Structural and chemical stability of thin films of Pt–Ga intermetallic compounds of GaAs(001)

1990 ◽  
Vol 5 (10) ◽  
pp. 2139-2151 ◽  
Author(s):  
Young K. Kim ◽  
Delroy A. Baugh ◽  
David K. Shuh ◽  
R. Stanley Williams ◽  
Larry P. Sadwick ◽  
...  

Nearly single-phase thin films of three different Pt–Ga intermetallic compounds have been grown on GaAs(001) by co-deposition of Pt and Ga. The resultant films have been annealed at various temperatures and then characterized using x-ray two-theta diffractometry (XRD), Auger electron spectroscopy (AES), and x-ray photoemission spectroscopy (XPS). The XRD results showed that PtGa2 and PtGa thin films are chemically stable on GaAs under one atmosphere of N2 up to 800 °C and 600 °C, respectively, but thin films of Pt2Ga react with GaAs at temperatures as low as 200 °C to form phases with higher Ga concentration PtAs2. The XRD patterns also revealed that the crystallite orientation and texture of the films were dependent on annealing temperature. Segregation of Ga to the surfaces of the films upon annealing was also observed by both AES and XPS. The results demonstrated that the as-deposited films of PtGa2 and PtGa were kinetically stabilized with respect to possible chemical reactions with the GaAs substrates that evolve gaseous As species during open system annealing.

2000 ◽  
Vol 14 (22n23) ◽  
pp. 801-808 ◽  
Author(s):  
M. RAJENDRAN ◽  
M. GHANASHYAM KRISHNA ◽  
A. K. BHATTACHARYA

A novel all-inorganic aqueous sol–gel process has been developed to fabricate LaFeO3 thin films by dip-coating. Stable, positively charged colloidal sol particles of hydrous lanthanum ferrite with an average particle size (Z av ) of 7 nm were prepared and coated onto quartz plates under controlled conditions. The sols have been characterized using photon correlation spectroscopy (PCS) for Z av and size distribution. The redispersible gel was characterized by thermogravimetric and differential thermal analysis (TG-DTA) and also by isothermal heating followed by X-ray diffraction to identify the reaction sequence to form LaFeO 3. The sol–gel films as deposited were X-ray amorphous on heating up to 500°C, partially crystalline at 600°C, fully crystalline and single phase at 650°C and above. These films were continuous, polycrystalline, single phase, had uniform thickness in the range between 180 to 1000 nm, depending on deposition conditions, and showed about 80% optical transmittance. The optical band gap varied from 2.7 to 3.3 eV as a function of the annealing temperature. The refractive index increased with increase in annealing temperature from 1.55 at 500°C to 1.86 at 800°C.


2017 ◽  
Vol 890 ◽  
pp. 295-298 ◽  
Author(s):  
Ngamnit Wongcharoen ◽  
Thitinai Gaewdang

SnS thin films were deposited by thermal evaporation in vacuum on glass slide substrate. The as-deposited films were thermally annealed in a controlled N2 atmosphere with annealing temperature in the range 100-500°C for 30 min. XRD, AFM, UV-VIS transmittance, FTIR and Hall effect measurements were used for characterization the as-deposited and annealed films. Based on the XRD patterns, the as-deposited and annealed films were indentified as the orthrombic structure. The band gap was found to increase from 1.15 to 1.42 eV when the annealing temperature increased from 100 to 500°C. The lowest resistivity and highest carrier concentration values were observed to be 12.95 Ω.cm and 1.98×1016 cm-3 on the films annealed at 100 and 200°C, respectively.


2011 ◽  
Vol 25 (22) ◽  
pp. 2983-2990 ◽  
Author(s):  
YINQIAO PENG ◽  
JICHENG ZHOU ◽  
XUQIANG ZHENG ◽  
BAOXING ZHAO ◽  
XIAOCHAO TAN

Silicon oxycarbide ( SiCO ) thin films were prepared by the RF reactive sputtering technique on n-type silicon substrates with the target of sintered silicon carbide ( SiC ), and high purity oxygen was used as the reactant gas. The as-deposited films were annealed at temperatures of 600°C, 800°C, and 1000°C under nitrogen ambient, respectively. The films were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and photoluminescence (PL) spectrophotometer. The results show that annealing temperature plays an important role in the structure and photoluminescence of the films. The temperature 600°C is the most favorable annealing temperature for SiO 2 crystallization and the formation of 6H- SiC crystal phase in the SiCO films. The intense PL peaks located at 375 nm and 470 nm are observed at room temperature. The origin of the PL was discussed.


2013 ◽  
Vol 750-752 ◽  
pp. 1024-1028 ◽  
Author(s):  
Wei Rao ◽  
Yun Bo Wang ◽  
Ye An Wang ◽  
Jun Xiong Gao ◽  
Wen Li Zhou ◽  
...  

The thin films of CoFe2O4spinel ferrite were prepared on the substrates of monocrystalline silicon(100) at low temperature by means of a developed citrate processing.Structural properties and surface morphology of deposited films were examined using an X-ray diffractometer (XRD) and a field emission scanning electron microscope (FESEM). XRD patterns of all deposited films consisted of a single phase of cobalt ferrite and they did not have any preferred orientation. FESEM micrographs of CoFe2O4films showed that the film calcined at 400°C had a surface morphology different from the ones at 700°C and 800°C. The surface morphology of the samples was very different with various alcined temperatures. Magnetic properties measured at room temperature showed that the films did not have any magnetically preferred orientation. The maximum values of the coercivities measured at perpendicular and in-plane directions were 3.873 and 2.70 kOe, respectively.


