecenterofGermany’scapital Berlin, with subsidiaries in Switzerland(SPECSZurichGmbH)andintheUSA(SPECSInc.).Furthermore, we have liaison offices in FranceandSpainandarerepresentedallovertheglobebyoursalespartners.

State-of-the-art scanning probe microscopy sytems

Weareateamofscientistsandengineerswhohavebeendedicating theirknowledgeandexperienceto the development, design, and productionof instruments for surface science, materialsresearch,andnanotechnologysince1983.

Ourkeytosuccesisknow-how,experience,closecontact to scientists from all over the world,customer orientation, reliable quality control,anddynamicresearchanddevelopment.

Schematic diagram of a mechanical oscillator as used as a force sensor in FM-AFM. The tip is part of the oscillating mass m.

m

k

tip

sample

ADVANCEDQUARTZSENSORTECHNOLOGYFORFM-AFM

Frequencymodulationatomicforcemicroscopy(FM-AFM)isapowerfulscanningprobetechniqueto image a large variety of surfaces on lengthscales ranging fromseveralmicrometers to theatomic scale using a tip as a probe. FM-AFMis based on the measurement of quantitiesrelated to tip-sample interaction forces.A mechanical oscillator - characterized by itsspringconstantk,eigenfrequencyf0,andqualityfactorQ-isusedasaforcesensor.Thetipispartoftheoscillatingmassm.

InFM-AFM,theforcesensorisdriventooscillatewithconstantamplitudeA;resonanceisimposedvia the phase relation between the excitationforce and the tip oscillation. The oscillationfrequency fof the forcesensordependson tip-sample forces. The basic measured quantity inFM-AFM is the frequency shift Δf of the forcesensor, defined as the difference between theoscillation frequency f with the tip subject tointeractionforcesandtheeigenfrequencyf0.

The mechanical tip oscillation is convertedto an electrical signal (deflection detection).The frequency shift is measured by frequencydemodulationwithaphase-lockedloop(PLL).

Frequency Modulation Atomic Force Microscopy

KolibriSensor

AdvancedQuartzSensorTechnologyforFM-AFMThe KolibriSensor combines great forcesensitivity with high acquisition speeds. It isself-actuating and self-sensing. It is compatiblewith powerful tip preparation techniques. Withits great simplicity andhigh reliability, it allowsthe researcher to focus on the experiment,not the force sensor. Fast. Symmetric. Lasting.AtrueKolibri.

The KolibriSensor is manufactured employing a sophisticated micro-fab-rication process. Individu-ally tested and specified, the KolibriSensor is a reliable plug-and-play SPM sensor with outstanding performance.

The KolibriSensor from SPECS is a quartz sensor for simultaneous FM-AFM and STM. It features excellent signal-to-noise ratio. It is simple to operate and reliable.

ADVANCEDQUARTZSENSORTECHNOLOGYFORFM-AFM

Spectral noise density of the force gradient ΔkTS in the free-oscillation regime measured at room temperature. A = 100 pm, Q = 27,000, k = 540 kN/m. The bandwidth of amplitude and phase loop was 50 Hz and 100 Hz, respectively.

0 200 400 600 800 10000.000

0.002

0.004

0.006

0. 000

0. 001

0. 002

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A = 100 pm

∆kTS S

pect

ral N

oise

Den

sity

((N

/m)/

√Hz)

Frequency (Hz)

∆f S

pect

ral N

oise

Den

sity

(Hz/

√Hz)

ΔkTS = 4 * Δf * k/fres

5

FM-AFM image of the Si(111) (7x7) surface acqui-red at room temperature with an Aarhus SPM. A = 200 pm, ∆f = -0.3 Hz, 5 nm x 5 nm, 256 x 256 Pixel

SmallerAmplitudes

Oscillationamplitudesmaybesetbelow20pm.The high spring constant of the KolibriSensorenables stable oscillation, the low-noisedeflectiondetectionagoodfrequencyshiftsignalevenat small amplitudes. Small amplitudesarefavorable forhigh-resolutionFM-AFMandareaprerequisiteforsimultaneousSTMandAFM.

