Synthesis and properties of n-type semiconductor diamond crystals synthesized via the addition of Fe3P to the Fe-C-P system under HTHP conditions

In this paper, we report the synthesis of phosphorus-doped diamond using the China-type large volume cubic high-pressure apparatus under the Fe-C-P system with Fe3P added using Fe as a catalyst at 6 GPa and 1400-1500 degrees C. The characterization results show that the increase in Fe3P addition not only causes pits and growth streaks on the crystal surface. But also leads to an increase in the internal stress of the crystals and also decreases the crystallinity of the crystals. With the increase of Fe3P addition, the C-center nitrogen content increases slowly, but the whole C-center nitrogen content remains at a low level. Phosphorus atoms enter the diamond lattice to form P-C and P-O bonds with C and O. The synthesized crystals have n-type conductivity with resistivity up to 8.09 x 105 and Hall's coefficient of -8.82 x 108. It has been demonstrated that Fe as a catalyst is beneficial for the synthesis of diamond crystals with higher quality and can effectively reduce the entry of impurities into the synthesis system. Comparison of the performance of diamond synthesized with different additives demonstrated that phosphides are better additives for synthesizing n-type semiconductor diamonds. The Fe-C-P system constructed by adding Fe3P to Fe as catalyst is suitable for the synthesis of n-type semiconducting diamonds. This study provides insights into the construction of novel systems for synthesizing n-type semiconducting diamonds and emphasizes the important influence of additives and catalyst selection on diamond properties.