15 research outputs found
Superconducting Diamond on Silicon Nitride for Device Applications
Chemical vapour deposition (CVD) grown nanocrystalline diamond is an
attractive material for the fabrication of devices. For some device
architectures, optimisation of its growth on silicon nitride is essential.
Here, the effects of three pre-growth surface treatments, often employed as
cleaning methods of silicon nitride, were investigated. Such treatments provide
control over the surface charge of the substrate through modification of the
surface functionality, allowing for the optimisation of electrostatic diamond
seeding densities. Zeta potential measurements and X-ray photoelectron
spectroscopy (XPS) were used to analyse the silicon nitride surface following
each treatment. Exposing silicon nitride to an oxygen plasma offered optimal
surface conditions for the electrostatic self-assembly of a hydrogen-terminated
diamond nanoparticle monolayer. The subsequent growth of boron-doped
nanocrystalline diamond thin films on modified silicon nitride substrates under
CVD conditions produced coalesced films for oxygen plasma and solvent
treatments, whilst pin-holing of the diamond film was observed following RCA-1
treatment. The sharpest superconducting transition was observed for diamond
grown on oxygen plasma treated silicon nitride, demonstrating it to be of the
least structural disorder. Modifications to the substrate surface optimise the
seeding and growth processes for the fabrication of diamond on silicon nitride
devices
Evaluating the coefficient of thermal expansion of additive manufactured AlSi10Mg using microwave techniques
In this paper we have used laser powder bed fusion (PBF) to manufacture and characterize metal microwave components. Here we focus on a 2.5âŻGHz microwave cavity resonator, manufactured by PBF from the alloy AlSi10Mg. Of particular interest is its thermal expansion coefficient, especially since many microwave applications for PBF produced components will be in satellite systems where extreme ranges of temperature are experienced. We exploit the inherent resonant frequency dependence on cavity geometry, using a number of TM cavity modes, to determine the thermal expansion coefficient over the temperature range 6â450âŻK. Our results compare well with literature values and show that the material under test exhibits lower thermal expansion when compared with a bulk aluminium alloy alternative (6063)
Evaluating the coefficient of thermal expansion of additive manufactured AlSi10Mg using microwave techniques
In this paper we have used laser powder bed fusion (PBF) to manufacture and characterize metal microwave components. Here we focus on a 2.5âŻGHz microwave cavity resonator, manufactured by PBF from the alloy AlSi10Mg. Of particular interest is its thermal expansion coefficient, especially since many microwave applications for PBF produced components will be in satellite systems where extreme ranges of temperature are experienced. We exploit the inherent resonant frequency dependence on cavity geometry, using a number of TM cavity modes, to determine the thermal expansion coefficient over the temperature range 6â450âŻK. Our results compare well with literature values and show that the material under test exhibits lower thermal expansion when compared with a bulk aluminium alloy alternative (6063)
Superconducting boron doped nanocrystalline diamond microwave coplanar resonator
A superconducting boron doped nanocrystalline diamond (B-NCD) coplanar
waveguide resonator (CPR) is presented for kinetic inductance () and
penetration depth () measurements at microwave frequencies of
0.4 to 1.2 GHz and at temperatures below 3 K. Using a simplified effective
medium CPR approach, this work demonstrates that thin granular B-NCD films
( 500 nm) on Si have a large penetration depth
( to 4.4 m), and therefore an associated high
kinetic inductance ( 670 to 690 pH/). These
values are much larger than those typically obtained for films on single
crystal diamond which is likely due to the significant granularity of the
nanocrystalline films. Based on the measured Q factors of the structure, the
calculated surface resistance in this frequency range is found to be as low as
2 to 4 at K, demonstrating the potential for
granular B-NCD for high quality factor superconducting microwave resonators and
highly sensitive kinetic inductance detectors.Comment: First draf
Quantitative analysis of the interaction between a dc SQUID and an integrated micromechanical doubly clamped cantilever
We provide simulations to quantitatively describe the interaction between a dc superconducting quantum interference device (SQUID) and an integrated doubly clamped cantilever. The simulations have been performed using the SQUID equations described by the resistively and capacitively shunted junction model coupled to the equation of motion of a damped harmonic oscillator. We have chosen to investigate an existing experimental configuration and have explored the motion of the cantilever configuration and the reaction of the SQUID as a function of the voltage flux V(ÎŚ)
V(ÎŚ)
characteristics. We clearly observe the Lorentz force back-action interaction and demonstrate how a sharp transition state drives the system into a nonlinear-like regime and modulates the cantilever displacement amplitude, simply by tuning the SQUID parameters
Blue delayed luminescence emission in neutral nitrogen vacancy containing chemical vapor deposition synthetic diamond
Herein, the authors investigate the temperatureâdependent properties of delayed luminescence in an asâgrown nitrogenâcontaining chemical vapor deposition synthetic diamond gemstone when excited above its bandgap. At room temperature, this gemstone exhibits delayed luminescence from nitrogenâvacancy centers at 575 nm. However, at 77 K, the first recorded instance of a longâlived delayed blue luminescence centered at â465 nm, accompanied by spectral peaks at 419, 455, and 499 nm is reported. By analyzing spectral and temporal data at different temperatures, it can be speculated on potential photophysical transitions. This discovery documents the initial observation of this delayed luminescence emission, contributing to the collective understanding of synthetic diamonds
Superconductivity in planarised nanocrystalline diamond films
Chemical vapour deposition (CVD) grown boron-doped nanocrystalline diamond (B-NCD) is an attractive material for the fabrication of high frequency superconducting nanoelectromechanical systems (NEMS) due to its high Youngâs modulus. The as-grown films have a surface roughness that increases with film thickness due to the columnar growth mechanism. To reduce intrinsic losses in B-NCD NEMS it is crucial to correct for this surface roughness by polishing. In this paper, in contrast to conventional polishing, it is demonstrated that the root-mean-square (RMS) roughness of a 520 nm thick B-NCD film can be reduced by chemical mechanical polishing (CMP) from 44.0 nm to 1.5 nm in 14 hours without damaging the sample or introducing significant changes to the superconducting transition temperature, , thus enabling the use of B-NCD films in the fabrication of high quality superconducting NEMS
Surface zeta potential and diamond growth on gallium oxide single crystal
In this work a strategy to grow diamond on β-Ga2O3 has been presented. The Îś-potential of the β-Ga2O3 substrate was measured and it was found to be negative with an isoelectric point at pH 4.6. The substrates were seeded with mono-dispersed diamond solution for growth of diamond. The seeded substrates were etched when exposed to diamond growth plasma and globules of gallium could be seen on the surface. To overcome problem 100 nm of SiO2 and Al2O3 were deposited using atomic layer deposition. The nanodiamond seeded SiO2 layer was effective in protecting the β-Ga2O3 substrate and thin diamond layers could be grown. In contrast Al2O3 layers were damaged when exposed to diamond growth plasma. The thin diamond layers were characterised with scanning electron microscopy and Raman spectroscopy. Raman spectroscopy revealed the diamond layer to be under compressive stress of 1.3â2.8 GPa