Synthesis and characterization of molecularly doped nanodiamond at high pressure and high temperature conditions*

The ability to optically initialize, manipulate, and read out the spin of defects in diamond has enabled multifunctional applications in quantum computing, sensing, and cryptography. However, the rational doping of nanodiamond has remained a challenge due to diffusion limitations and diamond’s metastable lattice.

Here, we present a new bottom-up method to create doped nanodiamond via molecular dopant molecules added into an amorphous, hydrocarbon matrix. At high pressure, high temperature conditions in a laser heated diamond anvil cell, the amorphous carbon doped with silicon and nitrogen molecules converts to doped nanocrystalline diamond containing silicon and nitrogen defects. At elevated pressures, photoluminescence, lifetime, and Raman measurements monitor the incorporation of dopants and formation of diamond. Electron energy loss and energy dispersive X-ray spectroscopies of the recovered samples further demonstrate nanocrystalline diamond formation and molecular doping. Photothermal heating models elucidate the critical role of the pressure media during diamond formation.