ELECTRICAL CHARACTERIZATION OF AL SI OHMIC CONTACTS TO HEAVILY BORON-DOPED POLYCRYSTALLINE DIAMOND FILMS/

Mesa etched transmission line model (TLM) test structures with differe nt contact lengths have been fabricated on heavily boron doped polycry stalline diamond films. The behavior of the contact and contact end re sistance measurements can be fully explained using the TLM. No influen ce of the grain size on the contact resistivity has been observed. Hig h surface boron doping concentrations led to low contact resistivities , in agreement with numerical calculations. Annealing of Al/Si-diamond contacts at 450 degrees C in N-2 leads to lower contact resistivities due the formation of SiC at the metal-diamond interface. The temperat ure dependence of the specific contact resistivity can be described we ll with a tunneling model before annealing. After annealing no useful fit is possible, indicative of the fact that the SIC interface layer a cts as defect layer. (C) 1996 American Institute of Physics.