Pulsed-laser deposition (PLD) is a versatile technique for thin film deposition. The generation and propagation of laser-induced
plasmas have been extensively studied. Other plasma sources have been combined with PLD to improve the film
qualities. The knowledge about the interactions between the laser-induced plasmas and additional plasmas and their
effects on film growth is still limited. We have investigated the optical emission spectra from the interaction region of
low-pressure ECR microwave plasmas and pulsed-laser-induced plasmas. In this region, the spatial and temporal
distributions of the laser-ablated species were altered while very few collisions were expected in the ambient gas due to
the low pressure. The results were compared with those with laser ablation or ECR microwave discharge along. The
mechanisms and effects of the interactions were discussed.
We have prepared carbon nitride thin films by using plasma assisted pulsed laser deposition. In this method, a graphite target was ablated by laser pulses in the environment of a nitrogen plasma generated from electron cyclotron resonance microwave discharge in pure nitrogen gas, while the growing film was simultaneously bombarded by the plasma stream. The deposited films were characterized by Rutherford backscattering spectroscopy (RBS), Fourier transform infrared (FTIR) spectroscopy, and Raman Spectroscopy. Films consisting purely of carbon and nitrogen with nitrogen content over at.50% were obtained on Si (100) substrates at low deposition temperatures (<80 degree(s)C). N atoms in the as-prepared films were found to be bound to C atoms through hybridized sp<SUP>2</SUP> and sp<SUP>3</SUP> configurations. A strong influence of substrate bias voltage on the composition and bonding configuration in the films as well as on the deposition rate was observed.
We report on the preparation of boron carbon nitride (BCN) thin films by pulsed laser ablation of a sintered B<SUB>4</SUB>C target and the compositional and structural characterization of the films. The film preparation was performed with assistance of nitrogen ion beam from a Kaufman source. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) were used for compositional analysis and structural characterization. The results showed that the prepared films contain several chemical bonds such as B-N and C-N. The BCN films were found to show good adhesion to the substrates and have a high transparency from visible to near-infrared region. WE also grew films in nitrogen background without ion beam assistance and in vacuum. The atomic ratio of boron, carbon and nitrogen and the chemical bonds are strongly dependent on the deposition conditions. The ion beam assistance, i.e. the reactive nitrogen environment and the bombardment of the growing films by the energetic species in the nitrogen ion beam, is beneficial to the incorporation of nitrogen.
We demonstrated the feasibility of the growth of GaN thin films from polycrystalline GaAs using reactive pulsed laser deposition. The films were grown on Si (100) substrates at temperatures lower than 80 degree(s)C. A bulk of polycrystalline GaAs was used as a target. Reactive nitrogen plasma was provided by electron cyclotron resonance (ECR) microwave discharge in pure nitrogen gas to assist the film growth. Composition analysis showed that the grown films are slightly N-rich, and arsenic can hardly be detected. A strong absorption peak corresponding to Ga-N stretching vibration in the hexagonal-type GaN crystals is clearly resolved from the IR absorption spectrum. The films exhibit transparency in the visible and near-IR regions. The band gap of the films was determined to be about 3.4eV. when excited by 325-nm light at 10.2 K, the grown films luminesce in the blue region.