Bojun Cheng


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Cheng

First Name

Bojun

ORCID

0000-0001-5551-4242

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2018 - 201992020 - 202419
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Publications1 - 10 of 28
  • Electrically Tunable Graphene Organic Hybrid Ring Resonators
    Item type: Conference Paper
    Ma, Ping; Zhang, X.Z.; Heni, Wolfgang; et al. (2021)
    2021 IEEE Photonics Conference (IPC)
  • Tip-enhanced atomic memristor – energy-efficient circuits and photon emission
    Item type: Doctoral Thesis
    Cheng, Bojun (2021)
    ETH Zürich Series in Electromagnetic Fields
  • Metasurface Colloidal Quantum Dot Photodetectors
    Item type: Journal Article
    Dordevic, Nikola; Schwanninger, Raphael; Yarema, Maksym; et al. (2022)
    ACS Photonics
    Efficient photodetectors that can be easily engineered for a specific spectral window are of high interest. Here, we report on the design, fabrication, and characterization of metasurface-enhanced photodetectors and photodiodes using colloidal quantum dots. We fabricate photoconductors optimized for the wavelength range around 1550 nm featuring responsivities of up to 8000 A/W with low noise equivalent powers on the order of tens of pW/Hz. Further, we produce photodiodes with responsivities of ∼5 mA/W that offer faster responses (14 μs rise time). The high responsivities are due to the metasurface, which increases the absorption by a factor of 10 compared to that of a quantum dot thin film of the same thickness and a structure that enables a photo-gain. We introduce a metasurface to detect either of the two orthogonal polarizations. The fabricated photoconductors operate at low voltages (1-5 V), making them compatible with the complementary metal-oxide-semiconductor (CMOS) read-out circuitry.
  • Overbias and Quantum Tunneling in Light-Emitting Memristors
    Item type: Journal Article
    Hamdad, Sarah; Malchow, Konstantin; Avetisyan, D.; et al. (2023)
    Physical Review Applied
    A nanoscale dielectric gap clamped between two metal electrodes may undergo a large resistance change from insulating to highly conducting upon applying an electrical stress. This sudden resistive switching is largely exploited in memristors for emulating synapses in neuromorphic neural networks. Here, we show that volatile resistive switching can be accompanied by a release of electromagnetic radiation spanning the visible spectral region. Of note, we find that the spectrum is characterized by photon energies exceeding the maximum kinetic energy of electrons provided by the switching voltage. This so-called overbias emission can be described self-consistently by a thermal radiation model featuring an out-of-equilibrium electron distribution generated in the device with an effective temperature exceeding 2000 K. The emitted spectrum is understood in terms of hot electrons radiatively decaying to resonant optical modes occurring in a nanoscale SiO₂ matrix located between two Ag electrodes. We further show that the same device can sustain different emission mechanisms depending on the nature, the intricacy and historicity of its memristive gap. Specifically, when operated in a nonvolatile state, we identify inelastic electron tunneling as an additional process providing photon emission from the device. The correlation between resistive switching and the onset of light emission in atomic scale photonic memristor brings alternative venues to generate light on chip and their exploitation in optical interconnects. Photons emitted during memristive switching can also be monitored to follow the neural activation pathways in memristor-based networks.
  • Threshold Switching Enabled Sub-pW-Leakage, Hysteresis-Free Circuits
    Item type: Journal Article
    Cheng, Bojun; Emboras, Alexandros; Passerini, Elias; et al. (2021)
    IEEE Transactions on Electron Devices
    In this article, we present ultralow leakage logic circuits by combining 3-D memristors with CMOS transistors. Significant leakage current reductions of up to 99% are found by experiments and simulation for a memristive hybrid-inverter if compared with a conventional inverter. Likewise, circuit simulations of memristive hybrid ring oscillators, NAND, or full adders show more than 100% gain in energy efficiency per cycle over state-of-the-art circuits. Importantly, the memristive circuits offer hysteresis-free operation. The hysteresis-free operation is due to properly engineered properties—such as the threshold voltage—of the memristors to match the circuit, as well as the self-adaptive filament diameter of our memristor during operation. Lastly, the memristors feature a 10 8 ON– OFF ratio, enabling both high speed and low leakage (~10 fA) when integrated with a transistor. They also come with a well-controlled filament formation on a ~10-nm footprint, making them ideal to integrate with modern CMOS technology transistors.
  • Broadband, Temperature-Stable, Reflective Additives to Enhance Thermal Radiation Protection Systems
    Item type: Conference Paper
    Christidis, George; Koch, Ueli; Poloni, Erik; et al. (2020)
    OSA Advanced Photonics Congress (AP) 2020 (IPR, NP, NOMA, Networks, PVLED, PSC, SPPCom, SOF)
    Metal-dielectric platelets are introduced as additives to heat protection systems. The platelets feature high reflectivity across 700 nm and thermal stability up to 1000°C. Impregnating aerospace heat shields improves thermal reflectivity by a factor 11.
  • Gate-Enabled Operation Point Tuning in an Atomic-Scale Memristor
    Item type: Other Conference Item
    Lewerenz, Mila; Passerini, Elias; Cheng, Bojun; et al. (2021)
  • Photon Emission by Silicon-Based Memristors
    Item type: Conference Paper
    Zellweger, Till; Cheng, Bojun; Malchow, Konstantin; et al. (2022)
    OSA Technical Digest ~ European Conference on Optical Communication (ECOC) 2022
    We introduce a new category of nanoscale photon sources based on memristors with silicon-based switching matrices. These novel photon sources exhibit light emission during the switching of their resistive state. The photon emission is attributed to the creation and excitation of silicon nanoclusters.
  • Single atom electronics and photonics
    Item type: Other Conference Item
    Leuthold, Juerg; Emboras, Alexandros; Cheng, Bojun; et al. (2018)
    Proceedings of SPIE ~ Silicon Photonics: From Fundamental Research to Manufacturing
    Scaling in the electronics industry according to Moor's law has recently been slowing down. Further size reductions will ultimately lead to an atomic scale electronics. However, how viable is such an atomic scale technology? Photonics too has undergone quite some size reduction. The ultimate limit is set by the wavelength and the refractive index. The question then is if there is room for scaling beyond the Abbe diffraction limit? In this talk we will review recent advances in the field of an atomic scale electronics and photonics.
  • Atomic-Scale Memristive Plasmonics
    Item type: Conference Paper
    Leuthold, Juerg; Cheng, Bojun; Koch, Ueli; et al. (2022)
    OSA Technical Digest ~ Optica Advanced Photonics Congress 2022
    Plasmonics is a powerful tool to miniaturize photonics. In this review, we introduce memristive plasmonics as a technique to shrink photonic devices to the atomic scale. We show atomic-scale plasmonic switches, detectors and emitters.
Publications1 - 10 of 28