HigherQFactor

The KolibriSensor is based on a symmetricallength extension resonator. The center ofmass remains at rest and reaction forces arecompensated inside the quartz with minimallosses. Very high Q factors, resulting in lowfrequency noise and high force sensitivity, areachievedindependentlyofthesensormount.

25s/frame

sensitive

TheKolibriSensoristhemostsensitivequartzbasedAFMsensor

HigherForceSensitivity

ThepiezoelectromechanicalcouplingconstantoftheKolibriSensorisabouttentimeshigherthanthat of typical quartz tuning forks, the 1 MHzresonance frequency of the KolibriSensor is onthe order of 30-50 times higher. This results ina remarkably low deflection noise floor of lessthan1fm/√HzwiththeexternalKolibriPreamp™.This key advantage of the KolibriSensor resultsin fasterdataacquisitionandhigher resolution.Evenwith itshighspringconstantof540kN/m,the KolibriSensor has a signal-to-noise ratio anorder of magnitude better than typical tuningfork setups whenmeasuring the force gradient(forthesameQfactorandoscillationamplitude).This surprising and experimentally verifiedresult is due to the KolibriSensor’s very strongdeflectionsignal.

KolibriSensor

Fast

FM-AFMimagingwasneverasfastaswiththeKolibriSensor

IncreasedScanningSpeed

The slow scanning speed achieved when usingtypical silicon cantilevers or tuning forks forUHV FM-AFM with acquisition times of severalminutesperframeisaseverelimitationinmanyapplications. The KolibriSensor with its highresonance frequency of 1 MHz and excellentsignal-to-noiseratioovercomesthislimitation.ItenablesfasterdataacquisitioninFM-AFMimagingand force spectroscopy. Atomic resolutionFM-AFM is now possible with unprecedentedacquisition times below one second per frame,evenoninsulatingsubstrates.TheKolibriSensorfacilitates rapid characterization of surfacetopography on large scales at astonishingscanningspeeds.

FM-AFM image of KBr(001) acquired at room temperature with an Aarhus SPM.Upper: 0.8 Sec./Frame, 1.5 nm x 1.5 nm , 64 x 64 Pixel, A = 100 pm, ∆f = +3.0 HzLower: 300 nm x 300 nm, 256 x 256 Pixel, A = 200 pm, ∆f = +0.6 Hz

50 seconds/frame100 seconds/frame

8 seconds/frame25 seconds/frame

0 seconds 4 seconds

Constant height images on Au(111) of the frequency shift Δf and the tunneling current It, acquired simul-taneously with a KolibriSensor and an Aarhus SPM at room temperature, A = 300 pm.

Constant current STM image of graphene on Ru(0001) acquired with a KolibriSensor with oscillating tip and an Aarhus SPM at room temperature. U = +0.7 V, Iset = 50 pA, A = 100 pm

Frequency shift, tunneling current and dissipation on Si(111) (7x7) acquired simultaneously as a function of bias at room temperature with an oscillation ampli-tude A = 300 pm.

7

accurate

FM-AFMandSTM–Simultaneous,andEachatitsBestWith small oscillation amplitudes, theKolibriSensor enables simultaneous STM andFM-AFM.Foracquisitionofthetunnelingcurrent,the KolibriSensor’smetal tip is providedwith aseparate electrical contact, which guaranteesclean separation of STM and AFM signals. TheKolibriSensor is also excellent for conventionalSTMwithnon-oscillatingtip.

Topographic FM-AFM images acquired in the short-range attractive and repulsive regime at room temperature with an Aarhus SPM.

