Fast Growth of Polycrystalline Film in SiCl4／H2 Plasma

We report the discovery, of fast growth of polycrystalline silicon films under low temperature of 200-300℃ from SiCl4/H2 mixture gases by plasma enhanced chemical vapour deposition technique. The deposition rate strongly depends not only on the rf power and the flow ratio of H2/SiCl4, but also on the substrate temperature, while the crystalline fraction is mainly affected by both the rf power and the flow ratio of H2/SiCl4. The high film-growth rate is due to the enhancement of the gas-phase reaction in SICI4/‘H2 plasma. By gleans of adjusting the matchingrelation between the flow ratio of H2/SiCl4 and rf power, and optimizing the substrate temperasure, we obtain the potycrystalline silicon films deposited at a higher deposition rate over 3.5A/s, with a crystalline fraction of 75% and an average crystallite size of 400-500nm in diameter.     

Growth of Nanocrystalline Silicon Films by Helicon Wave Plasma Chemical Vapour Deposition

Nanocrystalline silicon (nc-Si) thin films have been prepared by a helicon-wave plasma chemical vapour deposition technique on glass-Si substrates. The structural properties and the surface morphology are characterized by Raman spectroscopy, x-ray diffraction and atomic force microscopy. It is proven that the deposited films have the features of high crystalline fraction and large grain size compared with that in the normal plasma-enhanced chemical vapour deposition regime. The crystalline fraction of the deposited films varying from 0%to 72% can be obtained by adjusting the substrate temperature.     

Electron Field Emission of CNx Thin Films Prepared by Low Pressure Plasma Enhanced Chemical Vapour Deposition

CNx thin films were prepared using low pressure plasma enhanced chemical vapour deposition,and then bombarded by low-energy N2^ .The compositions before and after N2^ bombardment were compared using x-ray photoelectron spectroscopy.The electron field emission characteristics of CNx thin films before and after N2^ bombardment were studied under the pressure of 10^-6pa.For the samples,the turn-on emission field decreased from 2.5V/μm to 1.2V/μm while the stable current density increased from 0.5mA/cm^2 to a value larger than 1mA/cm^2 before and after the bombardment.Our results illustrate that the field emission characteristics were improved after the bombardment of N2^ .     

Al-Induced Crystallization Growth of Si Films by Inductively Coupled Plasma Chemical Vapour Deposition

Polycrystalline Si （poly-Si） films are in situ grown on Al-coated glass substrates by inductively coupled plasma chemical vapour deposition at a temperature as low as 350℃. Compared to the traditional annealing crystalliza- tion of amorphous Si/Al-layer structures, no layer exchange is observed and the resultant poly-Si film is much thicker than Al layer. By analysing the depth profiles of the elemental composition, no remains of A1 atoms are detected in Si layer within the limit （〈0.01 at.%） of the used evaluations. It is indicated that the poly-Si material obtained by Al-induced crystallization growth has more potential applications than that prepared by annealing the amorphous Si/Al-layer structures.     

Photoluminescence of ZnO and Mn-Doped ZnO Polycrystalline Films Prepared by Plasma Enhanced Chemical Vapour Deposition

ZnO and Mn-doped ZnO polycrystalline films are prepared by plasma enhanced chemical vapour deposition at low temperature （220℃）, and room-temperature photoluminescence of the films is systematically investigated. Analysis from x-ray diffraction reveals that a11 the prepared films exhibit the wurtzite structure of ZnO, and Mndoping does not induce the second phase in the films. X-ray photoelectron spectroscopy confirms the existence of Mn^2＋ ions in the films rather than metalic Mn or Mn^4＋ ions. The emission efficiency of the ZnO film is found to be dependent strongly on the post-treatment and to degrade with increasing temperature either in air or in nitrogen ambient. However, the enhancement of near band edge （NBE） emission is observed after hydrogenation in ammonia plasma, companied with more defect-related emission. Furthermore, the position of NBE shifts towards to high-energy legion with increasing Mn-doped concentration due to Mn incorporation into ZnO lattice.     

Growth of a-Plane GaN Films on r-Plane Sapphire Substrates by Metalorganic Chemical Vapour Deposition

Nonpolar a-plane CaN films were grown on r-plane sapphire substrates by metalorganic chemical vapour deposition (MOCVD) under various conditions. The surface morphologies of epitaxial films are studied by atomic force microscopy. The pit density and size both decrease with the increasing growth temperature, decreasing growth pressure or V/Ⅲ ratio, while the roughness of the surface increases. Formation mechanisms of the pits in the films are discussed.     

Comparative Study of Properties of ZnO／GaN／Al203 and ZnO／Al203 Films Grown by Low－Pressure Metal Organic Chemical Vapour Deposition

ZnO films were deposited by low-pressure metal organic chemical vapour deposition on epi-GaN/Al203 films and c-Al203 substrates. The structure and optical properties of the ZnO/GaN/Al203 and ZnO/Al203 films have been investigated to determine the differences between the two substrates. ZnO films on GaN/Al203 show very strong emission features associated with exciton transitions, just as ZnO films on Al2O3, while the crystalline structural qualities for ZnO films on GaN/Al2O3 are much better than those for ZnO films directly grown on Al203 substrates. Zn and O elements in the deposited ZnO/GaN/Al2O3 and ZnO/Al2O3 films are investigated and compared by x-ray photoelectron spectroscopy. According to the statistical results, the Zn/O ratio changes from Zn-rich for ZnO/Al2O3 films to O-rich for ZnO/GaN/Al2O3 films.     

Interfacial Properties of AlN／Si（111） Grown by Metal—Organic Chemical Vapour Deposition

We have studied the interfacial structures of AlN/Si(111) grown by metal-organic chemical vapour deposition.X-ray photoelectron spectroscopy and Anger electron spectroscopy were used to analyse the components and chemical structures of AlN/Si(111).The results indicated that a mix-crystal transition region,approximately 12nm,was present between the AlN film and the Si substrate and it was composed of AlN and Si3N4.After analysis we found that the existence of Si3N4 could not be avoided in the AlN/Si(111) interface because of strong diffusion at 1070℃.Even in AlN layer Si-N bonds,Si-Si bonds can be found.     

Atomic—Scale Kinetic Monte Carlo Simulation of {100}—Oriented Diamond Film Growth in C—H and C—H—CI Systems by Chemical Vapour Deposition

We simulate the {100}-oriented diamond film growth of chemical vapour deposition (CVD) under different models in C-H and C-H-Cl systems in an atomic scale by using the revised kinetic Monte Carlo method.The simulation results show that:(1) the CVD diamond film growth in the C-H system is suitable for high substrate temperature,and the film surface roughness is very coarse;(2) the CVD diamond film can grow in the C-H-Cl system either at high temperature or at low temperature,and the film quality is outstanding;(3) atomic Cl takes an active role for the growth of diamond film,especially at low temperatures.The concentration of atomic Cl should be controlled in a proper range.