Lassi Hiltunen

Nitrides of titanium, niobium, tantalum and molybdenum grown as thin films by the atomic layer epitaxy method☆

Abstract Cubic δ-TiN, cubic δ-NbN, cubic TaN, tetragonal Ta 3 N 5 , cubic γ-Mo 2 N and hexagonal δ-MoN were grown at 773 K from the corresponding chlorides and ammonia by the atomic layer epitaxy method. With the exception of tantalum nitrides the films show a preferred orientation of either (111) type (NbN and Mo 2 N) or (200) type (MoN and TiN). The nitrogen contents of the films were determined by the nuclear resonance broadening technique and compared with structure and other properties. The δ-NbN films with 55 at.% nitrogen had at room temperature a resistivity of 200 μΩ cm became superconducting below 10 K.

Zinc chalcogenide thin films grown by the atomic layer epitaxy technique using zinc acetate as source material

Abstract Anhydrous zinc acetate (Zn(CH 3 COO) 2 ) was found to be a suitable source material for growing thin films by the atomic layer epitaxy method. The growth of both ZnS and ZnO thin films with good reproducibility and uniform thickness from Zn(CH 3 COO) 2 and H 2 S or H 2 O respectively was demonstrated. ZnS thin films showed excellent crystallinity and a high orientation of the growth direction. The ZnO thin films were mainly amorphous and the growth rate was approximately one-fifth of that found for ZnS growth. Some experiments were also carried out to dope the ZnS films with manganese and terbium, resulting in yellow and green luminescence respectively.

Growth and characterization of aluminium oxide thin films deposited from various source materials by atomic layer epitaxy and chemical vapor deposition processes

Abstract Aluminium oxide thin films were prepared by the ALE process using AICI3 and A1(OR)3 (R = Et,Pr) as aluminium source and H2O, O2 or various aliphatic alcohols as oxygen source. The process was also operated in the CVD mode and the deposition rates and mechanisms were compared. The films were characterized by Auger and XRF spectrometries for trace element impurities while the chloride residues were quantitatively determined by chemical analysis. FTIR was used to study the residual OH groups. The measured electrical constants and environmental stability indicate that the films are suitable for practical applications as insulating and protective layers.

Alkaline earth sulfide thin films grown by atomic layer epitaxy

Abstract Alkaline earth sulfide (CaS, SrS, BaS) thin films have been grown by the atomic layer epitaxy method on glass substrates. Starting materials were the 2,2,6,6-tetramethyl-3,5-heptanedionato (thd) chelates of the alkaline earth metals and hydrogen sulfide. The growth rate was reasonable (0.3-0.4 A/cycle) and according to the X-ray diffraction patterns and Auger spectra the films were polycrystalline and chemically pure. All films were slightly oriented but each towards different directions: CaS along (220), SrS along (111) and BaS along (200).

Characterization of thin-film electroluminescent structures by SIMS and other analytical techniques

ZusammenfassungNeuentwickelte epitaktische Abscheideverfahren („Atomic Layer Epitaxy — ALE“) ermöglichen die Herstellung von elektroluminescierenden Dünnfilmstrukturen hoher Qualität, welche für verschiedene elektronische Displays eingesetzt werden können. Neben der lichtemittierenden Schicht — üblicherweise Mangan-dotiertes ZnS — enthalten derartige Strukturen einige andere Komponenten wie Al2O3- oder Indium-Zinn-Oxid-(ITO)-Schichten. Die Gesamtdicke aller Schichten eines Displays beträgt ca. 2 μm. Für die Bestimmung der Aktivatorkonzentration (Mn) sowie von Terbium und der Schichtdicke von ZnS wurde eine röntgenfluorescenzanalytische Routinemethode ausgearbeitet. Die Sekundär-Ionen-Massenspektrometrie (SIMS) ermöglicht die Charakterisierung der Schichtstrukturen und der Verunreinigungen in einzelnen Schichten. Dies gestattet insbesondere die Untersuchung der Verteilung und Diffusion des wichtigen Spurenelementes Natrium.SummaryThe recently developed Atomic Layer Epitaxy (ALE) method produces good quality electroluminescent thin-film structures which can be used in various display applications. Besides the light emitting layer which is usually ZnS: Mn2+, the structures contain several other components such as aluminium oxide and indium-tin oxide layers; the total thickness is around 2 μm. It was found that XRF provides a convenient way for the determination of activator concentrations and film thicknesses while SIMS can be used for the determination of depth profiles in a wide concentration range. A rapid and accurate method for the routine determination of Mn2+ and Tb3+ in ZnS by XRF is described and the use of SIMS for the study of sodium distribution and diffusion is discussed.

N-Quaternary Compounds. Part LVI. 3-Hydroxyquinoline-2(lH)-thiones and Their N-Vinylation.

