We have successfully nickel doped a boron carbide (B5C) alloy film. The nickel doped boron-carbide (Ni-B5C1+&dgr;)thin films were fabricated from a single source carborane cage molecule and nickelocene [Ni(C5H5)2] using plasma enhanced chemical vapor deposition. Nickel doping transforms the highly resistive undoped film from ap-type material to ann-type material. This has been verified from the characteristics of diodes constructed of Ni-B5C1+&dgr;on bothn-type silicon andp-type B5C. The homojunction diodes exhibit excellent rectifying properties over a wide range of temperatures. ©1997 American Institute of Physics.