Plasma Chemical Vapour Deposition (PCVD) is a technique by which lab-growing diamonds can be grown from a hydrocarbon gas mixture. In the CVD process, a thin slice of diamond seed (often an HPHT-produced diamond) is placed in a sealed chamber at high temperature and high pressure. The chamber is then filled with a carbon-rich gas (usually methane) and other gases. Then, the gases are ionized into plasma using microwaves, lasers, or other techniques. The Ionisation breaks the molecular bonds in the gases, and the pure carbon adheres to the diamond seed and slowly builds up into a crystal, atom by atom and layer by layer form.
The method for producing a diamond includes positioning the diamond in a holder such that a thermal contact is made with a side surface of the diamond adjacent to an edge of a growth surface of the diamond, measuring the temperature of the growth surface of the diamond to generate temperature measurements, controlling the temperature of the growth surface based upon the temperature measurements and growing single crystal diamond by microwave plasma chemical vapor deposition on the growth surface, wherein the growth rate of the diamond is greater than 1μm per hour. In this whole process, temperature plays a very important role. We need to measure the temperature of the target diamond rather than the plasma.
Temperature Measurement by Infrared Pyrometers
A non-contact temperature measurement device is positioned to measure the diamond’s temperature across the diamond’s grown surface. The pyrometer is mounted on a glass window of a chamber to read the temperature of the target diamond. The challenging part of the application is Plasma emits IR energy at specific wavelengths, and we need to measure the consistent temperature of the target through the plasma. AST offers a Non-contact type IR-based Pyrometer, which works in selected wavelengths where plasma is transparent.
- Temperature Range – 350°C to 1800°C
- Fast response time in milliseconds
- Laser sighting
- Connectivity via USB 2.0, Bluetooth V2.0 and RS-232 or RS-485 Serial interface
- Measure the temperature of the target through the plasma at a specific wavelength