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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Electromagnetic Characterization and Design Note of a Sub-THz SiGe Voltage-controlled Oscillator
摘要： In this paper we present the electromagnetic (EM) characterization and some design notes of a sub-Terahertz voltage-controlled oscillator (VCO) based on a push-push architecture and realized based on Colpitts-type oscillators. The circuit operates at both 0.192 GHz and 0.384 THz the frequencies and is implemented in a 130 nm SiGe bipolar technology provided by IHP foundry.
关键词： SiGe bipolar technology,push-push architecture,voltage-controlled oscillator,sub-THz,Colpitts-type oscillators
更新于2025-09-19 17:13:59
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Nanoscale characterization of photonic metasurface made of lens-like SiGe Mie-resonators formed on Si (100) substrate
摘要： Submicrometer-sized high-index Mie resonators attract significant interest in photonic applications due to their capabilities to manipulate light. 2-dimensional metamaterials or metasurfaces consisting of arrays of such resonators on a device surface can be used in the flat optics, sensors, and other applications. Here, we report on the comprehensive nanoscale characterization and optical properties of nearly regular SiGe Mie resonator arrays on a Si surface fabricated using a simple and low-cost method. We achieved control on the surface morphology by depositing Ge on the Si(100) surface at elevated temperatures 890–960 °C and obtained arrays of submicrometer/micrometer low-Ge-content SiGe lenslike islands via dewetting when the Ge content was >4%. At the lower Ge content, we observed the formation of a continuous SiGe film via wetting. We used Raman microscopy not only for the Ge content and stress control but also for studying photonic properties of the islands and their coupling with the Si substrate. In contrast to the elastic light scattering, we clearly distinguished visible light Raman signals from the islands themselves and from the substrate areas under the islands enhanced compared to the signal from the open substrate. Calculation of the light electric field distribution in the islands and the substrate demonstrate how the islands trap the light and forward it into the high-index substrate. This explains the island-induced reflection suppression and Si substrate Raman enhancement, which we observe experimentally. Such an SiGe-island array is a promising metasurface for the improvement of Si photosensors and solar-energy device performance.
关键词： SiGe,metasurfaces,photonic properties,Mie resonators,Raman microscopy
更新于2025-09-16 10:30:52
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[IEEE ESSDERC 2019 - 49th European Solid-State Device Research Conference (ESSDERC) - Cracow, Poland (2019.9.23-2019.9.26)] ESSDERC 2019 - 49th European Solid-State Device Research Conference (ESSDERC) - Design and Characterization of Monolithic Microring Resonator based Photodetector in 45nm SOI CMOS
摘要： This paper presents a characterization and a compact model of microring resonator based photodetector designed in a monolithic silicon-photonic platform. As these detectors are inherently wavelength selective they can potentially enable fully integrated DWDM optical receivers. The detector makes use of resonance enhancement in a microring by integrating 30 interleaved lateral P-N junctions along a 5μm radius microring cavity. The performance measurements reveal a peak responsivity of 0.6 A/W at 1270nm with <1nA dark current and <20fF junction capacitance at -7.5V reverse bias.
关键词： DWDM,silicon-photonics,monolithic,microring resonator,SiGe,integrated heater,CMOS,photodetector,SOI
更新于2025-09-12 10:27:22
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[IEEE 2019 14th European Microwave Integrated Circuits Conference (EuMIC) - Paris, France (2019.9.30-2019.10.1)] 2019 14th European Microwave Integrated Circuits Conference (EuMIC) - A Broadband Antenna-Coupled Terahertz Direct Detector in a 0.13-μm SiGe HBT Technology
摘要： This paper presents an integrated silicon-lens coupled THz direct detector. It comprises a pair of differentially driven antenna-coupled HBT transistors in common-base configuration implemented in an advanced 0.13-μm SiGe HBT technology with fT/fmax of 350/550 GHz. Based on the antenna detector co-design approach, a broadband operation with an optical noise equivalent power (NEP) lower than 40 pW/√Hz in the measured 220 GHz to 1 THz band is achieved. The detector operates in a voltage mode readout with an external resistance of 1.83 k?. Two device regions have been investigated. In the forward-active mode the detector achieves its minimum NEP of 1.9 pW/√Hz from 275 to 525 GHz at 100 kHz chopping frequency. The maximum voltage responsivities (Rv) are 9 kV/W and around 7.5 kV/W respectively. In the saturation region the minimum measured NEP from 220 GHz to 1 THz is 5.1 pW/√Hz at 292 GHz and values less than 4.3 pW/√Hz.
