n-type conductivity and phase transition in ultrananocrystalline diamond films by oxygen ion implantation and annealing

Abstract

Ultrananocrystalline diamond (UNCD) films were implanted by oxygen ion and annealed at different temperatures. The electrical and structrual properties of O+-implanted UNCD films were investigated by Hall effects, high-resolution transmission electron microscopy (HRTEM) and uv Raman spectroscopy measurements. The results show that O+-implanted nano-sized diamond grains annealed at 800 °C and above give n-type conductivity to the sample and the UNCD film exhibits n-type resistivity with the carrier mobility of 1∼11 cm2 V−1s−1. With O+ dose increasing from 1015 to 1016 cm−2, diamond phase transits to the amorphous carbon phase accompanied by n-type semiconduction transforming to metallic conduction. In the 1014 cm−2 O+-implanted UNCD film, some amorphous carbon at grain boundaries transits to diamond phase with annealing temperature (Ta) increasing from 500 °C to 800–900 °C, and some of diamond grains are found to be converted to amorphous carbon phase again after 1000 °C annealing. This phase transition is closely relative to the n-type conductivity of the UNCD films, in which n-type conductivity increases with the amorphous carbon phase transiting to diamond phase in the Ta range of 500–900 °C, and it decreases with diamond phase transiting to amorphous carbon phase in the case of 1000 °C annealing. It is indicated that the O+-implanted nano-sized diamond grains dominantly control the n-type conductivity of UNCD film in the Ta range of 800–900 °C, while the grain-boundary-conduction controls the n-type conductivty in UNCD film annealed at 1000 °C. In this case, a novel conduction mechanism that O+-implanted nano-sized diamond grains supply n-type conductivity and the amorphous carbon grain boundaries give a current path to the UNCD films is proposed.

Self-assembled ultrathin nanotubes on diamond (100) surface

“…6). On the other hand, n-type conductive ultrananocrystalline diamond films prepared under hydrogen-poor conditions have achieved high electron mobility via oxygen ion doping 33 . The transport of electrons on a dimer surface is highly anisotropic, with the conductivity being much lower than that of our tube array surface, as implied by their band dispersions and calculated effective masses (Supplementary Fig.…”

The microstructural evolution of ultrananocrystalline diamond films due to P ion implantation and annealing process-dosage effect

“…On the other hand, ion implantation has long been utilized to amend the properties of materials through controlled doping, using select dopants [14][15][16][17]. Recent reports show that oxygen and phosphorous ion implantation result in the n-type conductivity of the UNCD films [16,17]. But the possible contribution on the electrical properties of the films related to the modification of granular structure has not been well explained yet.…”

“…[10][11][12][13] However, N 2 incorporation via the addition of N 2 gas to the growth plasma requires high growth temperature (700°C) [13]. On the other hand, ion implantation has long been utilized to amend the properties of materials through controlled doping, using select dopants [14][15][16][17]. Recent reports show that oxygen and phosphorous ion implantation result in the n-type conductivity of the UNCD films [16,17].…”

The microstructural evolution of ultrananocrystalline diamond films due to P ion implantation process—the annealing effect

“…13 On the other hand, ion implantation has long been utilized to amend the properties of materials through controlled doping, using select dopants. [14][15][16][17] Recent reports show that oxygen and phosphorous ion implantations result in n-type conductivity of UNCD films. 16,17 But the possible cause for such a modification of the granular structure has not been well explained yet.…”