Multifractal Spectra of INGaN/GaN Self-Assembled Quantum Dots Films

2010 ◽  
Vol 1 (3) ◽  
Author(s):  
Artde D. K. T. Lam
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
High Speed ◽  
Surface Characterization ◽  
Chemical Vapor ◽  
Surface Shape ◽  
Root Mean Square Roughness ◽  
Organic Chemical ◽  
Multifractal Spectra ◽  
Self Assembled

The surface shape and microstructure of semiconductor thin films, especially nanometer thin films, have important influence to construct physical characteristics, such as electricity, magnetic, and optics nature to the thin films. In this work, we use the multifractal spectra to study the surface morphology of InGaN/GaN self-assembled quantum dot films after the annealed process. Samples used in this study were grown on the (0001)-oriented sapphire (Al2O3) substrates in a vertical low-pressure metal-organic chemical vapor deposition reactor with a high-speed rotation disk. The fractal dimension and multifractal spectra can be used to describe the influence of different annealed conditions on surface characterization. Fractal analysis reveals that both the average surface roughness and root-mean-square roughness of nanostructure surfaces are decreased after the thermal annealing process. It can be seen that a smoother surface was obtained under an annealing temperature at 800°C, and it implies that the surface roughness of this case is minimum in all tests. The results of this paper also described a mathematical modeling method for the observation of the fractal and multifractal characteristics in a semiconductor nanostructure films.

Fractal Dimension and Multifractal Spectra of INGAN/GAN Self-Assembled Quantum Dots Films

2008 ◽  
Author(s):  
K. T. Lam
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Fractal Dimension ◽  
High Speed ◽  
Surface Characterization ◽  
Chemical Vapor ◽  
Surface Shape ◽  
Root Mean Square Roughness ◽  
Multifractal Spectra ◽  
Self Assembled

The surface shape and microstructure of semiconductor thin films, especially nanometer thin films, greatly influence such physical characteristics as the electricity, magnetic and optics nature to the thin films, etc. In this work, we use the fractal dimension and multifractal spectra to study the surface morphology of annealed InGaN/GaN self-assembled quantum dot (SAQD) films. Samples used in this study were grown on (0001)-oriented sapphire (Al2O3) substrates in a vertical low-pressure metalorganic chemical vapor deposition (MOCVD) reactor with a high-speed rotation disk. The fractal dimension and multifractal spectra can be used to describe the influence of different annealing conditions on surface characterization. Fractal analysis reveals that both the average surface roughness and root-mean-square roughness of nanostructure surfaces decreased after thermal annealing. It can be seen that a smoother surface was obtained after an annealing temperature of 800°C, and it implies that the surface roughness of this case is minimum in all tests. The results of this paper also include a mathematical model to describe the observation of fractal and multifractal characteristics in semiconductor nanostructure films.

EFFECTS OF THE ORGANIC SOLVENT IN CARRIER GAS ON THE PREPARED TiO2 THIN FILM BY METAL-ORGANIC CHEMICAL VAPOR DEPOSITION METHOD

2011 ◽  
Vol 25 (31) ◽  
pp. 4171-4174 ◽  
Author(s):  
Toshihide Horikawa ◽  
Hiroyuki Asano ◽  
Kazuhide Akiyama ◽  
Daisuke Nakahara ◽  
Masahiro Katoh
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Chemical Vapor Deposition ◽  
Organic Solvents ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Carrier Gas ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

Titanium dioxide ( TiO 2) thin films are prepared on glass substrates by metal-organic chemical vapor deposition (MOCVD) method using the different organic solvents, e.g. ethanol or cyclohexane, in nitrogen carrier gas with different their concentrations. We reported the effects of the each organic solvent in the carrier gas for MOCVD method on the morphology of the composed particles, the thickness, the surface roughness, and the transparency of the prepared TiO 2 thin films with changing the deposition temperature. The morphology of the particles which compose the thin films, and the surface roughness of the prepared TiO 2 thin films are observed and measured by atomic force microscope (AFM) and field emission scanning electron microscopy (FE-SEM). The film thickness is measured by fluorescent X-ray spectroscopy (XRF), and the transparency of the films is confirmed by UV-vis spectroscopy. The transparencies of the TiO 2 thin films differ depending on the MOCVD conditions, e.g. the organic solvents species, the concentration of the container in the carrier gas and the deposition temperatures. We have found that the species and the concentration of the organic solvents in the carrier gas are very important factor to prepare homogeneous TiO 2 thin films by MOCVD method; cyclohexane inhibits to aggregate of the TiO 2 nanoparticles on the glass substrate during the MOCVD process.

