Full-width At Half-maximum Values Research Articles

Technical Note: Robust measurement of the slice-sensitivity profile in breast tomosynthesis.

The purpose of this work is to improve the repeatability of the measurement of the slice-sensitivity profile (SSP) in reconstructed breast tomosynthesis volumes. A grid of aluminum ball-bearings (BBs) within a PMMA phantom was imaged on breast tomosynthesis systems from three different manufacturers. The full-width half-maximum (FWHM) values were measured for the SSPs of the BBs in the reconstructed volumes. The effect of transforming the volumes from a Cartesian coordinate system (CCS) to a cone-beam coordinate system (CBCS) on the variability in the FWHM values was assessed. Transforming the volumes from a CCS to a CBCS before measuring the SSPs reduced the coefficient of variation (COV) in the measurements of FWHM in repeated measurements by 56% and reduced the dependence of the FWHM values on the location of the BBs within the reconstructed volume by 76%. Measuring the SSP in the volumes in a CBCS improves the robustness of the measurement.

Analisis Pemilihan Region of Interest (RoI) pada Magnetic Resonance Spectroscopy (MRS)

Background: Magnetic Resonance Spectroscopy (MRS) is an advance examination of MRI which produces a spectra describes metabolic information of tissues. ROI setting was very important in producing the spectra with diagnostic value that called Full-Width at Half Maximum (FWHM). In clinical applications, Radiographers select several ROIs in obtaining FWHM values without any specific benchmark which in turn directly affects on the accuracy of staging brain tumor. This study aims to examine the FWHM profiles based on the ROI selections, and to determine the effect of selected ROIs to FWHM values.Methods: This research was a quantitative study with an experimental approach. Data were assessed by an expert Radiographer during a period of 30 days on June 2016 in Radiology Department of Siloam Kebon Jeruk Jakarta Hospital using a specific bottle phantom MRI 2000 ml. The phantom was scanned with 1.5 Tesla MRI scanner, wuth various selection of the ROIs sized 20 mm, 25 mm, 30 mm, 35 mm and 40 mm at the centre position, 12 o'clock position, 3 o'clock position, 6 o'clock position and 9 o'clock position. Data was analyzed using linier regression test of SPSS V.16 software. The confident interval of influence of the ROI size in producing FWHM values was 95%.Results: The results showed the optimum FWHM values, 12-20, produced from the ROI size of 20-30 mm at the centre position. Regression analysis showed significant result (p-value 0.05), which was null hypothesis was rejected. It can be concluded that the ROI size setting effected on the resulted FWHM values. The smaller ROI size, FWHM value will decrease with higher homogeneity and vise versa.Conclusion: Optimum FWHM value was produced by ROI size of 20 – 30 mm at the centre position. There was influence of ROI size setting to FWHM value.

Investigation of K X-ray intensity ratios of some 4d transition metals depending on the temperature

In this paper, we have studied the intensity ratios Kβ/Kα depending on the temperature for transition elements Mo, Nb, Zr and Y by 59.5keV γ-rays from a 100 mCi 241Am radioisotope point source. The Kα and Kβ emission spectra of Mo, Nb, Zr and Y were measured by using a Si (Li) solid-state detector at temperature between 40 and 400°C. σKα and σKβ production cross-sections, Kβ/Kα intensity ratios, asymmetry factor, energy shifts and full width half maximum (FWHM) values of the elements have been calculated. Temperature-dependent changes of the parameters are tabulated and given in the graphical forms. Based on the results obtained, Kβ/Kα X-ray intensity ratios of the elements are dependent on the temperature. It is shown that σKβ fluorescence cross sections of Mo, Nb and Zr have more increase rate than σKα fluorescence cross sections with increasing temperature. For Y, σKα and σKβ production cross-sections firstly decrease, then increase. In general, Kβ/Kα X-ray intensity ratios tend to increase with increasing temperature. Some significant shifts are observed in Kα and Kβ emission spectra of Mo and Y. These results may contribute to the XRF studies of transition metals.

