We have nickel doped baron carbide grown by plasma enhanced chemical vapor deposition. The source gas closo-1,2-dicarbadodecaborane (ortho-carborane) was used to grow the boron carbide, while nickelocene [Ni(C5H5)(2)] was used to introduce nickel into the growing him. The doping of nickel transformed a p-type, B5C material, relative to lightly doped n-type silicon, to an n-type material. Both n-n heterojunction diodes and n-p heterojunction diodes were constructed, using as substrates n- and p-type Si(111), respectively. With sufficient partial pressures of nickelocene in the plasma reactor, diodes with characteristic tunnel diode behavior can be successfully fabricated.