Significant enhancement of electrical conductivity in boron-doped diamond through HPHT post-annealing treatment

Boron-doped diamond (BDD) is expected as a promising semiconductor candidate for potential application in next-generation high-power and high-voltage electronics. Unfortunately, a feasible strategy that focuses on the improvement of the semiconducting performance of BDD materials is still lacking and remains a fundamental challenge in material science. Thus, we aim to study the stability and adjustment behaviors of boron dopants in BDD single crystals through post-annealing treatment under high pressure and high temperature (HPHT) conditions. In this work, our study demonstrates that boron dopants show high structural stability, and no extra complex defects were observed during the HPHT annealing process, a superior advantage for the device application in extreme environments. Our work further reveals that the HPHT post-annealing process is effective to eliminate the intrinsic stress and local lattice strain that were inherently formed during the diamond growth process. This process is accompanied by the enhancement of ionization ratio of boron dopants. The carrier content of one 111-GS BDD increases by more than ten times after post-annealing at 1000 degrees C and 5.5 GPa, resulting in significant improvement of conductivity by a factor of 2. This result provides an effective strategy to improve the semiconducting performance of BDD materials through HPHT annealing approach and promote their practical device applications.