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