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- ItemModulation Linearity Characterization of Si Ring Modulators(Washington, DC : OSA, 2021) Jo, Youngkwan; Mai, Christian; Lischke, Stefan; Zimmermann, Lars; Choi, Woo-YoungModulation linearity of Si ring modulators (RMs) is investigated through the numerical simulation based on the coupled-mode theory and experimental verification. Numerical values of the key parameters needed for the simulation are experimentally extracted. Simulation and measurement results agree well. With these, the influence of input optical wavelength and power on the Si RM linearity are characterized.
- ItemSi photonic-electronic monolithically integrated optical receiver with a built-in temperature-controlled wavelength filter(Washington, DC : Soc., 2021) Kim, Hyun-Kyu; Kim, Minkyu; Kim, Min-Hyeong; Jo, Youngkwan; Lischke, Stefan; Mai, Christian; Zimmermann, Lars; Choi, Woo-YoungWe present a Si photonic-electronic integrated ring-resonator based optical receiver that contains a temperature-controlled ring-resonator filter (RRF), a Ge photodetector, and receiver circuits in a single chip. The temperature controller automatically determines the RRF temperature at which the maximum transmission of the desired WDM signal is achieved and maintains this condition against any temperature or input wavelength fluctuation. This Si photonic-electronic integrated circuit is realized with 0.25-µm photonic BiCMOS technology, and its operation is successfully confirmed with measurement.
- ItemOn the electronic properties of a single dislocation(College Park : American Institute of Physics Inc., 2014) Reiche, M.; Kittler, M.; Erfurth, W.; Pippel, E.; Sklarek, K.; Blumtritt, H.; Haehnel, A.; Uebensee, H.A detailed knowledge of the electronic properties of individual dislocations is necessary for next generation nanodevices. Dislocations are fundamental crystal defects controlling the growth of different nanostructures (nanowires) or appear during device processing. We present a method to record electric properties of single dislocations in thin silicon layers. Results of measurements on single screw dislocations are shown for the first time. Assuming a cross-section area of the dislocation core of about 1 nm2, the current density through a single dislocation is J = 3.8 × 1012 A/cm2 corresponding to a resistivity of ρ ≅ 1 × 10-8 Ω cm. This is about eight orders of magnitude lower than the surrounding silicon matrix. The reason of the supermetallic behavior is the high strain in the cores of the dissociated dislocations modifying the local band structure resulting in high conductive carrier channels along defect cores.
- ItemEngineering the semiconductor/oxide interaction for stacking twin suppression in single crystalline epitaxial silicon(111)/insulator/Si(111) heterostructures(College Park, MD : Institute of Physics Publishing, 2008) Schroetter, T.; Zaumseil, P.; Seifarth, O.; Giussani, A.; Müssig, H.-J.; Storck, P.; Geiger, D.; Lichte, H.; Dabrowski, J.The integration of alternative semiconductor layers on the Si material platform via oxide heterostructures is of interest to increase the performance and/or functionality of future Si-based integrated circuits. The single crystalline quality of epitaxial (epi) semiconductor-insulator-Si heterostructures is however limited by too high defect densities, mainly due to a lack of knowledge about the fundamental physics of the heteroepitaxy mechanisms at work. To shed light on the physics of stacking twin formation as one of the major defect mechanisms in (111)-oriented fcc-related heterostructures on Si(111), we report a detailed experimental and theoretical study on the structure and defect properties of epi-Si(111)/Y2O 3/Pr2O3/Si(111) heterostructures. Synchrotron radiation-grazing incidence x-ray diffraction (SR-GIXRD) proves that the engineered Y2O3/Pr2O3 buffer dielectric heterostructure on Si(111) allows control of the stacking sequence of the overgrowing single crystalline epi-Si(111) layers. The epitaxy relationship of the epi-Si(111)/insulator/Si(111) heterostructure is characterized by a type A/B/A stacking configuration. Theoretical ab initio calculations show that this stacking sequence control of the heterostructure is mainly achieved by electrostatic interaction effects across the ionic oxide/covalent Si interface (IF). Transmission electron microscopy (TEM) studies detect only a small population of misaligned type B epi-Si(111) stacking twins whose location is limited to the oxide/epiSi IF region. Engineering the oxide/semiconductor IF physics by using tailored oxide systems opens thus a promising approach to grow heterostructures with well-controlled properties. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
- ItemQuantitative protein sensing with germanium THz-antennas manufactured using CMOS processes(Washington, DC : Soc., 2022) Hardt, Elena; Chavarin, Carlos Alvarado; Gruessing, Soenke; Flesch, Julia; Skibitzki, Oliver; Spirito, Davide; Vita, Gian Marco; Simone, Giovanna De; Masi, Alessandra di; You, Changjiang; Witzigmann, Bernd; Piehler, Jacob; Capellini, GiovanniThe development of a CMOS manufactured THz sensing platform could enable the integration of state-of-the-art sensing principles with the mixed signal electronics ecosystem in small footprint, low-cost devices. To this aim, in this work we demonstrate a label-free protein sensing platform using highly doped germanium plasmonic antennas realized on Si and SOI substrates and operating in the THz range of the electromagnetic spectrum. The antenna response to different concentrations of BSA shows in both cases a linear response with saturation above 20 mg/mL. Ge antennas on SOI substrates feature a two-fold sensitivity as compared to conventional Si substrates, reaching a value of 6 GHz/(mg/mL), which is four-fold what reported using metal-based metamaterials. We believe that this result could pave the way to a low-cost lab-on-a-chip biosensing platform.
- ItemA graphene-based hot electron transistor(Washington, DC : American Chemical Society, 2013) Vaziri, S.; Lupina, G.; Henkel, C.; Smith, A.D.; Östling, M.; Dabrowski, J.; Lippert, G.; Mehr, W.; Lemme, M.C.We experimentally demonstrate DC functionality of graphene-based hot electron transistors, which we call graphene base transistors (GBT). The fabrication scheme is potentially compatible with silicon technology and can be carried out at the wafer scale with standard silicon technology. The state of the GBTs can be switched by a potential applied to the transistor base, which is made of graphene. Transfer characteristics of the GBTs show ON/OFF current ratios exceeding 104.