Δf = +2.2 Hz, A = 100 pm

Au(111) Si(111) (7x7) KBr(001)

Δf = +0.44 Hz, A = 200 pm

Δf = +0.22 Hz, A = 200 pm

Δf = -0.37 Hz, A = 400 pm

Δf = -0.16 Hz, A = 300 pm

Δf = -0.50 Hz, A = 300 pm

KolibriSensor

FM-AFMatSmallDistances

With its extraordinary force sensitivity, the KolibriSensor is excellentfor high-quality atomic-resolution FM-AFM imaging on various surfacesincluding insulators. The sensor’s stable oscillation at small amplitudesenables imaging in both the short-range attractive (negative Δf) andrepulsive(positiveΔf)tip-sampleinteractionregime.

Characteristics of the frequency shift Δf and the dissipation in the free-oscillation regime as a function of scanner elongation z, acquired at room tempera-ture with a KolibriSensor mounted to the scanner of an Aarhus SPM. No dependence of the frequency shift and the dissipation, hence the sensor’s Q factor, on the scanner elongation is observed. f = 999175 Hz, Q = 27500, A = 100 pm

-25

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-5

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z Position Scan Piezo (nm)

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sipa

tion

(pW

)

Δf (m

Hz)

-150 -100 -50 0 50 100 150105.8

105.9

105.9

106.0

106.0

106.1

106.1

A = 100 pm

Characteristics of the tunneling current and the frequency shift on Si(111) (7x7) as a function of tip-sample distance acquired at room temperature with a KolibriSensor. U = 0.8 V, A = 300 pm

Tunneling Current forwardTunneling Current backwardFrequency Shift forwardFrequency Shift backward

Distance z (nm)

Tunn

elin

g Cu

rren

t (nA

)

Frequency Shift (Hz)

-1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

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9Spectroscopy

With its well defined electrical characteristics,the KolibriSensor is the ideal sensor forquantitative spectroscopy studies. What ismore, with its ability to simultaneously acquireforce and tunneling data, it is the ideal sensorforquantitativestudiesofrelationshipsbetweendifferent tip-sample interaction mechanisms.For instance, it is possible to simultaneouslymeasure the frequency shift, the dissipation,the tunneling current, and the differentialtunnelingconductance.

WellDefinedOscillation

The design of the KolibriSensor ensures anoscillation of the tip perfectly aligned withits longitudinal axis. In particular, there is notiltedoscillationas is typical forcantileversandsome tuning fork implementations. The directpiezoelectric excitation avoids excitation oflateral modes. Due to the symmetric layout ofthe quartz resonator, mechanical interactionsbetween the sensor oscillation and the sensormount are minimized. High Q factors arereproduciblyachievedindependentofthesensormountandelongationofascanner.

DissipationMeasurements

WiththeKolibriSensor,quantitativedissipationmeasurementsareeasyandaccurate.NocalibrationisnecessarysincethedissipatedpowerisdirectlyrelatedtotheunitsofVoltandAmpere.Dissipationofforcesensoroscillationenergyarises,whenthetip-sampleinteractionforceasafunctionofdistanceexhibitshysteresis.Dissipationprovidesvaluableinformationinmanycontexts.

Force map F(x,z) acquired on insulating KBr(001) along the line indicated in the inset. The measurement was done at room temperature with a KolibriSensor-equipped Aarhus SPM. Thermal drift was compensa-ted using the Nanonis Atom-Tracking module. A = 400 pm, total acquisition time 32 s

z po

sitio

n (n

m)

x position (nm)

Bias spectroscopy atop graphene and Ru(0001) surface sites measured at room temperature with an Aarhus SPM.

Topography (z) and local contact potential difference (UCPD) measured simultaneously by FM-KPFM on graphene grown on Ru(0001). Data acquired at room temperature with an Aarhus SPM.

