Georg Gramse

• MS; PhD
• PostDoc Position at Johannes Kepler University of Linz

The accelerated demand for electrochemical energy storage urges the need for new, sustainable, and lightweight materials able to store high energy densities rapidly and efficiently. Development of these functional materials requires specialized techniques that can provide a close insight into the electrochemical properties at the nanoscale. For thi...

The accelerated demand for electrochemical energy storage urges the need for new, sustainable, stable and lightweight materials able to store high energy densities rapidly and efficiently. Development of these functional materials requires specialized techniques that can provide a close insight into the electrochemical properties at the nanoscale....

In this paper, a definition of the gain and added noise of impedance matching networks for scanning microwave microscopy is given. This definition can be used to compare different impedance matching techniques independently of the instrument used to measure the S-parameter. As a demonstration, impedance matching devices consisting of a Beatty line,...

Quality control is highly relevant for safety, sustainability and efficiency of the battery manufacturing process. An early and reliable detection of failures in the production chain is important. Here we present a method for detecting micrometric imperfections and contaminations on the battery separator before filling the battery stack with the el...

In this paper, a definition of the gain and added noise of impedance matching networks for scanning microwave microscopy is given. This definition can be used to compare different impedance matching techniques independently of the instrument used to measure the S-parameter. As a demonstration, impedance matching devices consisting of a Beatty line,...

We outline calibrated measurements of the microwave reflection coefficient from the tunnel junction of an ultra-high vacuum low temperature scanning tunneling microscope. The microwave circuit design is described in detail, including an interferometer for an enhanced signal-to-noise ratio and a demodulation scheme for lock-in detection. A quantitat...

We outline calibrated measurements of the microwave reflection coefficient from the tunnel junction of an ultra-high vacuum low temperature scanning tunneling microscope. The microwave circuit design, including an interferometer set-up for enhanced signal-to-noise and a demodulation scheme for lock-in detection, is described in detail. A quantitati...

We show how microwave microscopy can be used to probe local charge transfer reactions with unprecedented sensitivity, visualizing surface reactions with only a few hundred molecules involved. While microwaves are too fast under classical conditions to interact and sense electrochemical processes, this is different at the nanoscale, where our hetero...

Novel approaches to materials design, fabrication processes and device architectures have accelerated next-generation electronics component production, pushing device dimensions down to the nano- and atomic-scale. For device metrology methods to keep up with these developments, they should not only measure the relevant electrical parameters at thes...

The operational stability of organic-inorganic halide perovskite based solar cells is a challenge for widespread commercial adoption. The mobility of ionic species is a key contributor to perovskite instability since ion migration can lead to unfavourable changes in the crystal lattice and ultimately destabilisation of the perovskite phase. Here we...

We have demonstrated the capabilities of the scanning microwave microscopy (SMM) technique for measuring ferromagnetic resonance (FMR) spectra in nanometric areas of magnetic samples. The technique is evaluated using three different samples, including an yttrium iron garnet (YIG) polycrystalline bulk sample and a thick YIG film grown by liquid phas...

Lithium-ion batteries are a key technology for electromobility; thus, quality control in cell production is a central aspect for the success of electric vehicles. The detection of defects and poor insulation behavior of the separator is essential for high-quality batteries. Optical quality control methods in cell production are unable to detect sma...

Development of future battery generations and quality control of current lithium-ion battery (LIB) systems require reliable techniques for the characterization of the complex dynamic processes in batteries. Electrochemical impedance spectroscopy (EIS) is an established tool for the electrochemical characterization of LIBs and the related ageing pro...

High frequency (GHz) signals are sent to a scanning tunneling microscope probe down to the surface of an alkylferrocene self‐assembled monolayer in liquid and allow to measure locally electrochemical charge transfer corresponding to currents on the order of attoampere. This technique, presented in article number 2101253 by Nicolas Clément, Georg Gr...

