Source Metalorganic Chemical Vapor Deposition Research Articles

Growth of CaS thin films by solid source metalorganic chemical vapor deposition

Using the solid source metalorganic chemical vapor deposition (MOCVD) technique, we were able to grow high quality CaS films on glass substrates with Ca(tmhd)2 and butanethiol as precursors at a reactor pressure of 76 Torr. The layers were colorless and at lower growth rates clear and specular reflective. At higher growth rates, the polycristalline nature of the layers became more obvious and the surface roughness increased. By means of X-ray photoelectron spectroscopy (XPS), no incorporation of carbon or oxygen could be detected. The temperature dependence of the growth rate showed a kinetically limited growth region up to about 500°C, followed by a temperature independent region indicating mass transport limitation. In both regions, the growth rate was dependent on the partial pressures of the Ca- and the S-precursor as well.

Epitaxial LiNbO3 thin films on sapphire substrates grown by solid source MOCVD

C-axis LiNbO3 epitaxial films have been grown on c-plane sapphire substrates by solid source metal-organic chemical vapor deposition (MOCVD) using the tetramethylheptanedionate sources, Li(thd) and Nb(thd)4. Stoichiometric LiNbO3 films were deposited from Li(thd)-rich source compositions. Rocking curve FWHM values as low as 0.044°were measured on films grown at 710 °C. Rocking curve peak widths became broader as films were grown at progressively lower substrate temperatures. Single prism coupling experiments revealed clearly visible optical waveguiding, with optical attenuation values as low as 2 dB/cm in the best films.

Single molecular precursor metal-organic chemical vapor deposition of MgAl2O4 thin films

MgAl2O4 films have been grown epitaxially on both Si(100) and MgO(100) by a novel single source metal-organic chemical vapor deposition (MOCVD) process. A single molecular source reagent [magnesium dialuminum isopropoxide, MgAl2(OC3H7)8] having the desired Mg: Al ratio was dissolved in a liquid solution and flash-vaporized into the reactor. Both thermal and plasma-enhanced MOCVD were used to grow epitaxial MgAl2O4 thin films. The Mg: Al ratio in the deposited films was the same as that of the starting compound (Mg: Al = 1:2) over a wide range of deposition conditions. The deposition temperature required for the formation of crystalline spinel was found to be significantly reduced and crystallinity was much improved on Si by using a remote plasma-enhanced MOCVD process. The epitaxial nature of the MgAl2O4 films was established by x-ray pole figure analysis.

Single source MOCVD of epitaxial oxide thin films

A novel and inexpensive single source metalorganic chemical vapor deposition (MOCVD) reactor has been developed at Hewlett Packard Laboratories, which permits the controlled and reproducible growth of device quality thin film heterostructures on a variety of substrates, using marginally volatile β-diketonate powdered solid sources. This reactor has been used to deposit state-of-the-art dielectrics, ferroelectrics and yttrium barium copper oxide (YBa 2 Cu 3 0 7 or YBCO) high temperature superconducting multi layers. The technique is readily applicable to many other oxide and non-oxide material systems. We describe herein the reactor and present the results of deposition experiments for single layers and heterostructures of YBCO on substrates up to 4 inches in diameter. To demonstrate the versatility of the reactor, we also present initial results for the deposition of other materials, including MgO, CeO 2 , Pr60 11 , barium cerate, hematite, and strontium barium niobate.

Solid source MOCVD for the epitaxial growth of thin oxide films

A novel solid source metalorganic chemical vapor deposition (MOCVD) process has been used to grow highly textured thin films of CeO2 and MgO, and highly oriented thin films of Sr1-xBaxNb206 (SBN). Both (100)-oriented and (lll)-oriented CeO2 films were reproducibly grown on (1102)-oriented Al203 (r-plane sapphire) substrates. Higher substrate temperatures and higher growth rates were found to favor the (111) orientation. The epitaxial (100) CeO2 films, 150 A thick, had very smooth surfaces, with an RMS surface roughness of 7 A, as measured by atomic force microscopy. MgO films with (100) orientation were readily grown on both r-plane sapphire and (100) SrTiO3 substrates at temperatures below 600°C. SBN films, 1.6 μm thick, were also grown on r-plane sapphire substrates at 700-800°C using a CeO2 buffer layer and all tetramethylheptanedionate (Sr, Ba, and Nb) metalorganic sources.

Single source metalorganic chemical vapor deposition of low microwave surface resistance YBa2Cu3O7

YBa2Cu3O7 films 2000–7500 Å thick were deposited onto [100] LaAlO3 substrates using a novel single source metalorganic chemical vapor deposition technique. We have so far observed critical currents as high as 4×106 A/cm2 at 77 K, transition temperatures (Tc at R=0) as high as 91 K, and the 10 GHz microwave surface resistance Rs as low as 40 μΩ at 4.2 K and 400 μΩ at 77 K.