Electronic Properties of OMVPE Grown films of YBa2Cu3O7-δ on 1” LaAlO3 Substrates

1992 ◽  
Vol 271 ◽  
Author(s):  
William S. Rees ◽  
Yusuf S. Hascicek ◽  
Louis R. Testardi
Keyword(s):  
Thin Films ◽  
Nitrous Oxide ◽  
Surface Morphology ◽  
Electronic Properties ◽  
Rotating Disk ◽  
Cold Wall ◽  
Rotating Disk Reactor ◽  
Substrate Temperatures ◽  
Source Materials

ABSTRACTFilms of YBa2CU3O7-δ have been grown on 1” LaAlO3 by OMVPE utilizing M(tmhd)n (M = Ba, Cu: n = 2; M = Y: n = 3; tmhd = 2,2,6,6-tetramethylheptane-3,5-dionato) as the source materials in a cold wall, vertical rotating disk reactor. The resultant films were characterized by SEM, XRD, Tc, Jc, and surface profilometry measurements. Relative to laser ablated thin films, the surface morphology was determined to be virtually featureless. In-situ depositions at substrate temperatures of <700°C, employing nitrous oxide as the oxidizing reagent, produced annular irregularities in the electronic properties of these films. The highest quality was observed near the film's center, with a marked decay evident toward the exterior 7 mm perimeter of the coated wafer.

In‐Situ Fabrication of YBa2Cu3O7‐x Superconducting Thin Films Directly on Silicon Substrates with Tc0 > 77K

1989 ◽  
Vol 169 ◽  
Author(s):  
C. B. Lee ◽  
R. K. Singh ◽  
S. Sharan ◽  
A. K. Singh ◽  
P. Tiwari ◽  
...  
Keyword(s):  
Thin Films ◽  
Laser Pulses ◽  
Superconducting Film ◽  
Laser Evaporation ◽  
Silicon Substrates ◽  
Superconducting Thin Films ◽  
Si Substrates ◽  
In Situ Fabrication ◽  
Substrate Temperatures

AbstractWe report in‐situ fabrication of c‐axis textured YBa2Cu3O7‐x superconducting thin films with Tco > 77K on unbuffered silicon substrates by the biased pulsed laser evaporation (PLE) technique in the temperature range of 550‐650°C. At substrate temperatures below 550°C, no c‐axis texturing of the superconducting film was observed. The YBa2Cu3O7‐x superconducting films were fabricated by ablating a bulk YBa2Cu3O7 target by a XeCl excimer laser (λ = 308 nm, τ = 45 × 10‐9 sec) in a chamber maintained at an oxygen pressure of 0.2 torr . The thickness of the films was varied from 0.3 to 0.5 nm depending on the number of laser pulses. Extensive diffusion was observed in thin films deposited at substrate temperatures above 550°C. However, microstructurally, with increase in the substrate temperature the films exhibited larger grain size and greater degree of c‐axis texturing (measured by the ratio of the (005) and (110) X‐ray diffraction peaks). This was found to give rise to better superconducting properties with Tco exceeding 77 K for YBa2Cu3O7‐x films deposited on Si substrates at 650°C.

scholarly journals Studies on the Optical Properties and Surface Morphology of Nickel Phthalocyanine Thin Films

2007 ◽  
Vol 4 (2) ◽  
pp. 255-264 ◽  
Author(s):  
Benny Joseph ◽  
C. S. Menon
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Band Gap ◽  
Electron Micrographs ◽  
Optical Band Gap ◽  
Scanning Electron Micrographs ◽  
Nickel Phthalocyanine ◽  
Glass Substrates ◽  
Substrate Temperatures ◽  
Scanning Electron

Thin films of Nickel Phthalocyanine (NiPc) are fabricated at a base pressure of 10-5m.bar using Hind-Hivac thermal evaporation plant. The films are deposited on to glass substrates at various temperatures 318, 363, 408 and 458K. The optical absorption spectra of these thin films are measured. Present studies reveal that the optical band gap energies of NiPc thin films are highly dependent on the substrate temperatures. The structure and surface morphology of the films deposited on glass substrates of temperatures 303, 363 and 458K are studied using X-ray diffractograms and Scanning Electron Micrographs (SEM), show that there is a change in the crystallinity and surface morphology due to change in the substrate temperatures. Full width at half maximum (FWHM) intensity of the diffraction peaks is also found reduced with increasing substrate temperatures. Scanning electron micrographs show that these crystals are fiber like at high substrate temperatures. The optical band gap increases with increase in substrate temperature and is then reduced with fiber-like grains at 408K. The band gap increases again at 458K with full of fiber like grains. Trap energy levels are also observed for these films.

