Semiconducting cubic boron nitride

We present new developments in the preparation of semiconducting cubic boron nitride. The thin films were grown on (100) silicon substrates using electron cyclotron resonance (ECR) ion-assisted magnetron sputtering with the kinetic energy of the incident nitrogen ions controlled by a de substrate bias. Using this technique we have been able to grow thick (up to 2 mu m) boron nitride films containing 100% of the cubic phase. We have found that the relatively high nitrogen ion energy (similar to 100 eV), required to nucleate the cubic phase, can be reduced substantially (to similar to 60 eV) once the cubic phase is formed, leading to reduced film stress, larger grain size (similar to 1000 Angstrom) and improved adhesion. The films have p-type conductivity, The carrier activation energy is 60 meV and we have observed Hall mobilities of 500 cm(2) V-1 s(-1) at n(a) approximate to(5 x 10(18) cm(-3)). (C) 1998 Elsevier Science S.A.