Electrochemical microscopy techniques have extended the understanding of surface chemistry to the micrometer and even sub‐micrometer level. However, fundamental questions related to charge transport at the solid‐electrolyte interface, such as catalytic reactions or operation of individual ion channels, require improved spatial resolutions down to t...

An electrochemical quartz crystal microbalance (EC-QCM) is a versatile gravimetric technique that allows for parallel characterization of mass deposition and electrochemical properties. Despite its broad applicability, simultaneous characterization of two electrodes remains challenging due to practical difficulties posed by the dampening from fixtu...

Electrochemical quartz crystal microbalance (EC-QCM) is a versatile gravimetric technique that allows for parallel characterization of mass deposition and electrochemical properties. Despite its broad applicability, simultaneous characterization of two electrodes remains challenging due to practical difficulties posed by the dampening from fixture...

Local electrochemical measurements and imaging at the nanoscale are crucial for the future development of molecular devices, sensors, materials engineering, electrophysiology and various energy applications from artificial photosynthesis to batteries. The ultimate step towards single-molecule sensitivity requires the measurement of aA currents, whi...

Nanoscale investigations by scanning probe microscopy have provided major contributions to the rapid development of organic-inorganic halide perovskites (OIHP) as optoelectronic devices. Further improvement of device level properties requires a deeper understanding of the performance-limiting mechanisms such as ion migration, phase segregation, and...

Integrated circuits and certain silicon-based quantum devices require the precise positioning of dopant nanostructures, and hydrogen resist lithography can be used to fabricate such structures at the atomic-scale limit. However, there is no single technique capable of measuring the three-dimensional location and electrical characteristics of these...

Nanoscale investigations by scanning probe microscopy have provided major contributions to the rapid development of organic-inorganic halide perovskites (OIHP) as optoelectronic devices. Further improvement of device level properties requires a deeper understanding of the performance-limiting mechanisms such as ion migration, phase segregation and...

Multitude of antennas are typically used in microwave imaging systems. Here we outline a simple and effective calibration method for multiport imaging systems. By using only one additional component, an electronic calibration module (ECal), one port is calibrated and the calibration plane is thereby moved to the antenna connector. Assuming all ante...

We investigate the nearfield dipole mobility of protein membranes in a wide frequency range from 3 kHz to 10 GHz. The results of our nanoscale dielectric images and spectra on bacteriorhodopsin (bR) reveal Debye relaxations with time constants of τ∼2ns and τ∼100ns being characteristic for the dipole moments of the bR retinal and the -helices, resp...

Two-dimensional transition metal dichalcogenide semiconductors have emerged as promising candidates for optoelectronic devices with unprecedented properties and ultra-compact footprints. However, the high sensitivity of atomically thin materials to the surrounding dielectric media imposes severe limitations on their practical applicability. Hence,...

A systematic and quantitative comparison of electrical detection systems in scanning microwave microscopy is reported. Scanning microwave microscopy (SMM) is capable of investigating nanoscale electrical properties with high accuracy over a broad frequency range of 1-20 GHz. However, due to the passive matching network only discrete frequencies can...

It is now possible to create atomically thin regions of dopant atoms in silicon patterned with lateral dimensions ranging from the atomic scale (angstroms) to micrometers. These structures are building blocks of quantum devices for physics research and they are likely also to serve as key components of devices for next-generation classical and quan...

We present a systematic and comprehensive study of the optical response of mechanically exfoliated WSe2 monolayer flakes encapsulated with dielectric SiOx and AlxOy oxide layers by employing different chemical and physical deposition techniques. Conformal flakes coating is successfully demonstrated by all the techniques except for atomic layer depo...

White Paper: Nanoscale impedance and permittivity properties at microwave frequencies using SMM - Volume 42 Issue 3 - Ferry Kienberger, Georg Gramse

A new calibration method for nanoscale complex impedance imaging with the scanning microwave microscope is presented, which allows to calibrate the complete frequency range in a short automated procedure. The vector network analyzer and the corresponding electronically switched calibration capabilities in combination with time domain gating and mic...

