Thermal Metalorganic Chemical Vapor Research Articles

Tuning mechanical and corrosion performance of SiOC glass coatings prepared by thermal MOCVD

In this study, silicon oxycarbide (SiOC) glass coatings were successfully deposited by thermal metal organic chemical vapor deposition (MOCVD). The composition, chemical bonding and mechanical properties of the prepared SiOC glass coatings were studied using X-ray photoelectron spectroscopy (XPS) and nano indentation techniques. The surface morphologies of SiOC coatings were characterized by field emission scanning electron microscopy (FESEM) before and after etching with HF acid for prolong time. The results showed that the percentage of Si-C bonds in SiOC glass coatings increases with increasing the content of HMDS in liquid precursors mixture. Raman spectroscopy results revealed the presence of amorphous carbon (with high content of sp3 bonds) in the prepared SiOC coatings. Consequently, the hardness and modulus of SiOC glass coatings increased from 8.99 GPa and 82.6 GPa to 17.93 GPa and 195.6 GPa, respectively. Further, the prepared SiOC glass coatings exhibited excellent corrosion resistance against HF acid.

Qualification of a sublimation tool applied to the case of metalorganic chemical vapor deposition of In₂O₃ from In(tmhd)₃ as a solid precursor.

A solid delivery system consisting of a source canister, a gas management, and temperature controlled enclosure designed and manufactured by Air Liquide Electronics Systems was tested in the context of gas-phase delivery of the In(tmhd)3 solid precursor. The precursor stream was delivered to a thermal metalorganic chemical vapor deposition reactor to quantify deposition yield under various conditions of carrier gas flow and sublimation temperature. The data collected allowed the determination of characteristic parameters such as the maximum precursor flow rate (18.2 mg min(-1) in specified conditions) and the critical mass (defined as the minimum amount of precursor able to attain the maximum flow rate) found to be about 2.4 g, as well as an understanding of the influence of powder distribution inside the canister. Furthermore, this qualification enabled the determination of optimal delivery conditions which allowed for stable and reproducible precursor flow rates over long deposition times (equivalent to more than 47 h of experiment). The resulting In2O3 layers was compared with those elaborated via pulsed liquid injection obtained in the same chemical vapor deposition chamber and under the same deposition conditions.

Composition and microstructure of beryllium carbide films prepared by thermal MOCVD

Beryllium carbide films without columnar-crystal microstructures were prepared on the Si (100) substrate by thermal metal organic chemical vapor deposition using diethylberyllium as precursor. The influence of the substrate temperature on composition and microstructure of beryllium carbide films was systematically studied. Crystalline beryllium carbide is always the dominant phase according to XRD analysis. Meanwhile, a small amount of α-Be phase exists in films when the substrate temperature is below 400°C, and hydrocarbon or amorphous carbon exists when the temperature is beyond 400°C. Surfaces morphology shows transition from domes to cylinders, to humps, and to tetraquetrous crystalline needles with the increase of substrate temperature. No columnar grains are characterized throughout the thickness as revealed from the cross-section views. The average densities of these films are determined to be 2.04–2.17g/cm3. The findings indicate the substrate temperature has great influences on the composition and microstructure of the Be2C films grown by thermal MOCVD.

CHARACTERIZATION OF NANOSIZED AL2O3POWDER SYNTHESIZED BY THERMAL-ASSISTED MOCVD AND PLASMA-ASSISTED MOCVD

Nanosized Al2O3 powder is synthesized by thermal Metal Organic Chemical Vapor Deposition (MOCVD) combined with plasma. The effects of reaction temperature, pressure, Al(CH3)3 (TMA) concentration and reactant gases (CO2 and O2) on the characteristics of the synthesized Al2O3 powders are investigated. The experimental results demonstrate that very fine Al2O3 powders with mean particle size of about 2.5 nm can be obtained at 5.3kPa reactor pressure and 1000 o C by the thermal MOCVD. As the pressure is increased from 5.3kPa to 100 kPa, the mean diameter of Al2O3 powders also reaches to 10 nm. In other words, the increase in pressure has a negative effect on the synthesis of nanosized Al2O3. Meanwhile, it is also observed that the increment of temperature can promote the synthesis of fine Al2O3 powder.

