Synthetic diamond grown by chemical vapor deposition (CVD) continues to prove its worth as a key material driving innovation across a wide variety of industries, including optics and photonics, wastewater treatment electronics and semiconductors, as well as emerging fields such as quantum physics and magnetic imaging. Element Six specializes in the development and production of diamond-based products, carefully manipulating unique characteristics—such as strength and durability, thermal conductivity, optical transmission, electrochemical sensitivity and electrical resistivity—to create solutions perfectly suited to address the most demanding of engineering challenges. This article details how the latest synthetic diamond product innovations are being applied to a variety of industrial processes with dramatic end user benefits such as reduced downtime, system miniaturization and increased reliability.
Enabling extreme performance in optics
Element Six single crystal CVD diamond has been instrumental in providing solutions that previously have been unattainable in optical settings, such as infrared (IR) spectroscopy and novel laser technologies. For example, researchers at MQ Photonics Research Centre at Macquarie University in Australia have demonstrated a laser leveraging specifically engineered low absorption single crystal CVD diamond that is 20 times more powerful than previous Raman laser systems. To put this into perspective, this laser has the output power of approximately 400,000 laser pointers, enough to cut through steel. This single crystal technology has led to more than 60 new patents being secured by Element Six in 2016 alone.
Element Six anticipates an increased demand for large area polycrystalline diamond optics in extreme ultraviolet (EUV) lithography as the industry prepares for high volume EUV-based manufacturing. Element Six’s Diamond PureOptics (shown above) offers engineers of the next generation of EUV systems a robust solution to the delamination problems associated with thin film anti-reflective (AR) coatings. Its coating-free AR technology provides an improved damage threshold at even higher powers, enabling reduced down time and increased productivity in high power transmissive optics. Available now for the CO2 laser wavelength 10.6 µm, Diamond PureOptics increases reliability by a factor of at least 10 over traditional AR coatings, even at continuous wave (CW) power densities up to 3 MW/cm2. Optical absorption is also decreased with a Diamond PureOptics window, reducing heat driven effects such as thermal lensing. Due to the chemically inert nature of diamond, this optical component can be easily and thoroughly cleaned using aggressive acids and solvents.
A simple solution for the toughest wastewaters
Synthetic diamond is chemically and biologically inert, so it can survive in harsh physical and chemical environments that severely damage other materials—a robustness well suited to tackling highly toxic wastewaters. Free standing boron doped diamond (BDD) is an ideal electrode material to electrochemically convert toxic organic pollutants to inert byproducts. This material is the fundamental technology behind Element Six’s DIAMOX electrochemical advanced oxidation cell (shown here) for industrial wastewater treatment.
In a recent oil and gas refinery wastewater treatment trial using DIAMOX, sulfur compounds were undetectable in the treated effluent and the concentration of dissolved organic pollutants was reduced by more than 95 percent. As demand for innovative treatment solutions increases within the water industry, DIAMOX is poised to deliver value across applications as diverse as pharmaceutical wastewater, textile dye-house wastewater, landfill leachates and refinery waste effluents.
Competitive advantage in electronics/semiconductors
With the highest known bulk thermal conductivity, synthetic diamond is the ideal material for handling the growing thermal demands of the semiconductor industry. Considering 50 percent of electronic system failures occur due to heat-related issues, CVD diamond is beneficial in all types of electronic and electrical applications. Element Six has already developed a range of synthetic diamond thermal grades and an advanced metallization scheme to further exploit the heat management properties of diamond. In June 2017, Element Six introduced the first electrically conductive CVD diamond heat spreader, Diafilm ETC700, which delivers exceptional heat dissipation combined with minimal resistive and RF losses. The material is uniquely suited to effectively manage heat in high frequency, high power density devices. The company will continue building upon learnings from its recently completed fundamental thermal management program supported by Defense Advanced Research Projects Agency (DARPA) to help further advance the semiconductor industry. As performance metrics and size reduction continue to drive power density increases in electronic components and sub-systems, synthetic diamond enables reductions in device temperature, delivering improved reliability and performance.
Sounds like a diamond
Diamond is also unique in that it can be grown on non-planar surfaces producing free-standing curved films and diaphragms—ideally suited for a wide variety of applications, including audio. For more than a decade, Element Six has partnered with world leading loudspeaker manufacturer Bowers & Wilkins to provide a volume manufacturing technology for curved free-standing thin film polycrystalline diamond diaphragms just 40 microns thick.
This material is perfect for tweeter domes, reproducing high frequency sound without distortion.
Thanks to recent R&D developments and working in partnership with leading academic organizations in Europe and the U.S., Element Six’s synthetic diamond is enabling new applications by manipulation of quantum spins. Synthetic diamond can be engineered to contain “nitrogen vacancy (NV) centers,” each consisting of a single nitrogen atom adjacent to a missing carbon atom. This NV center can be used as a quantum bit—or qubit— whose quantum properties are remarkable in that they can be manipulated and read out at room temperature. The ability to manipulate quantum information at room temperature is a valuable property of diamond. In nearly all other approaches to using quantum physics to enable new technologies, heat energy in the crystal lattice quickly scrambles any quantum information, necessitating the use of cryogenic temperatures. Diamond’s strongly-bonded crystal structure means that the crystal lattice does not interact strongly with the NV qubits, hence the delicate quantum properties are maintained even at room temperature.
With the control of nano-engineering using CVD techniques, synthetic diamond can be produced in exceptionally pure form. It is this purity that places it at the heart of the many ground-breaking achievements in quantum physics that may have applications including sensing and quantum information processing. In sensing, for example, the direction and magnitude of an external magnetic field can be measured by the quantum spin of the NV defect. In the future, this technology could replace traditional brain imaging techniques used in MRI, which are limited by the sensitivity of the sensors. A diamond solution could provide greater sensitivity and resolution along with a greater degree of portability, which could open up new diagnostic and treatment methods.
Written by Dan Twitchen, CVD business development, Element Six