Development of a Thin, Double-Sided Alpha/Beta Detector for Surface-Contamination Measurement

Low-level radioactive surface-contamination measurements require lightweight, large-area, and high-efficiency detectors. In the previous work, we utilized wavelength shifting (WLS) fibers, coupled to a beta-sensitive plastic scintillator (PS) layer on one side, and to an alpha-sensitive ZnS(Ag) layer on both sides, for detecting both alpha and beta particles. In this work, the main goal was to improve the light collection (maximizing the number of photons reaching the PMT) by optimizing the WLS fibers structure, for getting better signal-to-noise ratio and to minimize the low-energy threshold of the detector. In most cases, improving the light collection mostly influenced the detector resolution. In our case, improving the light collection will improve the detection efficiency by ability to detect more events at low-energy spectrum, which is limited by the noise level. Aiming to improve the scintillation light-collection efficiency, we investigated and compared four different detector configurations. Two of them described in the previous work presents utilization of WLS fibers, with different diameters ( $1~\hbox{mm}\phi $ , $1.5~\hbox{mm}\phi $ ), coupled on the PS. Two other configurations present utilization of WLS fibers ( $1.5~\hbox{mm}\phi $ ) installed into a flat groove on the PS layer, while in one configuration we utilized straight WLS fibers and in the other we utilized bent WLS fibers. It was found that the utilization of WLS fibers in bent configuration gives the highest light-collection efficiency. Additionally, there is improved light collection achieved by using WLS fibers with wider diameter ( $1.5~\hbox{mm}\phi $ ), which maximizes the capture fraction. Additionally, since ZnS(Ag) and PS have different decay times (200 ns and 2.4 ns, respectively), we were able to separate alpha from beta events. An algorithm script was developed to calculate the full width at half maximum (FWHM) of each pulse and a histogram was generated of the FWHM values for the pulse shape discrimination (PSD). Efficient PSD was achieved for alpha energies above 100 keV with figure of merit (FOM) of 1.92. GEANT4 simulation was carried out and compared with experimental results. The results of both were matched, showed that the light-collection efficiency from the bent WLS fibers configuration was the best. The simulation results and the experiments, including full description of the detector structure, ionization stage, and the WLS light collection, are presented.

Photoluminescence of localized excitons in ZnCdO thin films grown by molecular beam epitaxy

Abstract We have investigated the luminescence characteristics of Zn 1− x Cd x O thin films with different Cd contents grown by molecular beam epitaxy system. The temperature-dependent photoluminescence (PL) and excitation power-dependent PL spectra were measured to clarify the luminescence mechanisms of the Zn 1− x Cd x O thin films. The peak energy of the Zn 1− x Cd x O thin films with increasing the Cd concentration is observed as redshift and can be fitted by the quadratic function of alloy content. The broadened full-width at half-maximum (FWHM) estimated from the 15 K PL spectra as a function of Cd content shows a larger deviation between the experimental values and theoretical curve, which indicates that experimental FWHM values are affected not only by alloy compositional disorder but also by localized excitons occupying states in the tail of the density of states. The Urbach energy determined from an analysis of the lineshape of the low-energy side of the PL spectrum and the degree of localization effect estimated from the temperature-induced S-shaped PL peak position described an increasing mean exciton-localization effects in ZnCdO films with increasing the Cd content. In addition, the PL intensity and peak position as a function of excitation power are carried out to clarify the types of radiative recombination and the effects of localized exciton in the ZnCdO films with different Cd contents.

