Laboratory and facilities

 

Cardiff Diamond Foundry operates four Microwave Plasma Chemical Vapour Deposition systems. Our main doping workhorse is a Seki 6500 series system equipped with Trimethylboron as the doping source. This reactor routinely grows superconducting diamond films with transition temperatures around 5K as well as electrochemical electrode grade material. A second load-locked UHV system (Seki SDS5250) is being installed  for our SQUIDs and superconducting nanoelectromechanical systems.


For intrinsic diamond growth we operate a Carat Systems CTS6U which is basically an enhanced 6500 series with differentially pumped seals and conflat windows. It has a far lower leak rate than a standard 6500 reactor.


Our fourth reactor is a home built quartz tube (NIRIM) style reactor. This system is for the production of diamond with novel colour centres. We openly share the design of this system to other users. This system has a liquid precursor option for incorporating novel materials into the CVD process.


All reactors have comprehensive in-situ monitoring including pyrometers covering the temperature ranges 200-600ºC, 300-1000ºC and 475-1475ºC. These are two colour ratio pyrometers which have been calibrated and demonstrated their accuracy on numerous substrates. However, the use of pyrometry is fraught with dangers and their accurate use requires some skill and experience.


Growth rates can be monitored in-situ either by laser interferometry (for films thicker than 100nm) or by Spectroscopic Ellipsometry (films from 10nm thick).


All deposition equipment is fully automated with safety systems that allow long term unsupervised operation with process logging.


Nucleation areas are entirely under (class 100) lamina flow to reduce contamination from dust particles etc. Substrates are immersed in aqueous colloids of mono-disperse diamond particles under ultrasound. After this they are rinsed and spun dry with a wafer spinner. These techniques have been demonstrated to yield the ultra-high nucleation densities required for nanocrystalline diamond growth.


For post growth planarisation, the laboratory is equipped with a Logitech Tribo Chemo-Mechanical Polishing facility. Processes to planarise nanocrystalline diamond films from their as grown roughness of the order of 20 nm rms (over several micron) down to below 2nm rms have been developed in collaboration with Logitech Ltd. This process is based around Syton SF1 slurry (colloidal silica). This process has been demonstrated to be effective on both nanocrystalline diamond and single crystal materials ({100} and {111}).


The nanoparticles purification facility is based around a high vacuum furnace with the capability of annealing in hydrogen, oxygen, nitrogen, argon or vacuum at temperatures up to 1200 °C. This chamber also has optical access and can exploit two high power lamps, a 400W Xenon broadband lamp and a 30W Deuterium UV source. Dispersal of purified nanodiamond particles can be achieved by a high power ultrasonic probe (Sonics VCX500 500W).


Recently, a high power planetary mill (Pulverisette 7 Premium Line) has been added to the nanoparticle suite. This apparatus allows the milling of bulk diamond films into nanoparticles. Combined with the CVD facilities, the production of custom nanodiamond particles with controlled impurities such as silicon, nitrogen, boron etc is possible.

Seki 6500 series Microwave Plasma Chemical Vapour Deposition system for diamond growth (boron doping).

Logitech Tribo Chemo-Mechanical Polishing (CMP) system for planarising wafers up to 4” diameter.

High vacuum furnace / annealing chamber with H2 / O2 / Ar / N2 gas lines and UV light facilities.

Carat Systems CTS6U deposition system for high purity intrinsic diamond.

High G (>60KG RCF) centrifuge and planetary mill for nanoparticle production and purification