Tip geometry effects in scanning capacitance microscopy on GaAs Schottky and metal-oxide-semiconductor-type junctions

Eckhardt, Christian; Brezna, W.; Bethge, Ole; Bertagnolli, E.; Smoliner, J.

doi:10.1063/1.3140613

Cited by 19 publications

(13 citation statements)

References 20 publications

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“…The resolution of the method is determined by the shape and near-surface extension of the region charge carriers can be collected from. Simulations [7] show that for GaAs this is in the order of 50nm, depending on sample doping and surface states. For our sample, the dots appear to be around 50 nm in size, confirming that our resolution is at least 50 nm or better.…”

Section: Discussionmentioning

confidence: 95%

AFM‐based photocurrent imaging of epitaxial and colloidal QDs

Madl

Brezna

Strasser

et al. 2011

Phys. Status Solidi (c)

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We present photocurrent images and spectroscopic results of sub‐surface InAs quantum dots (QDs) and thin films of colloidal PbS QDs obtained at room temperature and under ambient conditions by means of photoconductive atomic force microscopy (pcAFM) under 916 nm and 900 nm illumination respectively. InAs QDs appear as dark areas in the photocurrent image, because imaging was performed at the wetting layer excitation energy. The PbS nanocrystal film imaged at the energy of the first excitonic transition displays local variations of the photoactivity. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Discussionmentioning

confidence: 95%

AFM‐based photocurrent imaging of epitaxial and colloidal QDs

Madl

Brezna

Strasser

et al. 2011

Phys. Status Solidi (c)

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“…For all measurements, a modulation voltage of 350 mV and an integration time of 12 s per capacitance value were used. [19][20][21] …”

Section: E Capacitance Bridge Measurementsmentioning

confidence: 98%

Calibrated nanoscale capacitance measurements using a scanning microwave microscope

Huber¹,

Moertelmaier

Wallis

et al. 2010

Review of Scientific Instruments

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136

105

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A scanning microwave microscope (SMM) for spatially resolved capacitance measurements in the attofarad-to-femtofarad regime is presented. The system is based on the combination of an atomic force microscope (AFM) and a performance network analyzer (PNA). For the determination of absolute capacitance values from PNA reflection amplitudes, a calibration sample of conductive gold pads of various sizes on a SiO(2) staircase structure was used. The thickness of the dielectric SiO(2) staircase ranged from 10 to 200 nm. The quantitative capacitance values determined from the PNA reflection amplitude were compared to control measurements using an external capacitance bridge. Depending on the area of the gold top electrode and the SiO(2) step height, the corresponding capacitance values, as measured with the SMM, ranged from 0.1 to 22 fF at a noise level of ~2 aF and a relative accuracy of 20%. The sample capacitance could be modeled to a good degree as idealized parallel plates with the SiO(2) dielectric sandwiched in between. The cantilever/sample stray capacitance was measured by lifting the tip away from the surface. By bringing the AFM tip into direct contact with the SiO(2) staircase structure, the electrical footprint of the tip was determined, resulting in an effective tip radius of ~60 nm and a tip-sample capacitance of ~20 aF at the smallest dielectric thickness.

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“…13 The total oxide charge density ͑2 ϫ 10 13 cm −2 Ϯ 0.2ϫ 10 13 cm −2 ͒ was determined from the shift of the flatband voltage with respect to the expected position. 13 The total oxide charge density ͑2 ϫ 10 13 cm −2 Ϯ 0.2ϫ 10 13 cm −2 ͒ was determined from the shift of the flatband voltage with respect to the expected position.…”

Section: Resultsmentioning

confidence: 99%

“…12,13 For quantitative SCS, an ultrahigh precision, variable frequency ͑50 Hz-20 kHz͒ capacitance bridge ͑Andeen Hagerling AH2700A͒ was attached to the AFM.…”

Section: Methodsmentioning

confidence: 99%

Frequency dependent capacitance spectroscopy using conductive diamond tips on GaAs/Al2O3 junctions

Eckhardt

Sousa

Brezna

et al. 2010

Journal of Applied Physics

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In this work, an unusual low frequency behavior observed in scanning capacitance microscopy/spectroscopy on GaAs/Al2O3 junctions is investigated. Using a two-dimensional simulation, we show that the frequency behavior of the capacitance—voltage curves can be explained through an increased minority carrier concentration at to the GaAs–Al2O3 interface and tip geometry effects on the nanoscale. An analytic approach to estimate the transition frequency between the low frequency and high frequency regime is also given.

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Tip geometry effects in scanning capacitance microscopy on GaAs Schottky and metal-oxide-semiconductor-type junctions

Abstract: Surface and interface properties of In 0.8 Ga 0.2 As metal-insulator-semiconductor structures

Cited by 19 publications

References 20 publications

AFM‐based photocurrent imaging of epitaxial and colloidal QDs

AFM‐based photocurrent imaging of epitaxial and colloidal QDs

Calibrated nanoscale capacitance measurements using a scanning microwave microscope

Frequency dependent capacitance spectroscopy using conductive diamond tips on GaAs/Al2O3 junctions

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