Carbon nitride may have many different uses as wear and corrosion resistant coatings, electrical insulators, and optical coatings. We report the results of using sputtering and negative carbon ion sources to prepare thin films of carbon nitride. In this work, we compare the tribological properties of the carbon nitride films that were prepared by two separate ion-beam assisted techniques. The first approach used an ONYX-2 magnetron to sputter deposit carbon in a nitrogen atmosphere with and without simultaneous bombardment of the growing film with low-energy (∼50–200 eV) nitrogen ions. The second method utilized a beam of negatively charged carbon ions of 1–5 mA/cm2 current density impinging the substrate at the same time with a positive nitrogen ion beam produced by an “Ion Tech” Kaufman source. We were able to produce microscopically smooth, continuous coatings that are harder than silicon. These films possess wear rates lower than 5×10−7 mm3/Nm and friction coefficients in the range of 0.16–0.6. These data compare favorably with the results obtained by other authors. Raman spectroscopy revealed that the magnetron sputtered films are more structurally disordered than those formed with the negative carbon ion gun. Fourier transform infrared spectroscopy showed the presence of C≡N stretching mode in both types of films.
We have demonstrated the basic operation of a vacuum diode based on the negative electron affinity polycrystalline AIN thin film emitters. The AIN films, both undoped and Ge doped, were deposited by ion beam assisted deposition (IBAD). The IBAD process utilizes thermal evaporation from either electron-beam or resistance heated sources with ion bombardment from Kaufman-type ion sources at energies from 50 to 1500 eV. Films were post-annealed by rapid thermal annealing and long-time tube furnace annealing in a N 2 atmosphere to test improvements in crystallinity. The electrical and transport properties of the films were tested by DC I-V measurements. The structure of the AIN films was investigated by TEM, SIMS, optical absorption, and RBS as a function of growth parameters and annealing. The field emission was tested for films with different Ge doping concentrations, film thickness, diode voltage, and post annealing conditions. Field emission was observed for the undoped AIN films with a thickness of approximately 10 nm.
A versatile control system, which uses standard commercial software and hardware has been developed and applied to control oxide (and carbide) MOCVD and CVD systems. The control system is implemented within a personal computer platform. The system operates in the real time Microsoft WindowsTM environment utilizing the full advantage of the sophisticated graphical user interfaces, dynamic data exchange, networking, and multitasking capabilities. We have used two different sets of commercial software to control and monitor system hardware. The first software set is INTOUCHTM, a Man-Machine interface software from WONDERWARETM in conjunction with Microsoft ExcelTM and I/O interface software. The second software set is LABVIEWTM, which is primarily a data acquisition control system from National Instruments, combined with Visual BasicTM. Both systems include a friendly interactive real-time windows-based user interface, an advanced process entry and recording spread sheet interface, alarm and security management systems, data display and recording, maintenance routines, and complete networking and remote operation capabilities. In addition, the configurations provide a flexible hardware interface that can directly interface to I/O cards in the PC's bus, as well as to most industrial Programmable Logic Controllers, various types of process controllers, I/O devices and other forms of hardware. Most importantly, the system can interface with any in-situ process monitor or higher level intelligent process control systems in order to optimize the process. Modules may be activated or deactivated as needed (even as part of the process). These systems have been used for home-built systems, as well as to retrofit a modified Spire SPI-MOCVDTM 500XT system. General process interaction and results will be discussed.
Theoretical works have indicated that carbon nitride, in a β-C4N4 phase, would have optical and mechanical properties comparable to or exceeding those of diamond. In this effort, the formation of carbon nitride thin films was investigated using a Plasma Assisted Ion Beam Deposition (PAIBD). In this technique, a C- ion beam combined with a N2 or NH3 RF plasma source is used to synthesize carbon nitride films. These films were investigated as a function of both C- ion beam energy and the power of the plasma source. The C- ion energy was found to be a key parameter in the formation of carbon nitride. The films were evaluated by a variety of diagnostic techniques including Raman, AES, XRD and FTIR. Analysis confirms high nitrogen concentration in the synthesized films and the major portion of carbon being single bonds in the sp3 bond configuration, which is a characteristic of the tetrahedral -C3N4 phase. Tribology tests confirmed that the friction coefficient and the wear rate are comparable to diamond. The results show that the higher C- ion beam energy (-150 eV) forms insulating films with the highest single bond percentages in the range studied. We believe beam energy control is critical to the types of bonds formed.
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