10.2478/s11814-009-0293-5

The possibility of the formation of PbTiO3 from a multilayer structure of PbO and TiO2 layers on Pt-coated Si substrates prepared by rapid thermal metal organic chemical vapor deposition (RTMOCVD) followed by an appropriate annealing process was examined. The metal organic precursors of PbO and TiO2 were Pb(C2H5)4 and Ti(Oi-C3H7)4, respectively. The composition of the PbTiO3 thin film was adjusted by control of the thickness of each binary oxide layer of PbO and TiO2. The multilayer structure was converted into crystalline PbTiO3 by rapid thermal annealing under O2 ambient at temperature greater than 550 °C. As the annealing temperature was increased from 550 to 750 °C, the peaks related to perovskite PbTiO3 in the XRD patterns became stronger and sharper. From this study, it was confirmed that the crystalline PbTiO3 thin films could be prepared from the interdiffusion reaction of multilayer structure composed of primitive binary oxides through the appropriate post annealing process.

Formation of PbTiO3 films from multilayered structures of primitive oxides

The possibility of the formation of PbTiO3 from a multilayer structure of PbO and TiO2 layers on Pt-coated Si substrates prepared by rapid thermal metal organic chemical vapor deposition (RTMOCVD) followed by an appropriate annealing process was examined. The metal organic precursors of PbO and TiO2 were Pb(C2H5)4 and Ti(Oi-C3H7)4, respectively. The composition of the PbTiO3 thin film was adjusted by control of the thickness of each binary oxide layer of PbO and TiO2. The multilayer structure was converted into crystalline PbTiO3 by rapid thermal annealing under O2 ambient at temperature greater than 550 °C. As the annealing temperature was increased from 550 to 750 °C, the peaks related to perovskite PbTiO3 in the XRD patterns became stronger and sharper. From this study, it was confirmed that the crystalline PbTiO3 thin films could be prepared from the interdiffusion reaction of multilayer structure composed of primitive binary oxides through the appropriate post annealing process.

Capacitance-Voltage Analysis of ZrO2 Thin Films Deposited by Thermal MOCVD Technique

The capacitance-voltage (C-V) characteristics of thin films of ZrO2 deposited by thermal metal-organic chemical vapour deposition (MOCVD) have been analyzed. The films were grown at three different temperatures (500, 550 and 600 ºC) and 1 mbar pressure from a novel monomeric zirconium amide-guanidinate complex [Zr(NEtMe)2(guanidinate)2]. The true capacitance was determined from measurements made at different frequencies in order to account for the series and shunt parasitic resistances during C-V measurements. Films grown at 500 and 550 ºC showed no hysteresis while those grown at 600 ºC exhibited a very small hysteresis window ≈0.16 V for O2 flow of 100 sccm and ≈0.19 V for 50 sccm O2 flow. A very small voltage shift is also obtained for the device under 10 hr voltage stress. These preliminary in-depth electrical results suggest that quality ZrO2 can be grown from the novel [Zr(NEtMe)2(guanidinate)2] complex precursor paving the way for their use as future gate dielectrics.

Cubic SiC Nano-Thin Films and Nano-Wires: High Vacuum Metal-Organic Chemical Vapor Deposition, Surface Characterization, and Application Tests

Single-crystalline and epitaxial cubic silicon carbide (beta-SiC) nano-thin films have been deposited on Si(100) substrates at a sample temperature of approximately 900 degrees C using single source precursors by the thermal metal-organic chemical vapor deposition (MOCVD) method. Diethylmethylsilane and 1,3-disilabutane, which contain Si and C atoms in the same molecule, were used as precursors without any carrier or bubbler gas. Upon increasing the deposition temperature from 900 to 950 degrees C, beta-SiC nano-thin films with relatively small crystals and smoother surfaces were created on Si(100) substrates. Moreover, beta-SiC nano-wires with 40 approximately 100 nm in diameter have also been grown selectively on nickel catalyzed Si(100) substrates with dichloromethylvinylsilane by the MOCVD method. The deposition temperature in this case was as low as 800 degrees C under the pressure of 5.0 x 10(-2) Torr. It is worth noting that the initial growth rates of deposited beta-SiC nano-thin films and nano-wires strongly depend on the deposition temperature rather than the time. In order to test the possibility of applications of these materials for electronic components such as field emitter, MEMS, and high-power transistor, we fabricated the nanoelectronic devices using both beta-SiC nano-wires and nano-thin films. With these preliminary application tests, it is expected that SiC nanowires can be used as field emitter and nanoelectronic high-power transistor, and application of the SiC nano-thin films to MEMS is promising as well.

