Su-Jien Lin

Effect of boron doping on the electron-field-emission properties of nanodiamond films

The electron-field-emission (EFE) behavior of the nanodiamond films was observed to be pronouncedly superior to that of the diamond films with micrometer- or submicrometer-sized grains, which is ascribed to the presence of abundant grains boundaries with sp2 bonds. Incorporation of boron species into the nanodiamond films further improves the EFE properties for the films. The best EFE properties achieved are turn-on field E0=18V∕μm with EFE capacity J=0.7mA∕cm2 at around 30V∕μm applied field. However, boron doping into the nanodiamond films does not result in consistent boron-content dependence of the EFE properties for the films as those in conventional micrometer-sized diamonds. The complication is explained by the fact that the small size of the diamond grains (∼20nm) may not be able to accommodate the boron species into the lattices to effectively act as acceptor dopants. Moreover, the formation of aggregates of the nanosized diamond grains may alter the local field enhancement factor, which further c...

Current image tunneling spectroscopy of boron-doped nanodiamonds

The electron field emission properties of the nanodiamond films were examined using scanning tunneling microscopic (STM) technique. Current image tunneling spectroscopic measurements reveal the direct dependence of electron tunneling/field emission behavior of the films on the proportion of grain boundaries present. Local tunneling current-voltage (It–V) measurements show that incorporation of boron species insignificantly alters the occupied state, but markedly modifies the empty state of the diamond films, viz. it induces the presence of impurity states for the films heavily doped with borons, resulting in smaller emission energy gap for the samples. Such a characteristic improves both the local electron field emission behavior of the diamond films measured by STM and the average electron field emission properties measured by conventional parallel plate setup. These results infer clearly that the presence of impurity states due to boron doping is a prime factor improving the field emission properties fo...

Low Loss Tunable Thick Films Based on (Ba,Sr)TiO3 and Ba4Ti13O30 Materials

Modification on microwave dielectric properties of (Ba0.6Sr0.4)TiO3 (BST) materials due to the incorporation of Ba4Ti13O30 (B4T13) materials was investigated. The dielectric constant of the BST materials was lowered from KBST = 600 to KCOMP = 100, whereas the quality factor of the materials was increased markedly from (Q ×} f)BST = 80 to (Q ×} f)COMP = 2,000, due to the addition of B4T13 materials. Evanescent microwave probe (EMP) measurements indicate that the thick films prepared from the mixture contain two phases. The low-K and high-Q particulates, which are presumably B4T13 phase, are distributed uniformly among the high-K and low-Q matrix, resulting in a tunable materials with improved microwave dielectric properties.

Growth Behavior of (Pr2/3Ca1/3)MnO3 Layer and the Buffering Effect on Pb(Zr, Ti)O3 Thin Films

Growth behavior of (Pr2/3Ca1/3)MnO3, PCMO, thin films deposited by pulsed laser deposition (PLD) process on uncoated or Pt-coated silicon substrates was investigated. Perovskite phase of PCMO thin films can be formed directly on Si-substrate only in a very narrow range of deposition parameters. Using PCMO thin films as buffer layer markedly enhances the crystallization kinetics for the subsequently grown Pb(Zr0.52Ti0.48)O3 (PZT) thin films, which were prepared by metallo-organic-deposition technique. The perovskite phase of PZT films can be obtained at lower post-annealing temperature (550°C) and sustain higher heat treatment temperature (700°C) without inducing significant degradation. The presence of PCMO-buffer layer markedly suppresses the leakage currently density for the PZT films, but insignificantly alters their ferroelectric properties.