{10} edge dislocations in YSZ films grown on (100)MgO by PLD

1994 ◽  
Vol 52 ◽  
pp. 530-531
Author(s):  
Jason R. Heffelfinger ◽  
C. Barry Carter
Keyword(s):  
Thin Films ◽  
Semiconductor Lasers ◽  
Vapor Deposition ◽  
Substrate Surface ◽  
Laser System ◽  
Average Energy ◽  
Target Material ◽  
Chemical Vapor ◽  
Buffer Layers ◽  
Organic Chemical

Yttria-stabilized zirconia (YSZ) is currently used in a variety of applications including oxygen sensors, fuel cells, coatings for semiconductor lasers, and buffer layers for high-temperature superconducting films. Thin films of YSZ have been grown by metal-organic chemical vapor deposition, electrochemical vapor deposition, pulse-laser deposition (PLD), electron-beam evaporation, and sputtering. In this investigation, PLD was used to grow thin films of YSZ on (100) MgO substrates. This system proves to be an interesting example of relationships between interfaces and extrinsic dislocations in thin films of YSZ.In this experiment, a freshly cleaved (100) MgO substrate surface was prepared for deposition by cleaving a lmm-thick slice from a single-crystal MgO cube. The YSZ target material which contained 10mol% yttria was prepared from powders and sintered to 85% of theoretical density. The laser system used for the depositions was a Lambda Physik 210i excimer laser operating with KrF (λ=248nm, 1Hz repetition rate, average energy per pulse of 100mJ).

Observations on the Growth of YBa2Cu3O7 Thin Films at Very High Laser Fluences

1995 ◽  
Vol 388 ◽  
Author(s):  
Rand R. Biggers. ◽  
M. Grant Norton ◽  
I. Maartense ◽  
T.L. Peterson ◽  
E. K. Moser ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Organic Chemical ◽  
High Fluences ◽  
Laser Fluences ◽  
High Laser ◽  
High Laser Fluences ◽  
Very High

AbstractThe pulsed-laser deposition (PLD) technique utilizes one of the most energetic beams available to form thin films of the superconducting oxide YBa2Cu3O7 (YBCO). IN this study we examine the growth of YBCO at very high laser fluences (25 to 40 J/cm2); a more typical fluence for PLD would be nearer to 3 J/cm2. the use of high fluences leads to unique film microstructures which, in some cases, appear to be related to the correspondingly higher moveabilities of the adatoms. Films grown on vicinal substrates, using high laser fluences, exhibited well-defined elongated granular morphologies (with excellent transition temperature, Tc, and critical current density, Jc). Films grown on vicinal substrates using off-axis magnetron sputtering, plasma-enhanced metal organic chemical vapor deposition (PE-MOCVD), or PLD at more typical laser fluences showed some similar morphologies, but less well-defined. Under certain growth conditions, using high laser fluences with (001) oriented substrates, the YBCO films can exhibit a mixture of a- and c-axis growth where both crystallographic orientations nucleate on the substrate surface at the same time, and grow in concert. the ratio of a-axis oriented to c-axis oriented grains is strongly affected by the pulse repetition rate of the laser.

Properties of Tin Oxide Films Prepared by MOCVD

2004 ◽  
Vol 449-452 ◽  
pp. 997-1000 ◽  
Author(s):  
Gwang Pyo Choi ◽  
Yong Joo Park ◽  
Whyo Sup Noh ◽  
Jin Seong Park
Keyword(s):  
Thin Films ◽  
Oxygen Content ◽  
Tin Oxide ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition ◽  
Tin Oxide Films ◽  
N2 Annealing

Tin oxide thin films were deposited at 375 °C on α-alumina substrate by metal-organic chemical vapor deposition (MOCVD) process. A number of hillocks on the film were formed after air annealing at 500 °C for 30 min and few things in N2 annealing. The oxygen content and the binding energy after air annealing came to close the stoichiometric SnO2. The cauliflower hillocks of the film seem to be formed by the continuous migration of crystallites from a cauliflower grain on the substrate to release the stress due to the increase of oxygen content and volume.

Transparent conducting indium oxide thin films grown by low-temperature metal organic chemical vapor deposition

2007 ◽  
Vol 515 (5) ◽  
pp. 2921-2925 ◽  
Author(s):  
Chunyu Wang ◽  
Volker Cimalla ◽  
Genady Cherkashinin ◽  
Henry Romanus ◽  
Majdeddin Ali ◽  
...  
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Indium Oxide ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Transparent Conducting ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

Interdiffused InGaAsP Quantum Dots Lasers on GaAs by Metal Organic Chemical Vapor Deposition

2005 ◽  
Vol 891 ◽  
Author(s):  
Ronald A. Arif ◽  
Nam-Heon Kim ◽  
Luke J. Mawst ◽  
Nelson Tansu
Keyword(s):  
Quantum Dots ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Emission Wavelength ◽  
Organic Chemical ◽  
Phosphorus Species ◽  
Metal Organic ◽  
Self Assembled ◽  
Organic Chemical Vapor Deposition

ABSTRACTSelf-assembled InGaAs quantum dots (QD) grown by metal organic chemical vapor deposition (MOCVD) have a natural peak emission wavelength around 1150-1200-nm due to its specific composition, shapes, and sizes. In this work, a new method to engineer the emission wavelength capability of MOCVD-grown InGaAs QD on GaAs to ∼1000-nm by utilizing interdiffused InGaAsP QD has been demonstrated. Incorporation of phosphorus species from the GaAsP barriers into the MOCVD-grown self-assembled InGaAs QD is achieved by interdiffusion process. Reasonably low threshold characteristics of ∼ 200-280 A/cm2 have been obtained for interdiffused InGaAsP QD lasers emitting at 1040-nm, which corresponds to blue-shift of ∼ 85-90-nm in comparison to that of unannealed InGaAs QD laser.

Sign in / Sign up

Export Citation Format

Share Document