MBE-Grown CdTe Layers on GaAs with In-assisted Thermal Deoxidation

Molecular beam epitaxy (MBE) growth of thin (∼2 μm) CdTe layers characterized by high crystal quality and low defect density on lattice mismatched substrates, such as GaAs and Si, has thus far been difficult to achieve. In this work, we report the effects of in situ thermal deoxidation under In and As4 overpressure prior to the CdTe growth on epiready GaAs(211)B wafers, aiming to enhance CdTe crystal quality. Thermally deoxidized GaAs samples were analyzed using in situ reflection high energy electron diffraction, along with ex situ x-ray photo-electron spectroscopy (XPS) and atomic force microscopy. MBE-grown CdTe layers were characterized using x-ray diffraction (XRD) and Everson-type wet chemical defect decoration etching. We found that In-assisted desorption allowed for easier surface preparation and resulted in a smoother surface compared to As-assisted surface preparation. By applying In-assisted thermal deoxidation to GaAs substrates prior to the CdTe growth, we have obtained single crystal CdTe films with a CdTe(422) XRD rocking curve with a full-width half-maximum value of 130.8 arc-s and etch pit density of 4 × 106 cm−2 for 2.54 μm thickness. We confirmed, by XPS analysis, no In contamination on the thermally deoxidized surface.

Synthesis of Large-Area WS2 monolayers with Exceptional Photoluminescence.

Monolayer WS2 offers great promise for use in optical devices due to its direct bandgap and high photoluminescence intensity. While fundamental investigations can be performed on exfoliated material, large-area and high quality materials are essential for implementation of technological applications. In this work, we synthesize monolayer WS2 under various controlled conditions and characterize the films using photoluminescence, Raman and x-ray photoelectron spectroscopies. We demonstrate that the introduction of hydrogen to the argon carrier gas dramatically improves the optical quality and increases the growth area of WS2, resulting in films exhibiting mm2 coverage. The addition of hydrogen more effectively reduces the WO3 precursor and protects against oxidative etching of the synthesized monolayers. The stoichiometric WS2 monolayers synthesized using Ar + H2 carrier gas exhibit superior optical characteristics, with photoluminescence emission full width half maximum (FWHM) values below 40 meV and emission intensities nearly an order of magnitude higher than films synthesized in a pure Ar environment.

低エネルギーX線を用いた斜入射小角X線散乱法によるブロック共重合体薄膜のミクロ相分離構造の深さ依存性と配向挙動の解析

In this review, we demonstrated grazing-incidence small-angle X-ray scattering (GISAXS) measurement with tender X-ray to achieve depth-resolved structure analysis of block copolymer systems, polystyrene-b-poly (2-vinylpyridine)(S2VP) and poly (methyl methacrylate)-b-poly (n-butyl acrylate) thin films (approximately 300 - 400 nm in thick). In the case of using tender X-rays, the penetration depth of X-rays in the vicinity of critical angle of total reflection becomes gentle as compared to the case of using hard X-rays. Herein, X-ray energies of 2.40 keV and 4.36 keV were employed to conduct depth-resolved structure analysis. The experimental full width at half maximum (FWHM) magnitudes of a diffraction spot was investigated to estimate the penetration depth. The incident angle dependence of experimental FWHM magnitudes indicated the same tendency as the FWHM values calculated with Laue function considering attenuation decay, meaning that the penetration depth was controlled by varying incident angles. Depth-resolved structure analysis revealed that in the case of the completely oriented thin film, micro-phase separated structures slightly deformed along the depth direction in the inside of the thin film and the deformation gradually relaxed near the surface.

Structural properties of GaN layers grown on Al2O3 (0001) and GaN/Al2O3 template by reactive radio-frequency magnetron sputter epitaxy