Electron field emission from semiconducting nanowires

In this paper we report on investigations of field emission (FE) properties of semiconducting (SiC, ZnO) one-dimensional (1D) nanostructures – nanowire/nanorod arrays, and fabrication of low-voltage field emission display (FED) devices based on these 1D nanomaterials. SiC nanowires were grown on Ni-coated Si substrates using a thermal metal-organic chemical vapor deposition (MOCVD) technique, and ZnO nanostructures were grown on gold-coated Si substrates by a thermal CVD method. Electron field emission properties of SiC and ZnO nanostructures were examined in plane geometry using a flat phosphor screen. The interrelation between the FE characteristics (emission thresholds, current density, surface uniformity, etc.) and microstructure and surface morphology of the produced 1D nanostructures was established. Diode-type FED devices (flat vacuum lamps) with SiC-nanowire-based cathodes were developed and fabricated. The FEDs are characterized by low threshold and operating electric fields – lower 2 V/μm and 5 V/μm, respectively, high current density and brightness, and stable performance of the nanowire-based cathodes.

Selective growth of iron oxide thin films using the combined method of metal-organic chemical vapor deposition and microcontact printing

The authors have carried out the selective deposition of magnetite iron oxide (Fe3O4) thin films with about 50nm thickness on Si(100) surfaces which were patterned by octadecyltrichlorosilane (OTS) using microcontact printing (μCP) method. The μCP method showed that hydrophobic patterns with microdimension were able to be formed on hydrophilic area such as silicon surface. Iron oxide thin films were deposited on the Si(100) substrates by thermal metal-organic chemical vapor deposition (MOCVD) method using single molecular organometallic precursor of iron pentacarbonly [Fe(CO)5] with high purity (99.999%) oxygen gas. The deposition was performed in the range of 250–350°C substrate temperature for 2–10min under 1×10−2Torr in a homemade MOCVD system. In order to check the selectivity of as-deposited thin films optical microscopy, scanning electron microscopy, and atomic force microscopy analyses were performed. To confirm the crystallinity of deposited thin films, x-ray diffraction patterns and micro-Raman were studied. Also energy dispersive x-ray and x-ray photoelectron spectrometry results showed the composition of the as-grown iron oxide thin films. By means of these results, the authors can suggest the selective deposition mechanisms and tendencies of iron oxide thin films onto the OTS patterned Si(100) surfaces.

Effect of Oxidizer on Chemical Vapor Deposited Hafnium Oxide-Based Nanostructures and the Engineering of their Interfaces with Si(100)

AbstractThin films of hafnium oxide were deposited on silicon substrates using tetrakis-diethylamino hafnium as precursor. Two different oxidizers: (a) ozone/oxygen mixture, and (b) dry oxygen were used for comparative study of the effect of different oxidizers on the deposited films. The deposition using dry oxygen was carried out in a cold-wall rapid thermal processing metalorganic chemical vapor deposition (MOCVD) reactor, whereas ozone/oxygen mixture was used in a cold-wall atomic layer deposition (ALD) reactor. Annealing studies were carried out at 600 and 800°C in high-purity argon at atmospheric pressure. X-ray photoelectron spectroscopy (XPS) analyses of as-deposited and annealed films were performed to study the HfO2/Si interface. The films deposited using these two different oxidizers appeared to be of comparable quality. Silicon oxide formation at the interface occurred after annealing at 600°C and it increased upon further annealing at 800 °C.

Structural and electrical characterization of strontium bismuth tantalate (SBT) thin films

Ferroelectric strontium bismuth tantalate (SBT) thin films were deposited by thermal metalorganic chemical vapour deposition (MOCVD) onto a complex layered Pt/IrO 2 /Ir/Ti(Al)N substrate. A study of ultra-violet (UV)-assisted rapid thermal processing (RTP) annealing strategies of the SBT thin films was performed. The influence of UV irradiation temperature and annealing atmosphere on the crystallinity of the deposited films was evaluated using both microstructural and electrical analysis techniques. A UV-RTP strategy in an oxygen atmosphere above 400 °C, followed by a furnace treatment at 700 °C, provided an optimum remnant polarization figure of merit.

