Growth and characterization of GaInNxAs1-x thin films with band-gap energies in the red-blue portion of the visible spectrum (original) (raw)
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Control of stress and crystalline quality in GaInN films used for green emitters
Journal of Crystal Growth, 2008
We succeeded in growing almost completely relaxed, high-quality, thick GaInN films on an m-plane GaN template with grooves along the /0 0 0 1S direction, using lateral-growth technology. Reciprocal space mapping of asymmetrical X-ray diffraction confirmed almost complete relaxation. By transmission electroscopic characterization, the growth of GaInN film with a threading dislocation density of approximately 1 Â10 8 cm À2 was confirmed.
Influence of active nitrogen species on surface and optical properties of epitaxial GaN films
Journal of Alloys and Compounds, 2016
Influence of active nitrogen species on surface and optical properties of homoepitaxial GaN films grown on GaN epilayers has been investigated. The epitaxial GaN films were grown at varying plasma powers (350e500 W) under identical growth conditions. High resolution X-Ray diffraction, Field Emission Scanning Electron Microscopy, Atomic Force Microscopy and Photoluminescence measurements were employed to characterize the structural, morphological and optical properties of the grown GaN films. High plasma power (500 W) lead to an increment in active nitrogen radicals and yielded high crystalline quality with reduced dislocations compared to low plasma power (350, 400 W) which divulge the presence of metallic gallium on the surface and low roughness. The valence band maximum position, electron affinity and ionization energy of the films increased with increment in plasma power. PL measurements revealed narrow and intense band to band edge emission with negligible defect related yellow band peak for the sample grown at 500 W. The analysis conveyed that higher amount of active nitrogen species encouraged good optical properties with insignificant defect states which can be employed for the fabrication of high performance optoelectronic & photovoltaic devices.
Physica Status Solidi B-basic Solid State Physics, 2002
ABSTRACT We present results on the growth of GaInNAs semiconductor thin films which present evidence of a nanocrystalline GaAs background. The films were grown using the radio frequency sputtering deposition technique in a working gas atmosphere mixture of argon and nitrogen. X-ray diffractograms show evidence of the presence of a phase of GaInNAs material with high N concentration, and of a phase of GaAs material with crystallite sizes in the order of nanometers. From the absorption spectra measured by the photoacoustic technique we show that we have obtained the GaInNAs alloys with variable band gap energies, but also that this alloy is embedded in a background of nanocrystalline GaAs material. We discuss the nature of this formation, the quantum confinement effects evidenced from the absorption spectra, and the grain sizes obtained from the use of a spherical quantum dot model.
The microstructure and optical properties of Al x Ga 1-x N/GaN heterostructures thin films grown on Si(111) substrate by Plasma Assisted-Metalorganic Chemical Vapor Deposition (PA-MOCVD) with various of TMAl flow rate from 0.05 to 0.13 sccm have been investigated. The x values of Al x Ga 1-x N thin films were determined by NIR-UV visible optical reflectance spectroscope. The crystalline plane orientation and surface morphology of films were determined by X-ray diffractometer (XRD) and scanning electron microscope (SEM), respectively. The films with x = 0.29 and x = 0.36 have single crystalline orientation of (1010) plane while the film with x = 0.12 has two crystalline orientation of and planes. The surface morphology of films depend on the x value of film, which is the film with higher of x value showed the smaller grain size and the smoother surface. The patterns of optical reflectance show that the ordered of oscillation depend on smoothness of film surface, on the other hand the number of oscillation related to the thickness of films. These results were confirmed by surface morphology and cross section of films with means of SEM images. Band to band absorption mechanism (≈band gap energy, Eg) were indicated by the end of the peak oscillation position obtained that the Eg of GaN thin films was 3.34 eV and the Eg of Al x Ga 1-x N thin films were ranged from 3.34 to 6.20 eV, depend on the x values of films.