Δf = -0.42 Hz, A = 500 pm,fmod= 65 Hz, Umod = 0.4 V, 550 nm x 550 nm, 0.25 lines /s

KolibriSensor

KelvinProbeForceMicroscopy

The local contact potential difference (CPD)relates to many surface phenomena, includingcatalytic activity, reconstruction of surfaces,and local charge distribution. The metallic tipof theKolibriSensormakes itan idealprobeformeasuring the local CPD by bias spectroscopyand frequency modulation Kelvin probe forcemicroscopy(FM-KPFM).

Versatile

TheKolibriSensorexcelsinvariousapplicationsofSPM

ForceMapping

Ideal for rapid acquisition of force-distancecharacteristics, the KolibriSensor is an excellentchoice formeasuring 2-D and 3-D force volumedata.

Surface of cleaved muscovite imaged in 1 M KCl buffer solution by FM-AFM with a KolibriSensor. Data acquired with an Aarhus SPM modified for imaging in liquids. A = 300 pm, Δfset = +140 Hz

Frequency response of a KolibriSensor with the tip oscillating in air (black) and in water (red), measured with an Aarhus SPM modified for imaging in liquids.

FM-AFM image of Si(111) (7x7), acquired at low temperature. T = 2.4 K, A = 69 pm, Q = 80,000, ∆f = -1.3 Hz. Courtesy of Toshu An, group of Prof. Hasegawa, The University of Tokyo.

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SPMinLiquids

TheKolibriSensor isprotectedbyasophisticatedmetal casing. The tip protrudes to the outsidethroughaholewith adiameterof only 100µm.The tipcanbe immersed inwaterwithoutwaterenteringthecasing,thesensor’sQfactorremainslarge.Sincesolelythetipisoscillatingintheliquidwhilethesensor’scasingandbaseareatrest,nospuriouspeaksarepresent.ThehighQfactorandexcellent noise floor below 1 fm/√Hzmakes theKolibriSensor an excellent force sensor for SPMin liquids. The KolibriSensor enables highest-resolutionFM-AFMinliquidswithunprecedentedeaseofuse.

LowTemperatureOperation

The adjustment-free, completely electronicself-sensing deflection detection makes theKolibriSensor ideal for low temperatureapplications where there is limited space,adjustment of optics would be complicatedor where complete darkness is important.The typical power dissipation of an oscillatingKolibriSensorisontheorderofPicowattsonly.

UpgradeyourSTMtoFM-AFM

The KolibriSensor features entirely electricexcitationanddeflectiondetectionbasedonthepiezoelectric properties of quartz. No externalactuatorsare required forexcitation.Deflectiondetection is adjustment-free. An excellentsignal-to-noise ratio is achieved with theexternal KolibriPreamp. Therefore, retrofittingexisting (low temperature) STM systems with aKolibriSensor for combinedSTMandFM-AFM isquickandeasy.

Scanning electron micro-graph of the KolibriSensor tungsten tip protruding from the sensor’s metal casing.

reliable

KolibriSensoriscommerciallyavailablewithguaranteedperformance

GuaranteedPerformance

The KolibriSensor’s high quality standard isachieved by employing a sophisticated micro-fabrication process, developed in collaborationwiththeSwisswatchmakingindustry.Eachsensoris tested at the factory. Resonance frequencyandQ factor are documented and provided onaspecificationsheet.

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KolibriSensor

Scanning electron micro-graphs of the same tip, before and after sputtering with a parallel oriented Ar+ ion beam (acceleration voltage 3.8 kV).

FIM image of a polycrystal-line KolibriSensor tungsten tip, measured at a tip bias of U = 3 kV with the tip held at room temperature.

PowerfulTipPreparation

The sensor’s metal casing enables simpleand powerful in-situ tip preparation andsharpening by parallel ion beam sputtering,field ion microscopy (FIM), field emission andevaporation. Parallel ion beam sputtering isan extremely powerful preparation techniquefor tungsten tips. It results in sharp, clean andoxide-free tips favorable for highest-resolutionSTMandFM-AFMimaging.Alsoblunttipsortipscontaminated after prolonged imaging on bulkinsulators or molecular films can be restoredby sputtering. As its tip canbe sputteredmanytimes,aKolibriSensorhasaverylonglife.

