Publikationen 2025

Script list Publications

(1) When to Use Rectangular Waveforms in Dielectrophoresis Application to Increase Separation and Sorting Efficiency
N. Boldt, L. Weirauch, J.M. Späth, U. Kerst, M. Birkholz, M. Baune, R. Thewes
Electrophoresis 46(1-2), 104 (2025)
DOI: 10.1002/elps.202400164, (Bioelectronics)
In this study, the influence of using rectangular waveforms is comprehensively investigated on the separation and sorting efficiency of dielectrophoretic (DEP) processes. Besides positive effects on DEP experiments cases for a diminished force due to rectangular waveforms are investigated and discussed. This investigation encompasses two primary experimental setups. Firstly, microparticle focusing experiments are carried out using a pair of electrodes within a microfluidic channel. Secondly, separation experiments are performed using a macroscopic insulator-based dielectrophoretic filter. The study reveals that harmonics of rectangular signals can have a positive impact on separation or sorting efficiency when compared to sinusoidal waveforms, provided that these harmonics contribute to the overall DEP force with the same sign. This positive effect is found to depend on the ratio between applied fundamental frequency and the cross-over frequency in the Clausius-Mossotti factor. However, violating related derived boundary conditions leads to negative effects and a decrease of the DEP net force.

(2) Investigating Impacts of Local Pressure and Temperature on CVD Growth of Hexagonal Boron Nitride on Ge(001)/Si
M. Franck, J. Dabrowski, M.A. Schubert. D. Vignaud, M. Achehboune, J.-F. Colomer, L. Henrard, Ch. Wenger, M. Lukosius
Advanced Materials Interfaces 12(1), 2400467 (2025)
DOI: 10.1002/admi.202400467, (2DHetero)
The chemical vapor deposition (CVD) growth of hexagonal boron nitride (hBN) on Ge substrates is a promising pathway to high-quality hBN thin films without metal contaminations for microelectronic applications, but the effect of CVD process parameters on the hBN properties is not well understood yet. The influence of local changes in pressure and temperature due to different reactor configurations on the structure and quality of hBN films grown on Ge(001)/Si is studied. Injection of the borazine precursor close to the sample surface results in an inhomogeneous film thickness, attributed to an inhomogeneous pressure distribution at the surface, as shown by computational fluid dynamics simulations. The additional formation of nanocrystalline islands is attributed to unfavorable gas phase reactions due to the radiative heating of the injector. Both issues are mitigated by increasing the injector-sample distance, leading to an 86% reduction in pressure variability on the sample surface and a 200 °C reduction in precursor temperature. The resulting hBN films exhibit no nanocrystalline islands, improved thickness homogeneity, and high crystalline quality (Raman FWHM = 23 cm−1). This is competitive with hBN films grown on other non-metal substrates but achieved at lower temperature and with a low thickness of only a few nanometers.

(3) A High-Gain 240-325-GHz Power Amplifier for IEEE 802.15.3d Applications in an Advanced BiCMOS Technology
A. Gadallah, A. Malignaggi, B. Sütbas, H. Rücker, D. Kissinger, M.H. Eissa
Proc. 25th IEEE Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SiRF 2025), 19 (2025)
(Open 6G Hub)

(4) Strategies to Realize AC Electrokinetic Enhanced Mass-Transfer in Silicon based Photonic Biosensors
A. Henriksson, P. Neubauer, M. Birkholz
Advanced Materials Technologies 10(2), 2302191 (2024)
DOI: 10.1002/admt.202302191, (Bioelectronics)
Silicon-on-insulator (SOI) based photonic sensors, particularly those utilizing Photonic Integrated Circuit (PIC) technology, have emerged as promising candidates for miniaturized bioanalytical devices. These sensors offer real-time responses, occupy minimal space, possess high sensitivity, and facilitate label-free detection. However, like many biosensors, they face challenges when detecting analytes at exceedingly low concentrations due to limitations in mass transport. An intriguing method to enhance mass transfer in microfluidic biosensors is AC electrokinetics. Proof-of-concept experiments have demonstrated significant enhancements in limit of detection (LOD) and response times. AC electrokinetics, compatible with silicon photonic sensors, offers techniques such as electroosmosis, electrothermal effects, and dielectrophoresis to modify fluid flow and manipulate particle trajections. This article delves into various approaches for integrating AC electrokinetics into silicon photonic biosensors, shedding light on both its advantages and limitations.

(5) 44 GHz Bandwidth Optical Receiver Monolithically Integrated in a SiGe ePIC BiCMOS Technology
F. Iseini, N. Pelagalli, A. Malignaggi, A. Peczek, C. Carta, G. Kahmen
20th IEEE Radio & Wireless Week (RWW 2025), 12 (2025)
(100G)

(6) High-Sensitive Broadband Terahertz Detectors for Hyperspectral Imaging
V. Jagtap, U. Kalita, R. Jain, H. Rücker, B. Heinemann, U.R. Pfeiffer
Imaging Sensors, Power Management, PLLs and Frequency Synthesizers, 1st Edition, Editors: K.A.A. Makinwa, A. Baschirotto, B. Nauta, Chapter. High-Sensitive Broadband Terahertz Detectors for Hyperspectral Imaging, Springer, 99 (2025)
DOI: 10.1007/978-3-031-71559-4

(7) Growth of Boron-Doped Germanium Single Crystals by the Czochralski Method
A.N. Subramanian, M.P. Kabukcuoglu, C. Richter, U. Juda, R. Kernke, F. Bärwolf, E. Hamann, M. Zuber, N.V. Abrosimov, R.R. Sumathi
Crystal Growth & Design 25(4), 1075 (2025)
DOI: 10.1021/acs.cgd.4c01413
In this paper, we present the growth of boron-doped germanium single crystals using the Czochralski method. Boron was introduced into the solid phase prior to the initiation of the growth experiment. Enhanced dissolution of boron in the germanium melt was observed at higher temperatures, facilitating the single crystalline growth. The distribution of boron along the crystal length was quantified at several positions using secondary ion mass spectrometry, with concentrations reaching up to 1018 atoms/cm3 near the seed (top region) of the grown crystals. These results are compared with the theoretically predicted boron segregation profile calculated using the Scheil–Pfann equation. Additionally, the structural quality of the crystals was examined by using etch pit density measurement and X-ray diffraction techniques, including synchrotron white-beam X-ray topography and X-ray rocking curve imaging. It is shown that variations in boron concentrations in the 0–0.5 solidified fractions (g) of the grown crystals lead to a strain field along the growth direction. Finally, the feasibility and challenges of growing heavily boron-doped germanium crystals from the melt while maintaining a single crystallinity with a low dislocation density are discussed.

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