Diamond offers a set of characteristics that make it an interesting choice for a wide range of applications. It has the highest known thermal conductivity, is chemically un-reactive and is the hardest known material. It also has a wide (5.5eV) indirect bandgap meaning it has a high breakdown voltage.
As a substrate for high power devices it is robust, lightweight and able to transfer heat from the active region better than any other material whilst tolerating high applied voltages.
It is a suitable replacement for silicon in MEMS devices where wear and bio-compatibility are a concern and can be combined with piezo-electric materials like AlN to form high frequency SAW devices. Its optical absportion is low across the visible spectrum, which combined with a high refractive index allows it to be used for applications like waveguiding.
The leading candidate for quantum information processing, where NV centres can be interrogated to give information about the quantum states.