We quantitatively image the doping concentration and the capacitance of a high-voltage lateral metal-oxide-semiconductor transistor device with a channel length of 0.5 μm at 20-GHz frequency using scanning microwave microscopy (SMM). The transistor is embedded in a deep n-well forming a flat pn-junction with the p-substrate, with the shape of the p...

We obtained maps of electric permittivity at ∼19 GHz frequencies on non-planar thin film heterogeneous samples by means of combined atomic force-scanning microwave microscopy (AFM-SMM). We show that the electric permittivity maps can be obtained directly from the capacitance images acquired in contact mode, after removing the topographic cross-talk...

Broadband $dS_{11}/dV$ dopant profiling at GHz frequencies and in situ calibrated Capacitance-Voltage spectroscopy of silicon p-n junctions using Scanning Microwave Microscopy (SMM) are reported. Using a 3D finite element model to obtain the E-field distribution at the tip/sample interface, we show that the reflected $S_{11}$ signal is expected to...

Abstract In this work, microwave characterization of magnetic materials using the Scanning Microwave Microscopy (SMM) technique is presented. The capabilities of the SMM are employed for analyzing and imaging local magnetic properties of the materials under test at the nanoscale. The analyses are performed by acquiring both amplitude and phase of t...

The paper presents a methodology for de-embedding scanning microwave microscopy (SMM) measurements, mainly for semiconductor characterization. Analytical modeling, a parametric study and experimental verification are presented. The proposed methodology is based on the analysis of system response in the linear scale, instead of the dB scale commonly...

In this paper, we present in detail the design, both electromagnetic and mechanical, the fabrication, and the test of the first prototype of a Scanning Microwave Microscope (SMM) suitable for a two-port transmission measurement, recording, and processing the high frequency transmission scattering parameter S21 passing through the investigated sampl...

The application of scanning microwave microscopy (SMM) to extract calibrated electrical properties of cells and bacteria in air is presented. From the S 11 images, after calibration, complex impedance and admittance images of Chinese hamster ovary cells and E. coli bacteria deposited on a silicon substrate have been obtained. The broadband capabili...

We quantified the electric permittivity of single bacterial cells at microwave frequencies and nanoscale spatial resolution by means of near-field Scanning Microwave Microscopy (SMM). To this end, calibrated complex admittance images have been obtained at ~19 GHz and analyzed with a methodology that removes the non-local topographic cross-talk cont...

We measured and quantified the local electric polarization properties of ultrathin (∼5 nm) biolayers on mm-thick mica substrates. We achieved it by scanning a sharp conductive tip (<10 nm radius) of an electrostatic force microscope over the biolayers and quantifying sub-picoNewton electric polarization forces with a sharp-tip model implemented usi...

Reflection mode scanning microwave microscopy (SMM) is compared to a newly developed transmission mode imaging hardware for extended scattering S11 and S12 measurements. Transmission mode imaging is realized by an SMA connector placed below the sample to excite an electromagnetic wave towards the cantilever acting as nanoscale-sized receiver struct...

We present a new method to extract resistivity and doping concentration of semiconductor materials from Scanning Microwave Microscopy (SMM) S11 reflection measurements. Using a three error parameters de-embedding workflow, the S11 raw data are converted into calibrated capacitance and resistance images where no calibration sample is required. The S...

The 7500 SMM was used to measure Escherichia coli (E. coli) bacteria in air and in liquid using tapping mode for imaging soft materials. Quantitative SMM calibration is routinely achieved resulting in complex impedance images of bacteria in air including capacitance (aF; attoFarad) and conductance (μS; microSiemens) images. The calibrated capacitan...

In this work, we present the analytical modeling and preliminary experimental results for the choice of the optimal frequencies when performing amplitude and phase measurements with a scanning microwave microscope. In particular, the analysis is related to the reflection mode operation of the instrument, i.e., the acquisition of the complex reflect...

The capability of scanning microwave microscopy for calibrated sub-surface and non-contact capacitance imaging of silicon (Si) samples is quantitatively studied at broadband frequencies ranging from 1 to 20 GHz. Calibrated capacitance images of flat Si test samples with varying dopant density (1015–1019 atoms cm−3) and covered with dielectric thin...

