Cubic Boron Nitride on Semiconducting Diamond and its Application to Neutron Detection

We have successfully deposited cubic boron nitride (c-BN) on nitrogen doped, polycrystalline diamond and boron doped, single crystal diamond, using plasma enhanced chemical vapor deposition (PECVD) employing fluorine chemistry. In situ X-ray photo spectroscopy (XPS) was utilized to characterize the sp³ bonding structure of c-BN. Cubic boron nitride is the zinc-blende analog to diamond, which is now being considered as an ideal material for radiation detection. TEM measurements demonstrate local epitaxy for c-BN on polycrystalline diamond. Boron containing materials are particularly relevant to detecting neutrons because of their large cross section to neutron capture and alpha particle emission. Moreover, diamond and c-BN have similar lattice constant and optical band gap which enables an integrated detector design. We present an approach to deposit c-BN on the p-type layer of a PIN diamond device in order to create a neutron detector. With the similar structural and outstanding thermal properties of c-BN and diamond, these devices can be used in a variety of applications, including high temperature environments.