MetallicTipandMetallicShielding

The KolibriSensor is completely enclosed ina sophisticated metal casing, only the sharpetched tungsten tip protrudes outside througha tiny hole. The rugged casing not onlysimplifies handling. It provides electromagneticshielding, it limits crosstalk, it enables scanningcapacitance microscopy and powerful tippreparationtechniques.

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Spectral deflection noise density measured with the FEMTO HCA-2M-1M-C (red), a current-to-voltage converter, and the SPECS KolibriPreamp (black). Both measurements were conducted under identical condi-tions at room temperature with a KolibriSensor oscilla-ting at an amplitude of A = 10 pm and an Aarhus SPM.

KolibriSensor

KolibriPreamp

sPeCs KolibriPreamp™

HighestPerformanceDeflectionDetectionWith the new KolibriPreamp, the oscillationof the KolibriSensor can be detected withunprecedented precision. The noise floor isbelow 1fm/√Hz, one order of magnitude lowerthanachievedwithtraditionalcurrent-to-voltageconverter setups and lower than achievedwith even the best interferometric detectionsystems. With the KolibriPreamp, users of the

KolibriSensorcanobtain lower frequencynoise,enabling faster scanning speeds and smalleroscillation amplitudes. The KolibriPreamp wasdeveloped by FEMTO® Messtechnik GmbH andtakes advantage of their excellent know-howand experience with preamplifiers. Excellentcharacteristics are achieved also with relativelylongwiringdistancesbetweentheKolibriSensorand theKolibriPreamp’s input. InUHV systems,the KolibriPreamp is operated outside thevacuum chamber. The KolibriPreamp combineslowest-noisedeflectiondetectionwith thegreateaseofuseandreliabilityofexternalelectronics.TheKolibriPreampseamlesslyintegrateswiththeNanonisOscillationController.

KolibriPreamp Specifications

Bandwidth(-3dB) 250Hzto15MHz

Gain 0.7V/nm,10V/pC

NoiseFloor <1.0fm/√Hz

Max.OscillationAmplitude 7nm

Output/InputImpedance 50Ω/1GΩ@DC

SupplyVoltage/Current* ±15V/±100mA

PowerSupplyConnector* LEMO1S,3PinFixedSocket

*TheSPECSKolibriPreampisfullysupportedbytheNanonisOscillationController.

2.76

Ø9Ou

ter c

leara

nce

Ø2.5Cable clearance

Ø6

Top-view

15

Test stage with KolibriReceptor

KolibriReceptor

SPECS KolibriReceptor Specifications

Springs CuBe

Baseplate Al2O3

SpringContacts CuBeGoldplated

Weight 0.12g

Cables 3xcoppercoax,ø0.35mm,l=30cm

Kolibrisensor starter Kit

GettingStarted

SPECS provides a plug-and-play starter kitcomprising all components required to learnmoreaboutsensoroperationandhandling.

Thestarterkitcontains:

•ThreeKolibriSensors(native)•SPECSKolibriPreamp

•TeststagewithKolibriReceptor•SpecialtweezerstohandleKolibriSensors•Lownoisecablingfordirectconnectionof

theNanonisOscillationController

•Stand-aloneNanonisOscillationController

Kolibrireceptor™

PreciseKinematicMount

The KolibriReceptor is a precise kinematicmount with reliable electrical contacts for theKolibriSensor.ItisfullyUHV,lowtemperature,andhighmagneticfieldcompatible,andcanbedirectlyused as a building block in advanced scanningprobemicroscopedesigns.Thelightweightdesignallowsdirectmountingtoascanner.Thesnap-inmechanism allows inserting and removing thesensorwithawobblestickorevenwiththecoarsepositioningsystemoftheSPM.

