X-ray photoelectron spectroscopy of Ni doped boron carbides

Ni acts as an n-type dopant for semiconducting boron carbide (BC). A series of samples with increased Ni doping were grown on Si substrates using plasma enhanced chemical vapor deposition (PECVD) and characterized using IV measurements and X-ray photoelectron spectroscopy (XPS). Increased Ni doping leads to a linear increase in Ni concentration as evidenced by the intensity of the Ni 2p photoemission peak relative to that of the B 1s peak; concomitantly, the IV curves indicate that the BC becomes increasingly n doped. B1s peak shapes shows B-C and B-B bonding structure, and the C1s peak shows B$_{11}$C icosahedra bonds and C-B-C chain bonds in all samples. The overall binding energies for B and C agree with the results from sputter deposited stoichiometric B$_{4}$C [1]; in these PECVD grown samples, however, the graphite peak commonly seen in the sputter deposited B$_{4}$C is absent. [1] I. Jimenez, L. J. Terminello, \textit{et al.} J. Elect. Spec. Relat. Phenom., 101-103, 611-615 (1999).