A comparative study on SiC thin films grown on both uncatalyzed and Ni catalyzed Si(100) substrates by thermal MOCVD using single molecular precursors

We have deposited β-SiC thin films on Si(100) substrates using single source precursors by the thermal metal-organic chemical vapor deposition (MOCVD) method and analyzed their surface characterization. Diethylmethylsilane (C 2H 5SiH(CH 3)C 2H 5) was used as a single source precursor without any carrier or bubbler gas. With an increase of the deposition temperature from 700 to 900 °C, β-SiC thin films with relatively small crystals and smoother surfaces were deposited on Si(100) substrates. However, when the deposition temperature was raised to 1000 °C, the surface of the β-SiC thin film appears bursting on the deposited thin film. We could thus obtain the optimum β-SiC thin film using diethylmethylsilane at a deposition temperature as low as 900 °C. Moreover, we have succeeded in growing β-SiC nanowires with 40–100 nm diameter on nickel catalyzed Si(100) substrates using dichloromethylvinylsilane (CH 2CHSi(CH 3)Cl 2), at deposition temperatures as low as 800 °C and a pressure of 5.0 × 10 − 2 Torr. It is worth noticing that the initial growth rates of the deposited β-SiC thin films and nanowires strongly depend on the deposition temperature rather than on the time.

Hydrogenated amorphous and crystalline SiC thin films grown by RF-PECVD and thermal MOCVD; comparative study of structural and optical properties

Thin films of hydrogenated amorphous silicon carbide (a-SiC:H) and crystalline silicon carbide (c-SiC) with different compositions were deposited on Si(100) substrates by both RF plasma enhanced chemical vapor deposition and thermal metal organic chemical vapor deposition methods using a SiH4+CH4 gas mixture and a single molecular precursor of diethylmethylsilane, respectively. In this experiment, we mainly investigated the dependence of structural and optical properties of a-SiC:H and c-SiC thin films on the deposition parameters such as deposition temperature, pressure, RF power and annealing temperature. From this comparative study on structural and compositional differences of the a-SiC:H and c-SiC thin films, we realized that there are much different hydrogen contents and crystallinity in the films depending on the deposition temperature and annealing temperature. With increasing these parameters, moreover, the hydrogen contents and crystallinity are drastically changed to be less hydrogen and better crystalline films starting from amorphous, polycrystalline and single crystalline, sequentially. In addition, their optical properties are also strongly changed, for example, the refractive index and optical band gap are increased with increasing deposition temperature, pressure, RF power and annealing temperature. And the structural and optical properties of c-SiC thin film were analyzed with X-ray diffraction, scanning electron microscope, and infrared absorption techniques.

Fabrication Of Hard Coatings On NiTi Instruments

The present study was designed to compare the nature of modified surface layers obtained by two different procedures on endodontic files made of NiTi alloy: the procedures were arc evaporation physical vapor deposition and thermal metal organic chemical vapor deposition (MOCVD). Experimental samples were GT Rotary Instruments. The first method was based on the physical deposition of elemental titanium in the presence of nitrogen. The second technique is a typical MOCVD procedure which adopts Ti(Et2N)4 as a titanium and nitrogen precursor. Control samples were not exposed to any process. The chemical composition of the surface and in-depth layers of each sample were examined by X-ray photoelectron spectroscopy and X-ray diffraction measurements. The instruments showed surface chemical compositions that were different from those seen in the control group; samples treated with the first method show a surface Nitrogen/Titanium ratio of 1; MOCVD instruments show a surface Nitrogen/Titanium ratio of 1.7; control samples show a Nitrogen/Titanium ratio of 0.2. Both techniques can produce a high nitrogen concentration on the surface. However, data showed that the morphologies, the in-depth nitrogen distribution, and the chemical nature of the coatings obtained with the two procedures were different. The paper also reports the effects of the two deposition procedures on the nickel/titanium ratio of the surface.