关键词： HBT,NEP,SiGe,on-chip antenna,Terahertz detector
更新于2025-09-12 10:27:22
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Low-frequency charge noise in Si/SiGe quantum dots
摘要： Electron spins in silicon have long coherence times and are a promising qubit platform. However, electric field noise in semiconductors poses a challenge for most single- and multiqubit operations in quantum-dot spin qubits. We investigate the dependence of low-frequency charge noise spectra on temperature and aluminum-oxide gate dielectric thickness in Si/SiGe quantum dots with overlapping gates. We find that charge noise increases with aluminum-oxide thickness. We also find strong dot-to-dot variations in the temperature dependence of the noise magnitude and spectrum. These findings suggest that each quantum dot experiences noise caused by a distinct ensemble of two-level systems, each of which has a nonuniform distribution of thermal activation energies. Taken together, our results suggest that charge noise in Si/SiGe quantum dots originates at least in part from a nonuniform distribution of two-level systems near the surface of the semiconductor.
关键词： temperature dependence,two-level systems,gate dielectric thickness,Si/SiGe quantum dots,charge noise
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - N-Type Ge/SiGe Quantum Cascade Heterostructures for THz Emission
摘要： Terahertz (THz) semiconductor based quantum cascade lasers (QCLs) represent powerful and compact integrated light sources. To date they have been realized with various III-V materials where LO phonon emission becomes very effective as the temperature is increased, limiting the maximum operating temperature to 200K. To overcome this limitation, non-polar material systems are attractive because of their weaker e-phonon interaction. Theoretical studies have indicated n-type Ge/SiGe heterostructures where transport is associated to L electrons, as the most promising architecture [1]. Experimentally, sharp intersubband transitions in n-type strain compensated Ge/SiGe QWs have been observed in the 20-50 meV region [2]. Recently, non-equilibrium Green’s functions calculations proved to be efficient in optimising high temperature performance of GaAs/AlGaAs THZ QCLs [3]. In the effort of realizing a Ge/SiGe THz QCL, we present here a QCL structure designed by means of non-equilibrium Green’s functions [4], whose the bandstructure is reported in Fig.1(a). Epitaxial growth of strain-compensated Ge/SiGe heterostructure (≈1.5 μm thick) has been carried out by means of UHV-CVD yielding very good sample quality as visible from Fig.1(b). Mesa devices for transport experiments have been fabricated by dry etching and metallization. In Fig.1(c) a series of I-V curves as a function of the heatsink temperature display a thermally activated behaviour with Eact (cid:3) 10 meV. From low temperature (4 K) magnetotransport [5] in a magnetic field parallel to the current direction shows characteristics oscillations. we can deduce an energy distance between the lasing states of E23 =19.5 meV, in good agreement with the theoretical calculation. Optical experiments are ongoing and experimental results will be presented.
关键词： THz,UHV-CVD,quantum cascade lasers,Ge/SiGe heterostructures,non-equilibrium Green’s functions
更新于2025-09-11 14:15:04
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A SiGe BiCMOS phase shifter based on quarter‐wave coupled resonators
摘要： This work presents the first example of monolithically integrated phase shifter based on a pass-band filter architecture. The proposed configuration was realized mapping a classical quarter-wave coupled filter circuit into its lumped element equivalent. Phase control is achieved by controlling the pass-band through tunable tanks employing varactor diodes. A demonstrator was prototyped in the 24 GHz ISM band using a 0.25μm SiGe BiCMOS technology. Experimental results show 180° of phase range and maximum transmission losses of 8 dB. The main feature of this configuration is that it allows controlling the transmission losses by design and that its size is extremely compact.
