Defect-induced electronic conduction of tBN thin films

摘要

Two kinds of turbostratic boron nitride (tBN) thin films were deposited by sputtering with pure Ar or N_2 plasma in an ultraclean vacuum chamber. Current-voltage (I-V) characteristics of Ti/tBN/Ti structures revealed that films deposited in Ar showed at least three-orders higher conductivity with strong temperature and electric field dependence compared with those deposited in pure N_2. The origin of the higher conductivity was confirmed to be the nonstoichiometry and higher defect density of the tBN films. On the other hand, films deposited in pure N_2 plasma showed the characteristics of intrinsic insulator even though the basal plane of tBN was oriented normal to the substrate, namely, parallel to the direction of electronic conduction.