Electrical Properties of Pulsed Laser Deposited ZnO Thin Films

2009 ◽  
Vol 67 ◽  
pp. 121-125
Author(s):  
Chattopadhyay Sourav ◽  
Kumar Nath Tapan
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Substrate Temperature ◽  
Hall Mobility ◽  
Pulsed Laser ◽  
Deposition Process ◽  
Zno Thin Films ◽  
Zno Films ◽  
Visible Absorption ◽  
Substrate Temperatures

Epitaxial Single-crystal ZnO thin films have been grown on c-plane (0001) sapphire by Pulsed Laser Deposition process at different substrate temperatures (300 – 800 °C) with 10-1 mbar oxygen pressure. The thicknesses of the films have been varied by varying number of pulses with a repetition rate of 10 pulse/sec. It is found that the sheet resistivity of ZnO thin films grown on c-plane sapphires are in the order of 10-2 Ω-cm and it increases with increasing substrate temperatures and film thickness. The carrier concentrations and Hall mobility are found to be in the order of 1017 cm-3 and ~195 cm2/V-s, respectively. The Hall mobility slightly decreases with increase of substrate temperature and thickness of the films. It is also found that the ZnO films are structurally uniform and well oriented with perfect wurtzite structure with c/a ratio 5.1. We have also deposited non-epitaxial ZnO films on (100) p-Silicon substrates at the same conditions. From HR FE-SEM micrographs, surface morphology of ZnO films grown at lower substrate temperature are found to be uniform compared to the films grown at higher temperatures showing non-uniformity and misoriented wurtzite structures. However, the surface morphology of ZnO flims grown epitaxially on (0001) sapphire are found to be more uniform and it does not change much with growth temperature. The resistivity of the films grown on p-Silicon at higher temperatures is in the order of 103 Ω-cm whereas films grown at lower substrate temperatures show comparatively lower resistivities (~ 102 Ω-cm). From the recorded UV-Visible absorption spectrum the band gap of the film has been estimated to be 3.38 eV.

SURFACE MORPHOLOGY AND PHOTOLUMINESCENCE CHARACTERISTICS OF Sm-DOPED YVO4 THIN FILMS

2007 ◽  
Vol 14 (05) ◽  
pp. 873-878 ◽  
Author(s):  
HYUN KYOUNG YANG ◽  
JONG WON CHUNG ◽  
BYUNG KEE MOON ◽  
BYUNG CHUN CHOI ◽  
JUNG HYUN JUNG ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Substrate Temperature ◽  
Photoluminescence Intensity ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Zircon Structure ◽  
Substrate Temperatures

Surface morphology and crystallinity of YVO 4: Sm 3+ thin films have an influence on the photoluminescence characteristics. The YVO 4: Sm 3+ films have been deposited on Al 2 O 3 (0001) substrates using pulsed laser deposition method. The films were grown at the various substrate temperatures changing from 500 to 700°C. The crystallinity and surface morphology of the films were investigated using X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. The results of XRD showed that YVO 4: Sm 3+ films had a zircon structure and AFM study revealed that the films consisted of homogeneous grains ranging from 100 to 400 nm depending on the deposition conditions. The photoluminescence spectra were measured at room temperature and the emitted radiation was dominated by the red emission peak at 620 nm radiated from the transition of 5 D 0-7 F 2. The crystallinity, surface morphology, and photoluminescence spectra of thin-film phosphors were highly dependent on the substrate temperature. The surface roughness and photoluminescence intensity of the films showed similar behavior as a function of substrate temperature.

