Effect of nitrogen on the electrical properties and growth mechanism of phosphorus-doped diamonds

De-nitrogen-doped phosphorus and nitrogen-phosphorus co-doped diamond single crystals were synthesized using the high pressure and high-temperature (HPHT) method at 6.0 GPa and 1450-1510 degrees C. The synthesis process was catalyzed using Fe80Ni20 as the catalyst of choice. The optical, mechanical, and electrical properties of the crystals were characterized. The effect of nitrogen atoms inside the diamond on a phosphorus-doped diamond was explored. The color of the diamond gradually became lighter with increasing Ti content, while the color of the crystal changed from yellow to dark green with increasing NaN3 content, and a large number of growth stripes and pits appeared on the surface. The infrared test showed that the addition of Ti reduced the concentration of nitrogen atoms inside the diamond, and the concentration of nitrogen atoms gradually increased with the addition of NaN3. Raman tests showed that the addition of Ti and NaN3 negatively affected the crystal quality. The X-ray photoelectron spectroscopy showed that phosphorus was successfully introduced into the diamond lattice in the form of CP and PO bonds under the conditions of nitrogen removal and nitrogen doping. Electrical tests showed that an n-type semiconducting diamond was successfully synthesized. However, the increase in nitrogen negatively affected the n-type conductivity.