Growth of GaP1-xNx thin films by rf sputtering
Physica Status Solidi B-basic Solid State Physics, 2005
We have deposited GaP1–xNx thin films on glass substrates by rf sputtering employing a nitrogen–argon atmosphere. The films properties were studied as a function of the growth temperature in the range of 420–520 °C. The films characterization was carried out by absorbance, X-ray diffraction and Raman spectroscopy. The GaP1–xNx films have a cubic polycrystalline structure with a preferential orientation along the [111] direction; the structural properties of the films are improved by increasing the growth temperature up to 500 °C. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN Films under Different Growth Mechanisms Studied by Synchrotron X-ray Absorption Spectroscopy
Proceedings of the 2nd Annual International Conference on Advanced Material Engineering (AME 2016), 2016
Synchrotron radiation X-ray absorptionmeasurements wereperformed to study the structure of Si-doped n-type GaN layers grown on sapphire by metalorganic chemical vapor deposition (MOCVD) and undoped GaN epitaxial layers grown on Si by molecular beam epitaxy (MBE).It was found that the anisotropic characteristic of p-orbital from GaN/sapphire grown by MOCVD is somehow larger than GaN/Si grown by MBE.In addition, values of the lattice constant of different GaN films were deduced from the interatomic distances in the second coordination shell around Ga byextended X-ray absorption fine structure (EXAFS) analysis and the residual strain of the films was then deduced. The calculation results shows that the strain type is different in the two sets of samples which is due to the different substrate and AlN buffer layer.
The properties and deposition process of GaN films grown by reactive sputtering at low temperatures
Journal of Applied Physics, 2006
Polycrystalline gallium nitride films, 100 nm to 1 m thick, were deposited under a range of conditions. Substrate electrode temperatures during sputtering were varied from room temperature to 450°C, the pressure from 0.15 to 6.0 Pa, the nitrogen fraction of the deposition atmosphere from 10% to 100% and the target bias from −400 to − 1800 V. The deposition rates as functions of these conditions are in the range 0.5-25 nm/ min. The growth rate is considered to be controlled respectively by the thermally activated desorption from the substrate, changes in the mean free path and concentration of gas particles, differences between the sputter yields of Ga and GaN in Ar and N 2 , and changes in the ion current and sputter yields. The films are generally columnar, with the grain size increasing with film thickness. The most crystalline films were grown at mid range temperatures, low N 2 concentrations, and low target biases, and the most disordered were grown at low pressures. The latter two cases suggest that decreasing the energy of particles incident on the film during deposition results in a more ordered film. The biaxial stress is compressive and shows an increasing trend with the target bias and N 2 concentration, reaching 4.7 GPa at 75% N 2. Oxygen contamination of 3-30 at. % has a major effect on the optical properties of the films, increasing the band gap values from 3.02 to Ͼ 4.0 eV and the Urbach tail energies from around 150 to 840 meV and decreasing the refractive index from 2.46 to 2.03. At a 40% N 2 deposition fraction, the N:Ga ratio is more or less constant at 1:1. Since the absolute oxygen incorporation rate changes very little, it is the relative film deposition rate which determines the final oxygen concentration. Excess Ga at low N 2 concentrations causes a decrease in the band gap and an increase in the Urbach tail energy.
Materials Research, 2022
This work reports the properties of GaN films grown onto c-Si (100) at relatively low substrate temperature (400°C) by reactive magnetron sputtering. The study depicts the effect of working pressure and RF power on the GaN film structural, vibrational and optical properties characterized by X-ray diffraction, atomic force and scanning electron microscopies, Raman spectroscopy and spectroscopic ellipsometry. Unusual low pressure deposition condition (0.40 Pa) was achieved by using a separated argon inlet directed to the Ga target surface, resulting in improved crystalline quality of the films. In this condition, the preferential crystalline orientation, the surface morphology and the optical gap of the GaN films show a strong dependence on the RF power applied to the Ga target, where low RF power (30-60 W) was responsible for increasing the c-axis orientation and the optical gap, while higher RF power (75-90 W) decreased the overall crystal quality and increased the surface roughness.
GROWTH OF GaN FILMS ON GaAs ( 100 ) SUBSTRATE BY RF-SPUTTERING AND E-BEAM EVAPORATOR TECHNIQUES
2016
This work studies the structure, morphology and optical properties of GaN layer grown on porous GaAs/GaAs substrate by radio frequency (RF) sputtering and electron beam (e-beam) evaporation. For comparison, the GaN layer was also grown directly on GaAs substrate and nitride based buffer layers, i.e. aluminum nitride (AlN) and titanium nitride (TiN). In the first part of this work, the best parameters used to obtain good quality porous GaAs on GaAs substrate with uniform distribution and density were determined. It was found that uniform distribution and high density of pores can be fabricated with a mixed solution of dimethylformamide (DMF) and sulphuric acid (H2SO4) with 75% DMF concentration for 10 minutes, at a current density of 250 mA/cm. In the next stage, the GaN layer was grown separately on different surfaces using RF-sputtering and e-beam evaporation. The evidence of Ga-N bondings inside the GaN layer was observed by XPS measurement. Overall, the GaN layers grown by RF-spu...