Werner Frammelsberger
University of Applied Sciences Deggendorf
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Publication
Featured researches published by Werner Frammelsberger.
Applied Physics Letters | 2003
Dongping Liu; Günther Benstetter; Werner Frammelsberger
The nanowear resistance, tribological, and field emission properties of tetrahedral amorphous carbon (ta-C) films have been analyzed by atomic force microscope (AFM)-based wear testing technique, lateral force microscope, and conducting AFM. The ta-C films grown by filtered pulsed cathodic arc discharge were found to have soft surface layers, 1.1±0.1 nm thick, which contribute to an improvement of their field emission properties. The low friction coefficient between the nanotip and film surface is correlated to one or two graphite-like atomic layers at the ta-C film surfaces. The analysis of Fowler–Nordheim tunneling currents indicates the formation of filament-like emission channels in amorphous carbon films.
Microelectronics Reliability | 2007
Mario Lanza; M. Porti; M. Nafria; Guenther Benstetter; Werner Frammelsberger; Heiko Ranzinger; E. Lodermeier; G. Jaschke
Abstract In this work, the dependence of the electrical characteristics of some thin ( 2 , HfSiO and HfO 2 /SiO 2 stacks on their manufacturing process is studied at the nanoscale. Topography, current maps and current–voltage ( I – V ) characteristics have been collected by conductive atomic force microscope (CAFM), which show that their conductivity depends on some manufacturing parameters. Increasing the annealing temperature, physical thickness or Hafnium content makes the structure less conductive.
Microelectronics Reliability | 2006
W. Bergbauer; T. Lutz; Werner Frammelsberger; Guenther Benstetter
Light Emitting Diodes (LEDs) are commercially important devices in opto-semiconductor industry. The light emitting properties of LEDs degrade with time of operation and may lead to device failure. Even though the stability and reliability of LEDs are important topics, they are not well researched with AFM to date. This work demonstrates that Kelvin Probe Force Microscopy (KPFM) is an appropriate method to identify specific sites of increased degradation in a semiconductor heterostructure. Furthermore, the study shows that KPFM provides the metrological basis for further investigations with respect to the progress of degradation and its physical background. In this study, KPFM has been used to measure the potential gradient over cross-sectioned LED heterostructure in operation at different states of degradation. The results show significant differences between new and aged LEDs, markedly at specific layers of the LED heterostructure.
Review of Scientific Instruments | 2016
Yanfeng Ji; Fei Hui; Yuanyuan Shi; Vanessa Iglesias; David Lewis; Jiebin Niu; Shibing Long; Ming Liu; Alexander Hofer; Werner Frammelsberger; Guenther Benstetter; Andrew G. Scheuermann; Paul C. McIntyre; Mario Lanza
The conductive atomic force microscope (CAFM) has become an essential tool for the nanoscale electronic characterization of many materials and devices. When studying photoactive samples, the laser used by the CAFM to detect the deflection of the cantilever can generate photocurrents that perturb the current signals collected, leading to unreliable characterization. In metal-coated semiconductor samples, this problem is further aggravated, and large currents above the nanometer range can be observed even without the application of any bias. Here we present the first characterization of the photocurrents introduced by the laser of the CAFM, and we quantify the amount of light arriving to the surface of the sample. The mechanisms for current collection when placing the CAFM tip on metal-coated photoactive samples are also analyzed in-depth. Finally, we successfully avoided the laser-induced perturbations using a two pass technique: the first scan collects the topography (laser ON) and the second collects the current (laser OFF). We also demonstrate that CAFMs without a laser (using a tuning fork for detecting the deflection of the tip) do not have this problem.
Journal of Applied Physics | 2006
Dongping Liu; Günther Benstetter; Werner Frammelsberger
We have compared nanoscale electron field emissions from the bare, hydrogenated, and graphitelike-layer-covered tetrahedral amorphous carbon (ta-C) films. The electron field emission is investigated using a combination of atomic force microscopy (AFM)-based nanowear tests and conducting AFM, by simultaneously measuring the topography and the conductivity of the samples. The analysis of Fowler-Nordheim tunneling currents indicates the formation of filamentlike emission channels within ta-C films. The low-field emission from carbon films is primarily due to a field enhancement arising from conducting nanostructures inside the films. The implications of surface structures for electron field emission are discussed. Electrons are easily delocalized within sp2-bonded rings/chains at a film surface, which leads to an increase in the nanotip emission area. At identical emission currents of 60–80 pA, hydrogenated films are much more easily destroyed due to a relatively insulating surface structure. The results sug...
Scanning | 2017
Tobias Berthold; Guenther Benstetter; Werner Frammelsberger; R. Rodriguez; M. Nafria
For advanced atomic force microscopy (AFM) investigation of chemical surface modifications or very soft organic sample surfaces, the AFM probe tip needs to be operated in a liquid environment because any attractive or repulsive forces influenced by the measurement environment could obscure molecular forces. Due to fluid properties, the mechanical behavior of the AFM cantilever is influenced by the hydrodynamic drag force due to viscous friction with the liquid. This study provides a numerical model based on computational fluid dynamics (CFD) and investigates the hydrodynamic drag forces for different cantilever geometries and varying fluid conditions for Peakforce Tapping (PFT) in liquids. The developed model was verified by comparing the predicted values with published results of other researchers and the findings confirmed that drag force dependence on tip speed is essentially linear in nature. We observed that triangular cantilever geometry provides significant lower drag forces than rectangular geometry and that short cantilever offers reduced flow resistance. The influence of different liquids such as ultrapure water or an ethanol-water mixture as well as a temperature induced variation of the drag force could be demonstrated. The acting forces are lowest in ultrapure water, whereas with increasing ethanol concentrations the drag forces increase.
Applied Surface Science | 2007
Werner Frammelsberger; Guenther Benstetter; Janice Kiely; Richard Stamp
Thin Solid Films | 2015
Tobias Berthold; Guenther Benstetter; Werner Frammelsberger; R. Rodriguez; M. Nafria
Microelectronics Reliability | 2004
Guenther Benstetter; Peter Breitschopf; Werner Frammelsberger; Heiko Ranzinger; Peter Reislhuber; Thomas Schweinboeck
Applied Surface Science | 2015
Tobias Berthold; Guenther Benstetter; Werner Frammelsberger; R. Rodriguez; M. Nafria