Tall, crystalline carbon nanotubes (CNTs) are desired to successfully integrate them in various applications. As the crystallinity of CNTs improves with increasing growth temperatures, higher growth temperatures are required to obtain crystalline CNTs. However, in a typical chemical vapor deposition (CVD) process, CNT growth rate reduces when the growth temperature exceeds a specific level due to the degradation of the catalyst particles. In this study, we have demonstrated the improved catalytic activity of nickel/ferrocene-hybridized catalyst as compared to sole ferrocene catalyst. To demonstrate this, CNTs are grown on bare silicon (Si) as well as nickel (Ni) catalyst-deposited substrates using volatile catalyst source (ferrocene/xylene) CVD at the growth temperatures ranging from 790 to 880 °C. It was found that CNTs grown on bare Si substrate experience a reduction in height at growth temperature above 860 °C, whereas the CNTs grown on 10 nm Ni catalyst-deposited substrates experience continuous increase in height as the temperature increases from 790 to 880 °C. The enhancement in the height of CNTs by the addition of Ni catalyst is also demonstrated on 5, 20, and 30 nm Ni layers. The examination of CNTs using electron microscopy and Raman spectra shows that the additional Ni catalyst source improves the CNT growth rates and crystallinity, yielding taller CNTs with a high degree of structural crystallinity.

In this work, silicon photonics structures for the optical addressing of trapped ion is developed for quantum computing applications. Grating-waveguide-grating structures of various designs are designed, and fabricated for various radius curvatures of 12, 15, 25 and 30 µm, respectively. From the optical measurements, gratings with radius of curvature of 25 and 30 µm exhibit lower power loss of 36.5 and 33.9 dB with better-focused beam profiles as compared to those with radius of curvature of 12 and 15 µm. The beam width from these gratings ranges between 17.31 to 41.54 µm, which provides the feasibility to perform optical addressing on 2 to 4 Sr + ions trapped along the ground electrode of the ion trap.

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As a novel class of two-dimensional materials, MXene has provoked tremendous progress for various applications in functional devices. Here, we pioneer a preliminary understanding on the field emission behavior of MXene for the first time. Ti3C2 paper is fabricated by using facile filtration method, and multiple vertical sheets appear on the surface of MXene paper with high electrical conductivity (2.93 × 105 S m−1) and low work function (3.77 eV). The field electron emission performance and electric field distribution on MXene emitters are measured and simulated under planar and standing conditions. Both emitter conditions exhibit stable, uniform electron emission pattern, and the standing emitter achieves high emission current density of 59 mA cm−2 under 7.5 V μm−1. This work demonstrates the feasibility of MXene as cold electron source, establishing a preliminary foundation for its applications in field emission-based devices.

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This study presents the design and development of surface electrode ion traps on glass and Si substrate, as well as their RF characterizations and performance benchmarking. In this case, ion-trap on-glass shows superior performances in all necessary criteria. In terms of RF characterizations, ion-traps on glass have Q factor of greater than 900. This is significantly higher than the Q factor of its silicon counterparts, which are around 20 -300. Such a high Q factor results in power spectral density (PSD) of greater than 10W/MHz. On the other hand, iontraps on-silicon produce PSD values of lower than 3W/MHz. In terms of RF performance, ion-trap on-glass shows insertion loss lower than 0.2 dB at 60MHz. This is more superior to insertion loss values of ion-traps on-silicon, which are around 1 -4 dB. The ion-traps metallization is developed using three metallization layers (0.1µm Ti barrier layer, 2.5 -3.7µm Cu, and 0.3µm Au) on top of dielectric. The on-chip resonance condition can be maintained upon the packaging integration. The laser optical setup for ion-trapping is verified to capture single 88 Sr + ion.

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