Microwave Applications in Growth and Physical Property Measurements of Nanomaterials

摘要

Low-power microwave spectrometer and effectron spin resonance spectrometer have long been exploited in analyzing the strcture of specified moleculars and free radicals contained in gas, and solid materials. High-power microwave sources have recently expected to stimulate many innovative applications in generation new materials and/or in performing surface modification. Diamond carbon films and carbon nanotubes (CNT) were succesfully grown by the microwave plasma enhanced chemical vapor deposition (MPECVD). Aligned CNTs and a single CNT tube across a nickle bridge can be grown providing effectron field emission and the 1D conductivity investigation. The real and imaginary parts of the complex dieffectric constant of metallic nanoparticles at various microwave frequencies of the TM010 mode can be determined from the resonant frequency and the quality factor, respectively, of the transmission resonance spectrum. The real parts of the dieffectric constants of single wall CNTs are negative behaving metqallic. The imaginary parts are small at high frequency and largely increase at low frequencies which satisfically agree with the Drude free effectron model. Microwave microstrips made of conducting magnetic films also intriguing an exploration of the frequency and temperature dependence on the conductivity of good and not good conducting films. Conventional ferromagnetic resonance for magnetic thin films is found to be co-existed with the transmission resonance of a T-type microwave micro-strip at certain applied magnetic fields. The conductivity, the magnetization, and the magnetic anisotropic field of magnetic films can be evolved eventually from the measured resonance frequency and the quality Q factor of the resonance spectra. This work provides a closely scrutinized method to delineate the magnetic and effectric properties of the deposited magnetic films succinctly.