GaN single-crystalline layers were grown by reactive radio-frequency magnetron sputter epitaxy using N2/Ar ambient gas and Ga target. The GaN layers were grown directly on Al2O3 (0001) substrates and GaN/Al2O3 templates. The crystalline quality and the surface morphology of GaN layer depending on substrate temperature and N2 composition ratio, were measured. The crystalline quality of GaN layer was improved by increasing substrate temperature and also decreasing N2 composition ratio. The full-width at half-maximum (FWHM) value of X-ray rocking curve (XRC) of GaN layer grown on Al2O3 at 900 °C and 6% N2, was 27 and 338 arcsec for highly c-axis oriented columnar domains and disordered structure inside the GaN layer, respectively, for (0002) plane. The FWHM values of XRCs of the GaN layers on GaN/Al2O3 for both (0002) and (101̅2) planes, decreased with the increase of substrate temperature, and at above 890 °C they were similar to those of the metal-organic vapor phase epitaxy-grown GaN template, which were approximately 300 and 310 arcsec, respectively. The threading dislocation densities were also estimated using the FWHM values of XRCs, and those of GaN layers on GaN/Al2O3 were considerably decreased as compared with those on Al2O3 at substrate temperatures more than 890 °C.

Tailoring color emissions from N-doped graphene quantum dots for bioimaging applications

Unlike inorganic quantum dots, fluorescent graphene quantum dots (GQDs) display excitation-dependent multiple color emission. In this study, we report N-doped GQDs (N-GQDs) with tailored single color emission by tuning π-conjugation degree, which is comparable to the inorganic quantum dot. Starting from citric acid and diethylenetriamine, as prepared N-GQDs display blue, green, and yellow light emission by changing the reaction solvent from water, dimethylformamide (DMF), and solvent free. The X-ray photoelectron spectroscopy, ultraviolet-visible spectra results clearly show the N-GQDs with blue emission (N-GQDs-B) have relatively short effective conjugation length and more carboxyl group because H2O is a polar protic solvent, which tends to donate proton to the reagent to depress the H2O elimination reaction. On the other hand, the polar aprotic solvent (DMF) cannot donate hydrogen, the elimination of H2O is promoted and more nitrogen units enter GQD framework. With the increase of effective π-conjugation length and N content, the emission band of N-GQDS red-shifts to green and yellow. We also demonstrate that N-GQDs could be a potential great biomarker for fluorescent bioimaging. Nitrogen-doped graphene quantum dots emitting blue, green, or yellow light are promising biomarkers for fluorescence bioimaging. Dan Qu and colleagues in China tailored the emission color of the quantum dots by changing the reaction solvent used in their fabrication. Dots prepared from protic solvent-emitted blue (450 nm) light, those prepared with aprotic solvent emitted green (550 nm), and solvent-free dots emitted yellow (580 nm). The emission colors were pure and narrow band with full-width half-maximum values of 71, 86, and 111 nm and decay lifetimes of 14, 13, and 10 ns, respectively. Imaging experiments with a confocal fluorescence microscope and A549 cells labeled with the graphene dots demonstrated that the cells did indeed become brightly illuminated with visible colors when optically excited, suggesting that the graphene dots are suitable for bioimaging.

Coalescence of few layer graphene grains grown by chemical vapor deposition and their stacking sequence

Abstract

Germanium - the superior dopant in n-type GaN

We present an experimental study about the influence of Si and Ge doping in GaN with focus on the occurring strain levels and overall crystalline quality. Extremely high quality samples were examined by means of Raman spectroscopy, demonstrating effective, n-type doping concentrations up to the 5 × 1019 cm–3 regime. By studying the full width at half maximum (FWHM) of the E2(high) Raman mode with rising doping concentration, Ge is approved as the by far superior dopant if compared to Si. Even elevated nominal Ge concentrations yield corresponding FWHM values of just 3 cm–1, a most competitive value even for bare bulk GaN samples. At the same time, the biaxial, compressive stress that is introduced by such high Ge doping amounts to just 0.2 GPa, in clear contrast to the particular case of silicon. Here, even moderate doping levels lead to tensile stress up to 1 GPa and consequently to a serious degeneration of the overall crystal quality as approved by our Raman analysis. Additionally, the examined high doping concentrations enable the observation of longitudinal optical phonon plasmon (LPP) modes in the Raman spectra, which serve as a direct tool for the determination of the effective doping concentration. A careful analysis of the LPP coupling at cryogenic and room temperature yields within the error interval identical free carrier concentrations in all germanium doped samples, pointing towards an energetically shallow nature of the dopant. (© 2015 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)

