Application of the KolibriSensor® to combined atomic-resolution scanning tunneling microscopy and noncontact atomic-force microscopy imaging

Torbrügge, Stefan; Schaff, Oliver; Rychen, J.

doi:10.1116/1.3430544

Cited by 48 publications

(39 citation statements)

References 32 publications

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“…All LEED images shown are contrast-inverted, i.e., dark areas correspond to high intensity. STM is performed in a commercially available system (JT-STM/AFM with KolibriSensors [24], SPECS Surface Nano Analysis) at a temperature of 1.1 K providing stable measurement conditions and a significantly reduced lateral mobility of the molecules on the surfaces.…”

Section: Methodsmentioning

confidence: 99%

Growth of coronene on (100)- and (111)-surfaces of fcc-crystals

et al. 2015

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Section: Methodsmentioning

confidence: 99%

Growth of coronene on (100)- and (111)-surfaces of fcc-crystals

et al. 2015

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“…When comparing only the thermal force gradient noise for silicon cantilevers and quartz sensors (see Table I in Ref. 31), Si cantilevers appear to be superior by more than four orders of magnitude. However, we need to consider that Si cantilevers cannot be operated in the force gradient regime when the tip comes close enough to feel chemical bonding forces.…”

Section: Noise Comparison Between Large-amplitude (Si Cantileversmentioning

confidence: 99%

“…29 and 30) and at room temperature. 31 Therefore, it is instructive to analyze the success factors of these sensors for the purpose of further improving their performance. TABLE I. Geometrical parameters, stiffness k, and eigenfrequency f 0 of the quartz oscillators used.…”

Section: Introductionmentioning

confidence: 99%

Comparison of force sensors for atomic force microscopy based on quartz tuning forks and length-extensional resonators

et al. 2011

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The force sensor is key to the performance of atomic force microscopy (AFM). Nowadays, most atomic force microscopes use micromachined force sensors made from silicon, but piezoelectric quartz sensors are being applied at an increasing rate, mainly in vacuum. These self-sensing force sensors allow a relatively easy upgrade of a scanning tunneling microscope to a combined scanning tunneling/atomic force microscope. Two fundamentally different types of quartz sensors have achieved atomic resolution: the "needle sensor," which is based on a length-extensional resonator, and the "qPlus sensor," which is based on a tuning fork. Here, we calculate and measure the noise characteristics of these sensors. We find four noise sources: deflection detector noise, thermal noise, oscillator noise, and thermal drift noise. We calculate the effect of these noise sources as a factor of sensor stiffness, bandwidth, and oscillation amplitude. We find that for self-sensing quartz sensors, the deflection detector noise is independent of sensor stiffness, while the remaining three noise sources increase strongly with sensor stiffness. Deflection detector noise increases with bandwidth to the power of 1.5, while thermal noise and oscillator noise are proportional to the square root of the bandwidth. Thermal drift noise, however, is inversely proportional to bandwidth. The first three noise sources are inversely proportional to amplitude while thermal drift noise is independent of the amplitude. Thus, we show that the earlier finding that quoted an optimal signal-to-noise ratio for oscillation amplitudes similar to the range of the forces is still correct when considering all four frequency noise contributions. Finally, we suggest how the signal-to-noise ratio of the sensors can be improved further, we briefly discuss the challenges of mounting tips, and we compare the noise performance of self-sensing quartz sensors and optically detected Si cantilevers.

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“…These overlayers could be thick enough for hindering the electron tunneling process between the tip and surface [9]. In conventional STM experiments in UHV, this overlayer is generally removed by different treatments such as resistive heating for W tips [13], or by ion sputtering treatment for W and Pt tips [21]. But cleaning the tip becomes a real challenge for a small piece of W or Pt/Ir wire attached at the free end of a tuning fork prong.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of ultra-sharp tips from carbon fiber for scanning tunneling microscopy investigations of epitaxial graphene on 6H-SiC(0001) surface

Meza

Lubin

Thoyer

et al. 2015

Carbon

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A B S T R A C TThe fabrication of ultra-sharp tips from carbon fiber (CF), which are mounted on a qPlus probe for combined dynamic scanning tunneling microscopy (STM) and frequency modulation atomic force microscopy (FM-AFM) experiments, is reported. The carbon fiber tips were electrochemically etched in a KOH or NaOH solution, using different electronic devices. CF tips with an apex radius $10 nm, as deduced from the measured slopes of the Fowler-Nordheim plots (kR < 70 nm for k $ 6), were routinely obtained with a homemade electronic device that controls the intensity of the etching current. Then, these conductive CF tips were also characterized by imaging the 6H-SiC(0 0 0 1) surface covered by an epitaxial graphene layer in ultra-high vacuum (UHV). The lattice of the ð6 ffiffiffi 3 p Â 6 ffiffiffi 3 p Þ R30°r econstruction was regularly imaged by STM working either in non-oscillating mode or in dynamic mode, which also maps the variations of the force gradient. From these measurements with a constant mean-tunneling-current of 20 pA, it was found that the STM tip suffered variations of the tip/surface force gradient in between 8.25 and 16.50 N/m when it scanned the epitaxial graphene layer on the reconstructed 6H-SiC(0 0 0 1) surface.

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Application of the KolibriSensor® to combined atomic-resolution scanning tunneling microscopy and noncontact atomic-force microscopy imaging

Cited by 48 publications

References 32 publications

Growth of coronene on (100)- and (111)-surfaces of fcc-crystals

Growth of coronene on (100)- and (111)-surfaces of fcc-crystals

Comparison of force sensors for atomic force microscopy based on quartz tuning forks and length-extensional resonators

Fabrication of ultra-sharp tips from carbon fiber for scanning tunneling microscopy investigations of epitaxial graphene on 6H-SiC(0001) surface

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