RF reactive magnetron sputtering of copper nitride thin films and their field emission properties of nano-research

Title: RF reactive magnetron sputtering of copper nitride thin films and their field emission properties of nano-research Author: Wang Tao Degree-granting units: Lanzhou University Keywords: Copper nitride thin films;; RF reactive magnetron sputtering;; resistivity;; optical band gap;; field emission Abstract:
Cu_3N film material is one of the hot research in recent years, quite stable at room temperature and low thermal decomposition temperature, decomposition and decomposition of copper films produced before the copper nitride films in the infrared Neodymium Magnets and visible region of the very large difference in reflectivity , is expected to become light storage device of alternative materials, optical storage media, optical storage with the existing one-time-based inorganic tellurium phase change materials, it also has non-toxic, low-cost advantages. In addition, Cu_3N film can also be used to deposit metal films on Si buffer layer Cu wire, low magnetoresistive tunnel junction barrier layer, self-assembled materials, templates and so on. So far, Cu_3N physical and chemical properties of the film is still not very clear, most of the research is still in the preparation level, the different preparation process for Cu_3N great film performance. Reported in the international film about Cu_3N physical http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets and chemical properties are not consistent. The domestic film about Cu_3N rarely reported, so to carry out research work in this area is necessary.
Until now, many methods are used for the preparation of copper nitride films, including ion beam assisted deposition, RF magnetron sputtering and sputtering deposition. Currently the most frequently used with high efficiency and simplicity of the RF magnetron sputtering method. In this paper the use of radio frequency magnetron sputtering thin film prepared by nano Cu_3N, and the structure and properties were studied, the main contents include:
1. Studied the sputtering of hydrogen gas for thin film growth behavior. The proportion of different H_2/N_2 copper nitride films prepared have taken place in the priority growth of copper nitride. The proportion of samples in the 0% H_2/N_2 observed strong copper nitride (100) peaks at 2% -10% H_2/N_2 proportion of samples, although the film in the Cu / N ratio is relatively clear with H_2/N_2 percentage change, but even in 10% H_2/N_2 proportion of cases, the membrane structure also shows only small changes. This shows that the film along the selected (100) to the preferential growth orientation will not change with the increase of the proportion H_2/N_2 apparent change in the sputtering gas on the growth behavior of hydrogen is very small.
2. Of reaction gas H_2/N_2 the ratio of the film lattice constant, resistivity, optical band gap and other physical properties. XRD analysis shows that grain size in the nanometer scale, due to limitations of hydrogen nucleation, grain size ratio increases with the H_2/N_2; copper nitride thin films in nitrogen content increases with the proportion H_2/N_2 reduce the lattice constant decreases with; sample the optical band gap increased monotonically with H_2/N_2 ratio, that H doping within a certain range can be effectively adjusted Cu_3N film optical band gap; through the air environment Thermogravimetric analysis shows that with H_2/N_2 increase the proportion of reduced nitrogen content in the film, resulting in copper nitride thin films tend to thermal oxidation at low temperatures, the stability of the performance of a business trip, while in the decomposition process also showed greater sample weight; with H_2/N_2 increase the proportion, Cu_3N film resistivity decreases, which is due to increase in the proportion with hydrogen, the film did not occur to Cu_3N interstitial Cu atom body-centered space lattice of the phenomenon, excessive Cu atoms deposited on the amorphous form of grain boundaries as electron donor as a carrier providing thereby reducing the resistivity, Cu_3N film resistivity of controllability for applications in microelectronics to broaden the scope of the application of good prospects.
3. The use of diode structure field emission test device, the Cu / N ratio of 3.3:1 for the Cu_3N film field emission testing, the film field emission current is very unstable, and high turn-on field emission, emission current is small. H_2 gas by increasing the source content, film copper content increased to 80.8 at. %, The copper nitride thin films for field emission testing, found relatively stable field emission, emission current can reach the actual application requirements, but the turn-on field is still high. Analysis that the film increased copper content of copper nitride films help to improve field emission properties.
4. The use of Schottky emission, SCLC effect, SCLC + PF effect in turn on the theoretical formula for copper nitride film field emission data were fitted, the fitting correlation coefficients are high, that these effects of copper nitride thin films in field emission process have played a certain role, we observed the field emission Ⅰ - Ⅴ relationship is in fact a variety of surface conduction emission mechanism and the mechanism of FN result of the role. Degree Year: 2009