Sensor weight: 0.4 gScrew socket material/height: Al2O3/0.635 mm

Ø123

2

1Top-view

Ø2.2Ø4.5

Ground contact (4)on backside

KolibriSensor

Bruker Adapter with KolibriReceptor fitting the Bruker MultiMode SPM head. Cable: 3x copper coax, ø 0.35mm

Kolibrisensors in Various Forms

KolibriSensorisavailableinvariousadaptationsfordifferentsystems

KolibriSensorBrukerAdapterKit

SPECSprovidesaplug-and-playkitcomprisingallcomponentsneededtostartimagingwithBrukerMultiMode®SPMs.

Thekitincludes:

•ThreeKolibriSensors(Native)•SPECSKolibriPreamp

•BrukerAdapterwithKolibriReceptor•SpecialtweezerstohandleKolibriSensors•Lownoisecablingfordirectconnectionofthe

NanonisOscillationController

ScrewmountKolibriSensor

The Screwmount option provides a convenientwayformountingandelectricallycontactingtheKolibriSensorbymeansofthreescrews(M1.6).

Sensor weight: 0.2 gClamp socket material: Stainless steelCable: 2x copper twisted pair

Sensor weight: 0.4 gHandle plate material/height: Al2O3/0.635 mm

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KolibriSensorforAarhusSPM

The KolibriSensor for the SPECS Aarhus SPMfeatures a socket for clamp insertion. Directcablingtothesensorisprovided.

KolibriSensorforTyto™SPM

The KolibriSensor for the SPECS Tyto SPM isdesignedformanipulationwithawobblestick.

Sensor weight: 0.11 gSubstrate material/height: Al2O3/0.4 mmCap material: TitaniumSensor without casing on request

KolibriSensor

SPECS KolibriSensor Specifications

ResonanceFrequency 1MHz

QFactor 10,000–100,000

TipMaterial/Weight Tungsten/1µg

SpringConstant 540kN/m

PiezoCoupling 65µC/m

NoiseFloor <1fm/√Hz

TypicalOscillationAmplitude 100pm

NativeKolibriSensor

sample

A

1: Uexc 2: Iosc

3: Itunnel

casing

oscillatingquartz rod

4

wire

metallic tip

1mm

PLL: Nanonis OC

Output: Excitation

Input: Oscillation

Tunneling Current

Any STM Preamp

SPECS KolibriPreampQuartz oscillator

Tip

19

Schematic Drawing

Equivalent Circuit

Recommended Instrumentation

NanonisOscillationControllerfortheFinestControloftheKolibriSensorThe Nanonis Oscillation Controller providesa convenient and proven way to drive theKolibriSensor. It affords both high-stabilityamplitude control and low-noise frequencydemodulationinasingledevicefullyintegratingwith the Nanonis SPM Control System.TheNanonisOscillationControllerfeaturesultra-low input noise, extreme frequency stabilityand highest frequency resolution essentialto take full advantage of the KolibriSensor.The control parameters for amplitude controlandfrequencydemodulationareuseraccessibleand can be auto-tuned using the uniqueperfectPLL™algorithm.

CompleteSPMSolutionsfromSPECS

For complete high-performance SPM solutionsincorporating KolibriSensor technology pleaserefer to our separate brochures on the provenAarhus SPM family offering extreme stability,speed, and highest productivity on a dailybasis inthetemperaturerangeof90Kto400K(1300 K optional), or the revolutionary SPECSultra-low temperature microscope JT-SPMwith lowest cryoliquid consumption foratomic manipulation and highest-resolutionspectroscopy at temperatures down to below1 K with 4He (below 500mKwith 3He optional)andoptionallyinmagneticfieldsupto3T.

sPeCsSurfaceNanoAnalysisGmbHVoltastrasse513355Berlin / Germanywww.specs.com

T+4930467824-0F+49304642083Einfo@specs.com