2019/10/21 by Tanvi Nikhar, Robert Rechenberg, Nikhar, Tanvi +5
Materials Science · Engineering · Physics and Astronomy · #Diamond and Carbon-based Materials Research #Advanced materials and composites #Force Microscopy Techniques and Applications
paper · pdf · doi:10.48550/arxiv.1910.09595
Detailed structural and electrical properties of ultra-nano-crystalline\ndiamond (UNCD) films grown in H_\2/CH_\4/N_\2 plasma\nwere systematically studied as a function of deposition temperature (Td) and\nnitrogen content ( % N2) to thoroughly evaluate their effects on\nconductivity. Td was scanned from 1000 to 1300 K for N2 fixed at 0, 5, 10\nand 20 %. It was found that even the films grown in the synthetic gas\nmixture with no nitrogen could be made as conductive as 1-10-2 \Ω\ncm with overall resistivity of all the films tuned over 4 orders of magnitude\nthrough varying growth parameters. On a set of 27 samples, Raman spectroscopy\nand scanning electron microscopy show a progressive and highly reproducible\nfilm material phase transformation, from ultra-nano-crystalline diamond to\nnano-crystalline graphite as deposition temperature increases. The rate of this\ntransformation is heavily dependent on N2 content. Addition of nitrogen\ngreatly increases the amount of sp2 bonded carbon in the films thus\nenhancing the physical connectivity in the GB network that have high electronic\ndensity of states. However, addition of nitrogen greatly slows down\ncrystallization of sp2 phase in the GBs. Therefore, proper balance between\nGB connectivity and crystallinity is the key in conductivity engineering of\n(N)UNCD.\n