关键词： SiGe BiCMOS,varactor,phase shifter,pass-band
更新于2025-09-11 14:15:04
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n-type Ge/SiGe Multi Quantum-Wells for a THz Quantum Cascade Laser
摘要： Exploiting intersubband transitions in Ge/SiGe quantum cascade devices provides a way to integrate terahertz light emitters into silicon-based technology. With the view to realizing a Ge/SiGe Quantum Cascade Laser, we present the optical and structural properties of n-type strain-symmetrized Ge/SiGe asymmetric coupled quantum wells grown on Si(001) substrates by means of ultrahigh vacuum chemical vapor deposition. We demonstrate high material quality of strain-symmetrized structures and heterointerfaces as well as control over inter-well coupling and electron tunneling. Motivated by the promising results obtained on ACQWs, which are the basic building block of a cascade structure, we investigate, both experimentally and theoretically, a Ge/SiGe THz QCL design, optimized through a non-equilibrium Green’s function formalism.
关键词： Ge/SiGe,THz,intersubband transitions,strain-symmetrized,Quantum Cascade Laser
更新于2025-09-11 14:15:04
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Cryogenic Characterization of RF Low-Noise Amplifiers Utilizing Inverse-Mode SiGe HBTs for Extreme Environment Applications
摘要： The cryogenic performance of radiation-hardened radio-frequency (RF) low-noise amplifiers (LNAs) is presented. The LNA, which was originally proposed for the mitigation of single-event transients (SETs) in a radiation environment, uses inverse-mode silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) in its core cascode stages. In this prototype, the upper common-base SiGe HBT is configured in inverse mode for balanced RF performance and reduced SET sensitivity. In order to better exploit the inverse-mode LNAs in a variety of extreme-environment applications, the RF performance of the LNA was characterized using liquid nitrogen to evaluate cryogenic operation down to 78 K. While the SiGe LNA exhibits acceptable RF performance for all temperature conditions, there is a noticeable gain drop observed at 78 K compared to the conventional forward-mode design. This is attributed to the limited high-frequency performance of an inverse-mode SiGe HBT. As a guideline, compensation techniques including layout modifications and profile optimization are discussed for the mitigation of the observed gain degradation.
关键词： low-noise amplifier (LNA),heterojunction bipolar transistor (HBT),cascode,inverse mode,extreme environment,cryogenic measurement,silicon-germanium (SiGe)
更新于2025-09-11 14:15:04
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - A Full-Array-Grid-Compatible Wideband Tx/Rx Multipack using Multifunctional Chips on GaN and SiGe
摘要： A next generation of RF sensor modules for multi-function AESA systems shall provide a combination of different operating modes, e.g. Radar, EW and Communications/Datalink within the same antenna frontend. Typical operating frequencies covering C-Band, X-Band and Ku-Band will require a bandwidth of > 10 GHz, here. As for the realisation of modern active electronically steered antennas (AESA) the Transmit/Receive (Tx/Rx) Modules have to match with geometry constraints a major challenge for these future multifunction RF sensor modules is given by the half-wavelength grid demand derived from the highest frequency with accordant need for grating lobe free Field of View. One key to overcome this geometry demand can be the reduction of the total MMIC chip area with a “high-level” integration of single chip based RF functions into new multifunctional MMICs realised in SiGe- and GaN-technology. Further channel width reduction can be achieved by realising Tx/Rx multipacks instead of single-channel Tx/Rx Modules.
关键词： Multifunctional,Wideband,GaN,Tx/Rx Module,SiGe
更新于2025-09-11 14:15:04