A high-dielectric constant (high-k) TiO x thin layer was fabricated on hydrogen-terminated diamond (H-diamond) surface by low temperature oxidation of a thin titanium layer in ambient air. The metallic titanium layer was deposited by sputter deposition. The dielectric constant of the resultant TiO x was calculated to be around 12. The capacitance density of the metal-oxide-semiconductor (MOS) based on the TiO x /H-diamond was as high as 0.75 µF/cm 2 contributed from the high-k value and the very thin thickness of the TiO x layer. The leakage current was lower than 10-13 A at reverse biases and 10-7 A at the forward bias of-2 V. The MOS field-effect transistor based on the high-k TiO x /H-diamond was demonstrated. The utilization of the high-k TiO x with a very thin thickness brought forward the features of an ideally low subthreshold swing slope of 65 mV per decade and improved drain current at low gate voltages. The advantages of the utilization high-k dielectric for diamond MOSFETs are anticipated.

The impedance spectroscopy measurements were used to investigate the separated contributions of diamond grains and grain boundaries (GBs), giving an insight of p-type to ntype conductivity conversion in O + -implanted ultrananocrystalline diamond (UNCD) films. It is found that both diamond grains and GBs promote the conductivity in O + -implanted UNCD films, in which GBs make at least half contribution. The p-type conductivity in O + -implanted samples is a result of H-terminated diamond grains, while n-type conductive samples is closely correlated to O-terminated O + -implanted diamond grains and GBs in the films. The results also suggest that low resistance of GBs is preferable to obtain high mobility n-type conductive UNCD film.

Impedance spectroscopy (IS) analysis is carried out to investigate the electrical properties of the metal-oxide-semiconductor (MOS) structure fabricated on hydrogen-terminated single crystal diamond. The low-temperature atomic layer deposition Al 2 O 3 is employed as the insulator in the MOS structure. By numerically analysing the impedance of the MOS structure at various biases, the equivalent circuit of the diamond MOS structure is derived, which is composed of two parallel capacitive and resistance pairs, in series connection with both resistance and inductance. The two capacitive components are resulted from the insulator, the hydrogenated-diamond surface, and their interface. The physical parameters such as the insulator capacitance are obtained, circumventing the series resistance and inductance effect.By comparing the IS and capacitance-voltage measurements, the frequency dispersion of the capacitance-voltage characteristic is discussed. a)

We have investigated the structural and electrical properties of carbon ion implanted ultrananocrystalline diamond (UNCD) films. The impedance spectroscopy measurements show that impedance value of diamond grains is relatively stable, while that of grain boundaries (R b) dramatically increases after C + implantation and decreases as annealing temperature (T a) increases from 650 to 1000 o C. This means that C + implantation has more significant impact on the conductivity of grain boundaries (GBs). Conductive atomic force microscopy results evidence that the number of conductive sites increases in GB regions at T a above 900 o C, which is originated from the formation of nanographitic phase confirmed by high resolution transmission electronic microscopy. Visible Raman spectra show that resistive trans-polyacetylene oligomers desorb from GBs at T a above 900 o C, which also results 

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Lanthanum-doped bismuth titanate (BLT) thin films were grown on buffered Si substrates using a RF magnetron sputtering system. Electrically conducting ZnO layers were used as an effective buffer layer to facilitate the growth of the ferroelectric thin films. X-ray diffraction data shows the Aurivilius phase structure with the highest diffraction peak (117), indicating non-c-axis-oriented microstructure. Random oriented plate-like grains were observed using scanning electron microscopy. The ferroelectric nature of the film was proved by ferroelectric domain switching under an electrical field.