Growth Rate Of ZnO Films Research Articles

Chemical reaction-transport model of diethylzinc hydrolysis in a vertical MOCVD reactor

ZnO thin film has many uses as a semiconductor material. It can be fabricated by chemical vapor deposition with diethylzinc (DEZn) and water vapor. The present study employs density functional theory to examine reaction complexes of DEZn with 1–2 molecules of water, which may occur in the gas phase according to previous studies. The kinetic and thermodynamic data provide a better understanding of the ZnO deposition process. A computational fluid dynamics analysis was carried out using the kinetic parameters to simulate the deposition rate of ZnO in a reaction chamber, showing the dependence of the film growth rate on temperature. The simulation data agreed with the experimental one within 8%, proving the feasibility of the current chemical reaction-transport model of diethylzinc hydrolysis. Furthermore, the fields of the flow, the temperature, the multi-species transport, and the chemical reaction were analyzed. These insights could reveal the reaction kinetics of ZnO thin film fabrication in the metal-organic chemical vapor deposition chamber. The results show that the pathway involving nucleation and growth of oligomers from trimers, and ultimately particle formation, is consistent with the decreased growth rate at increasing temperatures. The maximum growth rate of ZnO film was obtained at 573–773 K when ZnO is grown by DEZn and H2O in a horizontal chamber rotating at high speed. When the temperature is above 773 K, parasitic reactions lead to a rapid decline in the ZnO deposition rate. These insights could reveal the reaction kinetics of ZnO thin film fabrication; and help with the reactor design, optimization, and process parameter adjustment in the metal-organic chemical vapor deposition process.

Controlled Morphologies of Nanostructured ZnO Films by MOCVD Method

Metal-organic chemical vapor deposition (MOCVD) method has been applied to grow nanostructured ZnO films on Si (100) substrate at temperatures ranging from 200 to 550 °C. The as-prepared films were characterized by XRD, SEM, XPS analysis. The growth rate of ZnO films increases with increasing the deposition temperatures. The deposition temperatures have a drastic effect on the crystallinity and morphology of the nanostructured ZnO. Whisker shaped ZnO is formed at a temperature of 350 °C. The deposition time also affects the morphology of the particles. At 400 °C, sample with one hour deposition forms whisker shaped ZnO nanostructures whereas that of with two hours deposition forms flower-like nanostructures.

RETRACTED: Dependence of the structural and optical properties of ZnO thin films on the substrate temperature in atomic layer deposition and post-annealing

In this paper, the effects of substrate temperature during atomic layer deposition (ALD) and post-annealing temperature on microstructures and optical properties were investigated using X-ray diffraction (XRD), photoluminescence (PL) and scanning electron microscopy (SEM) techniques. The temperature window for ALD was found to be 130-180°C. The growth rate of ZnO film was increased as the substrate temperature was increased, and crystallinity was found to be strongly dependent on the substrate temperature among all the process parameters of ALD. Crystallinity of the ZnO thin film was observed to be improved with increase in the process time per ALD cycle or with post-annealing treatment. The grain size of the ZnO film tended to increase and the grain shape tended to change from a worm-like longish shape to a round one as the annealing temperature increased from 600 to 1000 °C.

Homoepitaxial growth of ZnO films via low-temperature liquid-phase epitaxy

Homoepitaxial ZnO films have been grown via liquid-phase epitaxy (LPE) on (0001) oriented ZnO substrates. X-ray rocking curve revealed the high quality of the ZnO films with a FWHM of 40 arc sec. Films of thickness about 20 μm were grown in the temperature range 700–720 °C. The growth rate of ZnO films was estimated to be 0.3 μm h − 1 . Atomic force microscope analysis showed that the surface roughness of ZnO films was very low, which further confirmed the high crystallinity of ZnO films.

Investigation on the Growth Mechanism of Zinc Oxide Film Prepared by Electrochemical Method

ABSTRACTZnO thin films were potentiostatically deposited on ITO electrode in 0.1 M Zn(NO3)2 and the film growth mechanism was investigated by using FTIR and electrochemical quartz crystal microbalance(EQCM). Intermediates formed in the initial stage were identified as soluble zinc hydroxides and a critical concentration of OH was required for the ZnO to be deposited. A rapid growth rate of ZnO film observed in the presence of O2 was attributed to the higher cathodic current which produces OH

New sputtering system for manufacturing ZnO thin-film SAW Devices

An improved rf sputtering system for manufacturing ZnO thin-film devices is described. The system consists of a hemispherical electrode geometry with a ZnO center cathode and provides c axis highly oriented ZnO films onto 60 sheets of glass substrate wafers of 25 mm square in one sputtering run. The growth rate of ZnO films is 0.3–0.7 μm/h. The film thickness variations in these wafers are within ±1%. The electrical resistivity of the films ρ?106–107 Ω cm, dielectric constant ε*?8.5, the electromechanical coupling in a longitudinal mode kt?0.23–0.24, in a Rayleigh mode keff?0.07–0.085 for the ZnO film thickness of 3% of the wavelength. The present system enables the manufacture of the ZnO thin-film SAW filter with a frequency accuracy, better than ±0.1%, and a temperature stability, better than −10 ppm/°C.