A H202-assisted sol-gel method for the preparation of precursors for formation of thin films of MgO is described. Sols were prepared from the addition of Mg(OCH3)2 to methanolic H2O2. Two such sols, with Mg to H202 ratios of 1:1 and 1:10, were used to prepare, respectively, random or (111) oriented MgO thin films on Si(100). The xerogel from a sol with a 1:10 Mg:H202 ratio contained nanocrystalline Mg02-nH20, whereas the xerogel from a comparable sol with a 1:1 Mg:H202 ratio contained nanocrystals of Mg02,nH20, and Mg-(OH)(OCH3). The latter compound was the hydrolysis product of methanolic Mg(OCH3)2 even when treated with up to 4 equiv of water. The thermal decomposition properties of this compound are reported. Using the published method of treating Mg(N03)2 with excess 30% H202, Mg02-nH20, with a Mg2+:022-ratio of 1:0.74, was prepared. Based on IR, TGA, and DTA results, it is proposed that the material also contained oxide, and possibly hydroxide ions for charge balance. These ions were present either in an amorphous phase, or possibly substituted for 022-in the Mg02 crystal structure.
Thin, protective films of nanocrystalline MgF 2 were formed by spin-coating a sol that contained nanocrystalline MgF 2 , which was formed by the action of HF on a sol prepared from methanolic H 2 O 2 and Mg(OCH 3 ) 2 . These thin films on Si(100) lost fluoride to form MgO when heated at 550 °C. When the films on two such substrates were placed together face to face and heated at 550 °C, rough, abrasion resistant MgF 2 films were obtained. To form composites, nanocrystalline MgF 2 sols were mixed with silicate sols prepared from the acid catalyzed hydrolysis and condensation of tetramethyl orthosilicate (TMOS). X-ray diffraction and TEM analysis of xerogels and films obtained from these biphasic sols indicated nanocrystals of MgF 2 dispersed in an amorphous matrix. On heating, fluoride loss and MgF 2 crystal growth were both greatly retarded in powders and thin films prepared from silicate-MgF 2 sols.
Mg-doped Ba0.96Ca0.04Ti0.84Zr0.16O3 (BCTZ) thin films have been proposed as a promising material for microelectronic device applications based on high dielectric materials. Perovskite polycrystalline Mg-doped BCTZ thin films were fabricated on a Pt/Ti/SiO2/Si substrate by metalorganic decomposition method. Dielectric properties were improved after a Pt/Mg-doped BCTZ thin film/Pt capacitor was post-annealed at 700 °C in O2 atmosphere for 30 min. A high dielectric constant of 460 at 1 MHz, a low dissipation factor less than 4.5%, and a low leakage current density of 4×10−7 A/cm2 at 3 V were obtained. Improved dielectric properties were discussed in conjunction with reduction of oxygen vacancies and electrons due to the post-annealing and Mg dopants.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.