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1. Silicon‐On‐Silicon Carbide Platform for Integrated Photonics

   https://doi.org/10.1002/adom.202401101  

   DeVault, Clayton_T; Deckoff‐Jones, Skylar; Liu, Yuzi; Hammock, Ian_N; Sullivan, Sean_E; Dibos, Alan; Sorce, Peter; Orcutt, Jason; Awschalom, David_D; Heremans, F_Joseph; et al (August 2024, Advanced Optical Materials)

   Abstract Silicon carbide (SiC)'s nonlinear optical properties and applications to quantum information have recently brought attention to its potential as an integrated photonics platform. However, despite its many excellent material properties, such as large thermal conductivity, wide transparency window, and strong optical nonlinearities, it is generally a difficult material for microfabrication. Here, it is shown that directly bonded silicon‐on‐silicon carbide can be a high‐performing hybrid photonics platform that does not require the need to form SiC membranes or directly pattern in SiC. The optimized bonding method yields defect‐free, uniform films with minimal oxide at the silicon–silicon–carbide interface. Ring resonators are patterned into the silicon layer with standard, complimentary metal–oxide–semiconductor (CMOS) compatible (Si) fabrication and measure room‐temperature, near‐infrared quality factors exceeding 10⁵. The corresponding propagation loss is 5.7 dB cm⁻¹. The process offers a wafer‐scalable pathway to the integration of SiC photonics into CMOS devices. 

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2. (Invited) Silicon Nanosheets as Candidates for Silicon-Based Optoelectronics

   https://doi.org/10.1149/10201.0003ecst  

   Ryan, Bradley J.; Diroll, Benjamin T.; Guo, Yuqi; Dolgos, Carly J.; Wang, Qing Hua; Roling, Luke T.; Panthani, Matthew G (May 2021, ECS Transactions)

   The growth in computational ability over the past decades has positively impacted global development, the economy, healthcare, and science. As on-chip components are approaching the atomic scale, alternative paradigms are needed to address the thermal and electronic issues that impose bottlenecks for computing. One approach to address this is with optoelectronics. However, silicon—the backbone of microelectronics—is a poor choice due to its indirect bandgap, while existing optoelectronic materials are incompatible with CMOS infrastructure. Monolayer silicon nanosheets (SiNSs) are an intriguing material that exhibit photoluminescence, and are compositionally-compatible with the CMOS process. Here, we synthesize and characterize monolayer SiNSs, and show spectroscopic evidence that they exhibit a quasi-direct bandgap, which is corroborated by DFT calculations. We probe their thermal stability, demonstrating their structure and photoluminescence are stable beyond the required operating temperatures for computing applications. These optoelectronic properties, CMOS-compatibility, and stability make SiNSs a viable candidate for silicon-based photonics. 

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3. Spin-acoustic control of silicon vacancies in 4H silicon carbide

   https://doi.org/10.1038/s41928-023-01029-4  

   Dietz, Jonathan_R; Jiang, Boyang; Day, Aaron_M; Bhave, Sunil_A; Hu, Evelyn_L (September 2023, Nature Electronics)

   Abstract Bulk acoustic resonators can be fabricated on the same substrate as other components and can operate at various frequencies with high quality factors. Mechanical dynamic metrology of these devices is challenging as the surface information available through laser Doppler vibrometry lacks information about the acoustic energy stored in the bulk of the resonator. Here we report the spin-acoustic control of naturally occurring negatively charged silicon monovacancies in a lateral overtone bulk acoustic resonator that is based on 4H silicon carbide. We show that acoustic driving can be used at room temperature to induce coherent population oscillations. Spin-acoustic resonance is shown to be useful as a frequency-tunable probe of bulk acoustic wave resonances, highlighting the dynamical strain distribution inside a bulk acoustic wave resonator at ambient operating conditions. Our approach could be applied to the characterization of other high-quality-factor microelectromechanical systems and has the potential to be used in mechanically addressable quantum memory. 

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4. Post-Silicon Microarchitecture

   https://doi.org/10.1109/LCA.2020.2978841  

   Kumar, Chanchal; Chaudhary, Aayush; Bhawalkar, Shubham; Mathur, Utkarsh; Jain, Saransh; Vastrad, Adith; Rotenberg, Eric (January 2020, IEEE Computer Architecture Letters)
5. Spin polarization through intersystem crossing in the silicon vacancy of silicon carbide

   https://doi.org/doi.org/10.1103/PhysRevB.99.184102  

   Dong, Wenzheng; Doherty, M. W.; Economou, Sophia E. (May 2019, Physical review. B, Condensed matter)

   Silicon carbide (SiC)-based defects are promising for quantum communications, quantum information processing, and for the next generation of quantum sensors, as they feature long coherence times, frequencies near the telecom, and optical and microwave transitions. For such applications, the efficient initialization of the spin state is necessary. We develop a theoretical description of the spin-polarization process by using the intersystem crossing of the silicon vacancy defect, which is enabled by a combination of optical driving, spin-orbit coupling, and interaction with vibrational modes. By using distinct optical drives, we analyze two spin-polarization channels. Interestingly, we find that different spin projections of the ground state manifold can be polarized. This paper helps in understanding initialization and readout of the silicon vacancy and explains some existing experiments with the silicon vacancy center in SiC. 

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