Monolithic n-type conductivity on low temperature grown freestanding ultrananocrystalline diamond films

We report monolithic n-type conductivity on low-temperature (< 570 degrees C) grown ultrananocrystalline diamond (UNCD) films by Li-diffusion (about 255 nm) from LiNbO(3) substrates. Low resistivity of 1.2 Omega cm with carrier concentration of -2 x 10(20) cm(-3) is obtained on freestanding UNCD films. The films bonded to Cu-tape show very low turn-on field of 4.2 V/mu m with emission current density of above 0.3 mA/cm(2) at a low applied filed of 10 V/mu m. The n-type conductivity of low-temperature Li-diffused UNCD films overwhelms that of the high-temperature (>= 800 degrees C) nitrogen doped ones and will make a significant impact to diamond-based electronics. (C) 2010 American Institute of Physics. [doi:10.1063/1.3472204]