Strongly oriented thin films of Co 3O 4 deposited on single-crystal MgO(1 0 0) by low-pressure, low-temperature MOCVD

We have grown epitaxial thin films of Co 3O 4 on single-crystal MgO at ∼400°C by low-pressure thermal metalorganic chemical vapor deposition using cobalt(II) acetylacetonate as the precursor. X-ray phi-scan analysis shows that cube-on-cube epitaxy of Co 3O 4 occurs on MgO(1 0 0) in the temperature range ∼400–550°C. Films grown on MgO(1 0 0) at 410°C show a rocking curve FWHM of only 0.44°, despite a rather large lattice mismatch of 4.1%. This is interpreted to be due to the excellent match between the oxygen sublattices of Co 3O 4(1 0 0) and MgO(1 0 0). The strong epitaxy which occurs, leads to a low activation energy ( E a) for growth on MgO. Scanning electron microscopy analysis shows faceted grains characteristic of the cubic symmetry of Co 3O 4, the faceting being stronger at higher growth temperatures.

Rapid thermal low-pressure metal organic chemical vapor deposition of Fe-doped InP layers

High quality Fe-doped InP layers have been grown by means of rapid thermal low-pressure metal organic chemical vapor deposition. Trimethylindium, tertiarybutylphosphine, and ferrocene were used as indium, phosphorus, and iron sources, respectively. The best growth conditions are: V–III ratio of 100 temperature of 650 °C, pressure of 4 Torr and growth rate of 2 μm/h. Featureless films were grown with a flat iron concentration of 2×1018 cm−3 as a function of depth, with an average specific resistivity of 108 Ω cm and a narrow x-ray half-maximum peak of 15 arcs.

Substrate dependent growth of highly conductive RuO2 films

We have prepared thin RuO 2 films by thermal evaporation metal organic chemical vapour deposition on r-plane Al 2 O 3 , MgO, LaAlO 3 and SrTiO 3 single crystal substrates. The films were grown at deposition temperature TD = 500 C, X-ray diffraction analysis show different type of preferred growth, depending on a substrate. Atomic force microscopy revealed typical surface morphology for each type of substrate. Room temperature resistivity of the films on various substrates varied between 30 and 40 μΩcm The best parameters were obtained for epitaxialy grown RuO 2 film on the r-plane cut Al 2 O 3 substrate with a room temperature resistivity about 30 μΩcm and residual resistivity ratio (resistivity ratio between room temperature and 4.2 K) close to30.

Low Temperature Direct Crystallization of SrBi2(Ta1-xNbx)2O9 Thin Films by Thermal Metalorganic Chemical Vapor Deposition and Their Properties

Directly crystallized SrBi2(Ta1-xNbx)2O9 (SBTN) films were deposited on (111) Pt/Ti/SiO2/Si substrates at 585–670°C by thermal metalorganic chemical vapor deposition (MOCVD). The crystalline SBTN film was directly deposited at 670°C irrespective of the deposition rate, but its leakage current markedly decreased when the deposition rate decreased from 5.0 to 2.1 nm/min. When the deposition rate was below 2.1 nm/min, an SBTN film with large ferroelectricity was deposited even at 585°C, and strong (103)-orientation was ascertained by an X-ray reciprocal space mapping method. This orientation is considered to locally epitaxially occur on a (111)-oriented Pt substrate. Twice the remanent polarization (2Pr) and twice the coercive field (2Ec) of the film deposited at 585°C were 12.2 µC/cm2 and 160 kV/cm, respectively. When the deposition temperature increased, the film became randomly oriented which was in response to the orientation change in the Pt substrate from single (111) to a mixed orientation of (111) and (100) orientations by heating before starting the film deposition. 2Pr and 2Ec of the film deposited at 670°C increased to 23.8 µC/cm2 and 190 kV/cm, respectively.

Effect of Deposition Temperature and Composition on the Microstructure and Electrical Property of SrBi2Ta2O9 Thin Films Prepared by Metalorganic Chemical Vapor Deposition

SrBi2Ta2O9 (SBT) thin films were prepared by conventional thermal metalorganic chemical vapor deposition (MOCVD) and subsequent heat treatment. The SBT film deposited at 500°C had a smoother surface and better step coverage than that deposited at 750°C. The degree of step coverage deposited at 500°C was 0.82. An almost single phase of SBT was obtained for the film with a Bi/Ta mole ratio of 1.0 by heat treatment at 750°C for 30 min in O2 atmosphere after MOCVD deposition at 500°C. 2Pr and EC at an applied electric field of 620 kV/cm were 12.2 µC/cm2 and 87 kV/cm, respectively, when the film was deposited at 500°C followed by heat treatment at 800°C for 30 min in O2 atmosphere, and its Bi/Ta ratio was 1.2.