1995 ◽  
Vol 401 ◽  
Author(s):  
L.A. Knauss ◽  
J.M. Pond ◽  
J.S. Horwitz ◽  
C.H. Mueller ◽  
R.E. Treece ◽  
...  

AbstractThe effect of a post deposition anneal on the structure and dielectric properties of epitaxial Sr1−x, BaxTiO3 (SBT) thin films with x = 0.35, 0.50 and 0.60 has been measured. The films were grown by pulsed laser deposition on LaAlO3(001) substrates at 750°C in 350 mTorr of oxygen. The asdeposited films were single phase, (001) oriented with 0)-scan widths for the (002) reflection between 0.160 and 0.50'. The dielectric properties of the as-deposited films exhibit a broad temperature dependence and a peak which is as much as 50 K below the peak in bulk SBT. Also, the lattice parameter, as measured by x-ray diffraction, of the as-deposited films was larger than the bulk indicating strain in the films. The as-deposited films were annealed for 8 hours at 900°C in oxygen. The dielectric properties of the annealed films were closer to that of bulk SBT and the lattice parameter was closer to the bulk lattice parameter indicating a reduction of strain. Annealing of as-deposited films also resulted in an increased dielectric tuning without increased dielectric loss.


2019 ◽  
Vol 15 (33) ◽  
pp. 40-48
Author(s):  
Atyaf H. Kadhum

The effect of heat treatment on the optical properties of the bulk heterojunction blend nickel (II) phthalocyanine tetrasulfonic acid tetrasodium salt and Tris (8-hydroxyquinolinato) Aluminum (NiPcTs/Alq3) thin films which prepared by spin coating was described in this study. The films coated on a glass substrate with speed of 1500 rpm for 1.5 min and treated with different annealing temperature (373, 423 and 473) K. The samples characterized using UV-Vis, X ray diffraction and Fourier transform Infrared (FTIR) spectra, XRD patterns indicated the presence of amorphous and polycrystalline blend (NiPcTs/Alq3). The results of UV visible shows that the band gap increase with increasing the annealing temperature up to 373 K and decreases with increase the annealing temperature to (423, 473)K respectively.


Author(s):  
Л.Н. Маскаева ◽  
В.М. Юрк ◽  
В.Ф. Марков ◽  
М.В. Кузнецов ◽  
В.И. Bоронин ◽  
...  

PbSe thin films chemically deposited using ascorbic acid as an antioxidant for selenourea were examined by X -ray diffraction (XRD), scanning electron microscopy (SEM) with X -ray microanalysis (EDX) and X -ray photoelectron spectroscopy (XPS). Influence of annealing temperature on chemical and phase composition, lattice parameters, surface morphology and photoelectric properties were studied. Determined that PbSe thin films contain dopant phase PbSeO3, PbSeO4, PbI2 after annealing at 633−683K. The direct and indirect optical band gaps Eg layers were observed. It has been shown that the deposited films are comparable with known commercial samples by their threshold photoelectric characteristics and can be used to create highly sensitive IR detectors.


1990 ◽  
Author(s):  
Young K. Kim ◽  
David K. Shuh ◽  
R. S. Williams ◽  
Larry P. Sadwick ◽  
Kang L. Wang

2012 ◽  
Vol 501 ◽  
pp. 236-241 ◽  
Author(s):  
Ftema W. Aldbea ◽  
Noor Bahyah Ibrahim ◽  
Mustafa Hj. Abdullah ◽  
Ramadan E. Shaiboub

Thin films nanoparticles TbxY3-xFe5O12 (x=0.0, 1.0, 2.0) were prepared by the sol-gel process followed by annealing process at various annealing temperatures of 700° C, 800° C and 900° C in air for 2 h. The results obtained from X-ray diffractometer (XRD) show that the films annealed below 900°C exhibit peaks of garnet mixed with small amounts of YFeO3 and Fe2O3. Pure garnet phase has been detected in the films annealed at 900°C. Before annealing the films show amorphous structures. The particles sizes measurement using the field emission scanning electron microscope (FE-SEM) showed that the particles sizes increased as the annealing temperature increased. The magnetic properties were measured at room temperature using the vibrating sample magnetometer (VSM). The saturation magnetization (Ms) of the films also increased with the annealing temperature. However, different behavior of coercivity (Hc) has been observed as the annealing temperature was increased.


2018 ◽  
Vol 17 (03) ◽  
pp. 1760039
Author(s):  
K. M. Dhanisha ◽  
M. Manoj Christopher ◽  
M. Abinaya ◽  
P. Deepak Raj ◽  
M. Sridharan

The present work deals with NiO/Si3N4 layers formed by depositing nickel oxide (NiO) thin films over silicon nitrate (Si3N[Formula: see text] thin films. NiO films were coated on Si3N4-coated Si substrate using magnetron sputtering method by changing duration of coating time and were analyzed using X-ray diffractometer, field emission-scanning electron microscopy, UV–Vis spectrophotometer and four-point probe method to study the influence of thickness on physical properties. Crystallinity of the deposited films increases with increase in thickness. All films exhibited spherical-like structure, and with increase in deposition time, grains are coalesced to form smooth surface morphology. The optical bandgap of NiO films was found to decrease from 3.31[Formula: see text]eV to 3.22[Formula: see text]eV with upsurge in the thickness. The film deposited for 30[Formula: see text]min exhibits temperature coefficient resistance of [Formula: see text]1.77%/[Formula: see text]C as measured at 80[Formula: see text]C.


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