Dynamic force microscopy and Kelvin probe force microscopy of KBr film on InSb() surface at submonolayer coverage

Kołodziej, Jacek; Such, Bartosz; Czuba, P.; Struski, P.; Piątkowski, P.; Szymoński, Marek

doi:10.1016/j.susc.2004.05.023

Cited by 29 publications

(25 citation statements)

References 8 publications

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“…The UHV KPFM microscope is a modified VP2 AFM/ STM Park Scientific Instruments device, 8 operating at a pressure of 5 ϫ 10 −11 mbar and at room temperature ͑RT͒. In the measurements, the topography was acquired using noncontact FM mode with a silicon ͑boron-doped͒ piezoresistive cantilevers purchased from Park Scientific Instruments.…”

Section: Methodsmentioning

confidence: 99%

“…7 Moreover, for some heterogeneous surfaces, by using KPFM, not only true topography is recorded but also the chemical contrast can be obtained. 8 From many crucial aspects concerning KPFM technique, the limits of potential sensitivity and lateral resolution are particularly important. Recently, lateral resolution on the atomic scale in the CPD signal has been reported 9,10 but its origin is still poorly understood, mainly due to the longrange nature of electrostatic forces.…”

Section: Introductionmentioning

confidence: 99%

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Lateral resolution and potential sensitivity in Kelvin probe force microscopy: Towards understanding of the sub-nanometer resolution

et al. 2008

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We report on high-resolution potential imaging of heterogeneous surfaces by means of Kelvin probe force microscopy, working in frequency modulation mode ͑FM-KPFM͒, performed in ultrahigh vacuum. To study the limits of potential and lateral resolutions in FM-KPFM, we have investigated clean surface of compound semiconductor InSb͑001͒ and the same surface with some submonolayer coverages of KBr and Au. It was found that long-and short-range bias-dependent interactions, acting between the tip and the surface, could be detected and that both interactions contribute to the measured contact potential difference ͑CPD͒ signal. On the one hand, when only the long-range electrostatic interactions between the tip and the surface are active, the CPD map provides the distribution of the local surface potential on the imaged sample with the lateral resolution and the correctness of the measured values depending on the measurement conditions. For this case, the experimental findings were compared with the predictions of theoretical calculations based on a realistic model for the cantilever-sample geometry. On the other hand, when the short-range and bias-dependent interactions are detected, FM-KPFM provides even the sub-nanometer contrast in the CPD signal. In this situation, however, the measured CPD signal is not related to the sample surface potential but reflects the properties of the front tip atom-surface atom interactions.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Lateral resolution and potential sensitivity in Kelvin probe force microscopy: Towards understanding of the sub-nanometer resolution

et al. 2008

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“…In a few experiments, even molecular 10 or atomic [11][12][13] contrast has been reported. The extension of the technique to insulating surfaces was performed more recently, as demonstrated by the results reported on thin ionic films on metals 14,15 or on the contribution of bulk defects to the surface charge state of ionic crystals. 16,17 In this work, atomic corrugation of the CPD signal is reported on the ͑001͒ surface of a bulk ionic crystal of KBr.…”

Section: Introductionmentioning

confidence: 99%

Analytical approach to the local contact potential difference on (001) ionic surfaces: Implications for Kelvin probe force microscopy

Bocquet

Nony²,

Loppacher³

et al. 2008

Phys. Rev. B

104

100

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An analytical model of the electrostatic force between the tip of a noncontact atomic force microscope ͑nc-AFM͒ and the ͑001͒ surface of an ionic crystal is reported. The model is able to account for the atomic contrast of the local contact potential difference ͑CPD͒ observed, while nc-AFM-based Kelvin probe force microscopy ͑KPFM͒ experiments. With the goal in mind to put in evidence this short-range electrostatic force, the Madelung potential arising at the surface of the ionic crystal is primarily derived. The expression of the force, which is deduced, can be split into two major contributions: the first stands for the coupling between the microscopic structure of the tip apex and the capacitor formed between the tip, the ionic crystal, and the counterelectrode and the second term depicts the influence of the Madelung surface potential on the mesoscopic part of the tip, independent of its microscopic structure. The former has the lateral periodicity of the Madelung surface potential, whereas the latter only acts as a static component, which shifts the total force. These short-range electrostatic forces are in the range of 10 pN. Beyond the dielectric properties of the crystal, a major effect, which is responsible for the atomic contrast of the KPFM signal, is the ionic polarization of the sample due to the influence of the tip/counterelectrode capacitor. When explicitly considering the crystal polarization, an analytical expression of the bias voltage to be applied on the tip to compensate for the local CPD, i.e., to cancel the short-range electrostatic force, is derived. The compensated CPD has the lateral periodicity of the Madelung surface potential. However, the strong dependence on the tip geometry, the applied modulation voltage, and the tip-sample distance, which can even lead to an overestimation of the real surface potential, makes quantitative KPFM measurements of the local CPD extremely difficult.

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“…Both scanning tunneling microscopy ͑STM͒ and noncontact atomic force microscopy ͑nc-AFM͒ measurements were performed at room temperature after the completion of the annealing process which lasted at least 10 h. For the nc-AFM and KPFM measurements a modified VP2 AFM/STM Park Scientific Instruments device equipped with Nanosurf "easy-PLL" demodulator was used. 20 The topography was acquired using noncontact frequency modulated ͑FM͒ mode with a silicon ͑boron-doped͒ piezoresistive cantilever, purchased from Park Scientific Instruments, of resonance frequency of about 200 kHz. The frequency shift relative to the free cantilever resonance frequency was set in the range of −10 to −50 Hz at a constant oscillation amplitude of 10-20 nm.…”

Section: Methodsmentioning

confidence: 99%

Scanning probe microscopy study of height-selected Ag/Ge(111) nanomesas driven by quantum size effects

et al. 2010

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We present scanning tunnel microscope, noncontact atomic force microscopy, Kelvin probe force microscopy, and low-energy electron diffraction study of the morphological evolution of Ag ultrathin films (0.5-6 ML) grown at 150 K on Ge(111)-c(2×8) substrate. Although the system has been widely studied in the context of quantum confinement effects in the electronic structure of these films, no real-space imaging has been reported so far. Our results demonstrate that upon annealing to room temperature, the Ag film adopts a (111) epitaxy on top of a wetting layer. It has been found that the Ag film adopts a metastable morphology which is determined by a delicate interplay between thermodynamics and the kinetics of interlayer mass transport. The preferential population of a discrete set of the deposit heights at 6, 10, and 12 ML suggests that quantum size effects are indeed active for the Ag/Ge system. Kelvin probe force microscopy indicates that the surface potential depends monotonically on the film thickness and does not show any oscillatory behavior in correspondence to the height change

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Dynamic force microscopy and Kelvin probe force microscopy of KBr film on InSb() surface at submonolayer coverage

Cited by 29 publications

References 8 publications

Lateral resolution and potential sensitivity in Kelvin probe force microscopy: Towards understanding of the sub-nanometer resolution

Lateral resolution and potential sensitivity in Kelvin probe force microscopy: Towards understanding of the sub-nanometer resolution

Analytical approach to the local contact potential difference on (001) ionic surfaces: Implications for Kelvin probe force microscopy

Scanning probe microscopy study of height-selected Ag/Ge(111) nanomesas driven by quantum size effects

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