Structural and electrical properties of CVD diamond films doped by N+ implantation

Chemical vapor deposited (CVD) diamond films (DF) were prepared on P-type <100> oriented Si substrates. The films were implanted with 140 keV N+ to doses of 5×1014∼1×1016cm−2, respectively. Under the implantation, the DF becomes more and more disordered with each increasing dose. Scanning electronic microscopy (SEM) and Raman measurements reflect the amorphization process. Combining the electrical resistance measurements, it is clear that polycrystalline DF has a higher threshold dose of amorphization than that for bulk ones. The damages induced by implantation can be partially removed by annealing when the dose is below the critical value. Larger doses of implantation produce amorphous carbon which can transform into micro-polycrystalline graphite during annealing. Thus, the conductivity is increased dramatically. However, for smaller dose N+ implanted samples, while annealing was performed, the samples become comparable conductive for the activation of N dopants.