Surface Morphology of in situ Superconducting Bi2Sr2CaCU2O8 Epitaxial Thin Films Grown on Various Substrates

1996 ◽  
pp. 1009-1012
Author(s):  
Shin-ichi Karimoto ◽  
Keiichi Tanabe ◽  
Shugo Kubo ◽  
Koji Tsuru ◽  
Minoru Suzuki
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Epitaxial Thin Films

Comparison of the surface morphology and microstructure of in situ and ex situ derived YBa2Cu3O7−x thin films

1993 ◽  
Vol 22 (8) ◽  
pp. 1113-1120 ◽  
Author(s):  
A. C. Westerheim ◽  
P. C. Mcintyre ◽  
S. N. Basu ◽  
D. Bhatt ◽  
L. S. Yu-Jahnes ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Ex Situ

In-Situ Dry Etching of InP Using Phosphorus Tri-Chloride and Re-Growth Inside a Chemical Beam Epitaxial Growth Chamber

1993 ◽  
Vol 300 ◽  
Author(s):  
K M. Kapre ◽  
W. T. Tsang ◽  
P. F. Sciortino
Keyword(s):  
Growth Rate ◽  
Surface Morphology ◽  
Epitaxial Growth ◽  
Substrate Surface ◽  
Etching Rate ◽  
Growth Chamber ◽  
Dramatic Improvement ◽  
First Time ◽  
Substrate Temperatures

ABSTRACTWe have extended the capability and versatility of a chemical beam epitaxial (CBE) system by demonstrating reactive chemical beam etching (RCBE) of InP using phosphorus tri chloride (PCl3)as the gaseous etching beam injected directly into the growth chamber. This permits instant switching from etching to growth (and vice versa) in the same run for the first time in CBE. We investigated RCBE of InP at various substrate temperatures between 400 °C and 580°C, under different PCl3 fluences, and etching conditions. Excellent surface morphology was obtained at high temperatures (> 530°C - 570°C) and under an etching rate of < 6 Å/sec. We also found that upon addition of trimethylindium flow equivalent to a growth rate of 1 Å/sec during RCBE a dramatic improvement in surface morphology was obtained even at a high net etching rate of 10 Å/sec. The surface morphology obtained under such conditions is indistinguishable from that of the original substrate surface. Using Si02 as a mask, in-situ etching of laser mesas followed immediately by regrowth of blocking layers with excellent wetting characteristics was obtained.

Growth of ZnO Thin Films by Using MOCVD with a High-Speed Rotating Disk Reactor

2008 ◽  
Vol 53 (9(5)) ◽  
pp. 2951-2954 ◽  
Author(s):  
Naoki Nishimoto ◽  
Obuliraj Senthilkumar ◽  
Takahiro Yamamae ◽  
Kasilingam Senthilkumar ◽  
Yasuhisa Fujita
Keyword(s):  
Thin Films ◽  
High Speed ◽  
Rotating Disk ◽  
Zno Thin Films ◽  
Rotating Disk Reactor

Si-N Bonding at The SiO2/Si Interfaces During Deposition of SiO2 by the Remote Pecvd Process

1991 ◽  
Vol 235 ◽  
Author(s):  
Y. Ma ◽  
T. Yasuda ◽  
S. Habermehl ◽  
G. Lucovsky
Keyword(s):  
Thin Films ◽  
Nitrous Oxide ◽  
Surface Passivation ◽  
Surface Roughening ◽  
Si Substrates ◽  
Processing Step ◽  
Atom Source

Thin films of SiO2 were deposited on Si substrates by remote PECVD following an in-situ cleaning/surface passivation with atomic-H. Si-N bonds were found in the immediate vicinity of the SiO2/Si interface when nitrous oxide, N2O, was used as O-atom source gas in the remote PECVD process. Si-N bonds, as well as Si-surface roughening produced by H-atom etching, contribute to the formation of high densities of midgap trapping states, Dit ∼1011 cm−2 eV−1, at the SiO2/Si interface. Eliminating the H-atom processing step, and exposing the Si surface to plasma-generated O-atoms prior to the SiO2 deposition: i) eliminated Si-N bonding at the Si/SiO2 interface; ii) reduced midgap Dit to ∼ 1–3×1010 cm−2eV−1 iii) eliminated surface roughening; and iv) improved process latitude and reproducibility.

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