Synthese de quinoleinediol-2,3 et conversion en dihydro-1,2 thiazolo [3,2-a] quinoleinioolate-4; scission de cette betaine en N- et S-vinyl quinoleines isomeres

Copper(II) complexes of 3-aminopropanols. Synthesis and structure of 3-aminopropanol(3-aminopropanolato)copper(II) iodide

Abstract Copper(II) trifluoromethanesulfonate was allowed to react with 3-aminopropanol (Hap) and lithium iodide in ethanol. The obtained blue crystals have the formula Cu(ap)(Hap)I, where ap is a 3-aminopropanolato anion. The space group of the complex is P21/c with Z = 4. The unit cell parameters are a = 894.4(2), b = 1368.9(5) c = 1030.9(2) pm and β = 113.31(2)°. The structure was solved on 1322 unique Mo Kα reflections to R = 0.045. The compound is made up of alkoxo-bridged [Cu(ap)(Hap)]2 dimers, which are polymerized through Hap molecules. Copper atoms have a distorted five-coordinated structure. Iodide ions are not coordinated to copper.

Crystal structure and thermal stability of potassium tetrathiocyanatoplatinate(II), K2Pt(SCN)4

Abstract The crystal structure of potassium tetrathiocyanatoplatinate(II), K 2 Pt(SCN) 4 , was refined from single crystal X-ray diffraction data to R value of 0.05. K 2 Pt(SCN) 4 crystallizes in the monoclinic space group P 2 1 / c ( Z = 2) with the following cell dimensions: a = 4.294(4), b = 12.869(8), c = 11.055(8) A, and β = 98.00(6)°. The crystal structure consists of layers of planar [Pt(SCN) 4 ] 2− complex anions parallel to the ac plane. Layers are linked by K + ions into a three dimensional network through NKS bonds. A very weak Pt-S-Pt interaction along the a axis results in [Pt(SCN) 6 ] 4− groups with strong tetragonal distortion. The nearly linear SCN − chains have a bent coordination to Pt through sulfur atoms. K + ions are coordinated to three sulfur and five nitrogen atoms in a strongly distorted bicapped trigonal prism arrangement. Both in air and in inert (argon) atmosphere K 2 Pt(SCN) 4 is stable up to 200 °C above which it decomposes through complex reactions involving several intermediate phases. The main phases formed are sulfates and oxides in air and sulfides in argon.

Crystal structure of ((C4H9)4N)3(Pr(NCS)6)

Abstract The crystal structure of tris(tetra-n-butylammonium)hexaisothiocyanatopraseodymate coordination compound ((C4H9)4N)3(Pr(NCS)6) has been determined from four-circle single-crystal X-ray diffractometer data obtained at room temperature. The crystals are triclinic, space group P 1 , with two formula units in the unit cell. The dimensions of the unit cell are as follows: a = 12.4186(50) A , b = 12.9268(31) A , c = 22.8477(60) A , α = 90.936(22)°, β = 92.423(35)° and γ = 96.752(38)°. A least-squares refinement based on F values gave a final R value of 0.077. The structure consists of praseodymium atoms coordinated to six nitrogens from thiocyanate groups. The coordination polyhedron approaches an ideal octahedron with only minor distortions. The thiocyanate groups are nearly linear. The coordination of n-butyl groups to the nitrogen is tetrahedral and the butyl groups were found to be partly disordered.

Crystal structure, thermal behavior, and infrared absorption spectrum of cesium hydrogen selenite-selenious acid (12) CsHSeO3 · 2H2SeO3

Abstract The present work describes the crystal structure, thermal behavior, and infrared absorption spectrum of cesium hydrogen selenite-selenious acid (12), CsHSeO 3 · 2H 2 SeO 3 . This compound crystallizes in the monoclinic crystal system withP2 1 c-C 5 2b (Z = 4) as the space group. The unit cell dimensions are as follows:a = 8.9897(20), b = 8.5078(21), c = 12.6476(31)A˚, and β = 95.141(19)°. The crystal structure consists of discrete H 2 SeO 3 molecules which are weakly hydrogen bonded to form layers which are further connected by (HSeO 3 ) − ions with much stronger hydrogen bonds. The hydrogen atoms show no disorder within the hydrogen bonds. The Cs + ions are coordinated to oxygens from both selenious acid molecules and hydrogen selenite ions. The thermal decomposition of CsHSeO 3 · 2H 2 SeO 3 in air starts with incongruent melting due to rupture of hydrogen bonds at 310 K and is followed later by the formation of cesium diselenite phase. At higher temperatures (700 K) this compound decomposes with oxidation of selenium to yield cesium selenate. Both deformation and stretching vibrations of SeOH groups from both (HSeO 3 ) − ions and H 2 SeO 3 molecules can be found in the IR absorption spectrum of CsHSeO 3 · 2H 2 SeO 3 . This confirms the ordered position of hydrogen atoms in hydrogen bonds. The OH vibrations corresponding to hydrogen bonded species can be found also.