Advances in diamond nanofabrication for ultrasensitive devices

Abstract

This paper reviews some of the major recent advances in single-crystal diamond nanofabrication and its impact in nano-and micromechanical, nanophotonics and optomechanical components. These constituents of integrated devices incorporating specific dopants in the material provide the capacity to enhance the sensitivity in detecting mass and forces as well as magnetic field down to quantum mechanical limits and will lead pioneering innovations in ultrasensitive sensing and precision measurements in the realm of the medical sciences, quantum sciences and related technologies. INTRODUCTIONDiamond is an ideal platform for nano-and microfabrication leading to a range of robust sensors. This is due to the outstanding mechanical and wide spectral optical transparency of diamond, combined with biocompatibility and lack of toxicity in both bulk and nanostructures. Moreover, diamond can be fabricated with high purity and control using chemical vapor deposition. However, due to its hardness and cost, some of its applications in nanomechanics, optomechanics and nanophotonics reside mainly in its polycrystalline or nanocrystalline forms, which do not always retain the nuance of the outstanding properties of monocrystalline diamond.A recent review 1 describes diamond optical and mechanical properties compared to other materials currently used for optomechanical components (Si, Si 3 N 4 , SiC, and α-Al 2 O 3 ), showing that, in principle, there are more favorable properties of diamond for nanomechanical and optomechanical realizations. Therefore, a considerable effort has been taking place over the last five years to exploit these properties in a wide spectrum of diamond nanosystems. To date, single crystal diamond utilization for nanomechanical components 2 , (for example, nano electromechanical systems (NEMS) and micro electro-mechanical systems (MEMS)), as well for nanophotonics 3,4 compared to above mentioned materials, has been limited due to its growth requirements. In fact, a single crystal diamond cannot be grown on any other substrate than itself. This prevents wafer-scale processing and it represents a challenge in the application of conventional diamond nanofabrication methods. On the other hand, polycrystalline diamond films, which can be grown in high quality from 4 to 6 inches' wafers 5 , permit to fabricate optomechanical components with quality factors and oscillation frequencies rivaling single crystal diamond 6 .

Emerging material systems for integrated optical Kerr frequency combs

“…The initial microring devices achieved Q factors in the 1 million range, which was moderate when compared with the other dielectric devices discussed thus far. [102,107,358] However, given diamond's higher linear and nonlinear refractive indices, the potential for generating frequency combs was clearly evident.…”

Nitrogen-vacancy centers in diamond for nanoscale magnetic resonance imaging applications

“…Recent advances in diamond fabrication for scanning tip magnetometry have been achieved by a functionalized ND with NV center magnetic spins scanned by attaching it to the tip of an atomic force microscope (AFM). This can also be achieved by mounting a high-purity diamond nanopillar on an AFM with an NV center placed 10 nm from its end, achieving a sensitivity of 56 nT·Hz −1/2 , as reported in [37].…”

Fast smoothing on diamond surface by inductively coupled plasma reactive ion etching

“…Moreover, a bulge in the position shown from 1430 cm -1 to 1580 cm -1 of the spectra could be probably attributed to the Raman active vibrational mode of sp 2 hybridized non-crystalline carbon on the etched surface [27,28]. As for the spectra of the diamond sample etched in O2+CF4 (PCD10), the bulge appeared more obvious, because of the accumulation of C on the surface and the contemporaneous slow etching rate [6,24]. However, owing to the inclusion of H atom in the CHF3, the broad peak of each Raman spectra on the diamond sample etched in O2+CHF3 (PCD7) almost disappeared, which resulted from the reaction as shown by equation (1).…”

“…Multiple parameters variation has been used to optimise the surface morphology and chemical reaction status of diamond during the ICP-RIE process [23]. So far, there are a number of reports on diamond nano-structuring and smoothing by ICP-RIE but there are few systematic studies of synergetic effect and optimisation of this etching method on diamond nor any accurate prediction of the etching results [6,[24][25]. Thus, the investigation of the effect and refining of ICP-RIE multifarious parameters on diamond including both SCDs and PCDs is extremely important.…”

“…Meanwhile, as shown in the 3D images, distinct and consistent patterns were presented. The masked area exhibited a rugged surface because the electron beam dissolved the aluminium layer that was too weak, amorphous and thin (100 nm) to protect the diamond from heavy ion bombardment[24]. As such, this area received uneven coverage under ion bombardment, negatively affecting the etching outcomes.…”