Two-dimensional ambipolar carriers of giant density at the diamond/cubic-BN(111) interfaces: toward complementary logic and quantum applications

The extremely difficult ambipolar doping activation greatly hinders the outstanding performance of diamond for electronic devices. The main concern has been devoted to surface conduction by two-dimensional (2D) carriers. 2D hole gas (2DHG) in the diamond is induced by surface transfer doping dominated by the adsorbate's status and faces stability issues. Meanwhile, a feasible way to generate the other essential ambipolar carrier—2D electron gas (2DEG) is still lacking. We propose that the well-lattice-matched diamond/cBN(111) interfaces can spontaneously induce 2D ambipolar carriers with a giant density of 4.17 × 1014 cm−2, an order higher than other competitors. 2DEG and 2DHG can be separately achieved near the hetero-interfaces consisting of C–N and C–B bonds, respectively. Interestingly, the robust 2D charges are derived from a novel bulk-induced polarization-discontinuity at the interfaces, which can be attributed to an unexpected non-zero formal polarization of centrosymmetric cBN along the [111] direction. The existence of 2D ambipolar carriers at the diamond/cBN(111) interfaces has resolved the missing n-type conduction in diamond, thus opening up possibilities for complementary logic applications. Additionally, the high density of quantum-confined 2D ambipolar carriers provides an excellent platform for strongly correlated systems, which could lead to novel quantum information processing applications.