We measured the DC and RF impedance characteristics of micrometric metal-oxide-semiconductor (MOS) capacitors and Schottky diodes using scanning microwave microscopy (SMM). The SMM consisting of an atomic force microscopy (AFM) interfaced with a vector network analyser (VNA) was used to measure the reflection S11 coefficient of the metallic MOS and...

The ability to observe and/or control physical phenomena at the nanoscale can be viewed as the backbone of most of the nanotechnology research conducted nowadays by scientist and engineers. Fast, accurate and versatile broadband microscopy techniques are required to image and characterize many complex and diverse nanoscale samples. One of such b...

This letter presents an algorithm for measuring the relative permittivity of thick dielectric substrates with scanning probe microscopy. Our technique does not rely on a specific type of microscopy setup and does not require expensive numerical field simulations. To demonstrate the versatility of our method, we perform measurements at high frequenc...

A numerical analysis of the polarization force between a sharp conducting probe and a dielectric film of finite lateral dimensions on a metallic substrate is presented with the double objective of (i) determining the conditions under which the film can be approximated by a laterally infinite film and (ii) proposing an analytical model valid in this...

We present a procedure for calibrated complex impedance measurements and dielectric quantification with scanning microwave microscopy. The calibration procedure works in situ directly on the substrate with the specimen of interest and does not require any specific calibration sample. In the workflow tip–sample approach curves are used to extract ca...

We use three-dimensional finite-element numerical simulations to fully characterize the electromagnetic interactions between a metallic nano-tip and cantilever that are part of a scanning microwave microscopy (SMM) system and dielectric samples. In particular, we use this rigorous computational technique to analyze and validate a recently developed...

The advent of the new nano-scale high speed materials and devices require metrology tools capable of characterization at the operating frequency range with nano-scale resolution. The non-destructive measurement of dopant profile and carrier concentration in 2D and 3D are critical in the new emerging materials and devices such as carbon nanotubes, g...

A theoretical analysis of amplitude modulated electrostatic force microscopy (AM-EFM) in liquid media at MHz frequencies, based on a simple tip-sample parallel plate model, is presented. The model qualitatively explains the main features of AM-EFM in liquid media and provides a simple explanation of how the measured electric forces are affected by:...

Many electrical scanning probe microscopy (SPM) techniques suffer from parasitic stray EM field contributions, which give rise to low signal to noise ratio and make the image retrieval process more difficult. Here, we validate via computational modeling a calibration procedure that employs three calibration standards and three complex coefficients...

We present what is, to our knowledge, the first experimental demonstration of dielectric constant measurement and quantification of supported lipid bilayers in electrolyte solutions with nanoscale spatial resolution. The dielectric constant was quantitatively reconstructed with finite element calculations by combining thickness information and loca...

We present the implementation of dynamic electrostatic force microscopy in liquid media. This implementation enables the quantitative imaging of local dielectric properties of materials in electrolyte solutions with nanoscale spatial resolution. Local imaging capabilities are obtained by probing the frequency-dependent and ionic concentration-depen...

We present a systematic analysis of the effects that the microscopic parts of electrostatic force microscopy probes (the cone and cantilever) have on the electrostatic interaction between the tip apex and thick insulating substrates (thickness > 100 μm). We discuss how these effects can influence the measurement and quantification of the local diel...

Quantitative measurement of the low-frequency dielectric constants of thick insulators at the nanoscale is demonstrated utilizing ac electrostatic force microscopy combined with finite-element calculations based on a truncated cone with hemispherical apex probe geometry. The method is validated on muscovite mica, borosilicate glass, polyethylene na...

A simple method to measure the static dielectric constant of thin films with nanometric spatial resolution is presented. The dielectric constant is extracted from DC electrostatic force measurements with the use of an accurate analytical model. The method is validated here on thin silicon dioxide films (8 nm thick, dielectric constant approximately...