Monoatomic tantalum induces ordinary-pressure phase transition from graphite to n-type diamond

It is a key challenge to synthesize large-area n-type diamond, which significantly obstacles its application in electronic devices. Here we find that monoatomic tantalum (Ta) lets graphite transform to diamond under normal pressure, subverting the common sense that this transition needs high temperature and high pressure, opening an era for preparing large-area diamond based on large-sized graphite. This phase transition removes non-diamond component in grain boundaries forming closely-packed nanocrystalline diamond films and ter-minates the grains by Ta, producing high mobility n-type conductivity. First principle calculations reveal that Ta supplies electrons to the adjacent graphene layer, transforming sp(2) electronic configuration to sp(3) state with energy barrier of-5.38 eV/unit cell. Ta terminated diatomic layer diamond forms a shallow donor energy level of ~0.4 eV. This supplies important significance in the fabrication of diamond-based electronic devices and gives a way for the sp(2)/sp(3) hybridized matter to realize the phase transition under ordinary pressure.

Automated summary

Monoatomic tantalum is capable of transforming graphite to diamond under normal pressure, enabling the preparation of large-area diamond films with high mobility n-type conductivity. This discovery has significant implications for the fabrication of diamond-based electronic devices.