InAs avalanche photodiodes as X-ray detectors

We designed and demonstrated an InAs avalanche photodiode (APD) for X-ray detection, combining narrow band gap semiconductor materials and avalanche gain from APDs. The InAs APD (cooled by liquid nitrogen) was tested with a 55Fe X-ray source. Full width at half maximum (FWHM) from the spectra decreases rapidly with reverse bias, rising again for higher voltages, resulting in a minimum FWHM value of 401 eV at 5.9 keV. This minimum value was achieved at 10 V reverse bias, which corresponds to an avalanche gain of 11. The dependence of FWHM on reverse bias observed is explained by the competition between various factors, such as leakage current, capacitance and avalanche gain from the APD, as well as measurement system noise. The minimum FWHM achieved is largely dominated by the measurement system noise and APD leakage current.

Synthesis of few layer single crystal graphene grains on platinum by chemical vapour deposition

The present competition of graphene electronics demands an efficient route which produces high quality and large area graphene. Chemical vapour deposition technique, where hydrocarbons dissociate in to active carbon species and form graphene layer on the desired metal catalyst via nucleation is considered as the most suitable method. In this study, single layer graphene with the presence of few layer single crystal graphene grains were grown on Pt foil via chemical vapour deposition. The higher growth temperature changes the surface morphology of the Pt foil so a delicate process of hydrogen bubbling was used to peel off graphene from Pt foil samples with the mechanical support of photoresist and further transferred to SiO2/Si substrates for analysis. Optical microscopy of the graphene transferred samples showed the regions of single layer along with different oriented graphene domains. Two type of interlayer stacking sequences, Bernal and twisted, were observed in the graphene grains. The presence of different stacking sequences in the graphene layers influence the electronic and optical properties; in Bernal stacking the band gap can be tunable and in twisted stacking the overall sheet resistance can be reduced. Grain boundaries of Pt provides low energy sites to the carbon species, therefore the nucleation of grains are more at the boundaries. The stacking order and the number of layers in grains were seen more clearly with scanning electron microscopy. Raman spectroscopy showed high quality graphene samples due to very small D peak. 2D Raman peak for single layer graphene showed full width half maximum (FWHM) value of 30cm−1. At points A, B and C, Bernal stacked grain showed FWHM values of 51.22, 58.45 and 64.72cm−1, while twisted stacked grain showed the FWHM values of 27.26, 28.83 and 20.99cm−1, respectively. FWHM values of 2D peak of Bernal stacked grain showed an increase of 20–30cm−1 as compare to single layer graphene which showed its dispersive nature and confirmed Bernal sequence. On the other hand, the slightest decrease in FWHM values of 2D peak in twisted grain comparing to single layer confirmed the twisted sequence of grains. Atomic force microscopy analysis showed an increasing trend in grain height profile with an increase in the number of layers.

Texture of the nano-crystalline AlN thin films and the growth conditions in DC magnetron sputtering

DC reactive magnetron sputtering technique has been used for the preparation of AlN thin films. The deposition temperature and the flow ratio of N2/Ar were varied and subsequent dependency of the films crystallites orientation/texture has been addressed. In general, deposited films were found hexagonal polycrystalline with a (002) preferred orientation. The X-ray diffraction (XRD) data revealed that the film crystallinity improves, with the increase of substrate temperature from 300°C to 500°C. The dropped in full width half maximum (FWHM) of the XRD rocking curve value further confirmed it. However, increasing substrate temperature above 500°C or reducing the nitrogen condition (from 60 to 30% in the environment) induced the growth of crystallites with (102) and (103) orientations. The rise of rocking curve FWHM for the corresponding conditions depicted that the films texture quality deteriorated. A further confirmation of the variation in film texture/orentation with the growth conditions has been obtained from the variation in FWHM values of a dominant E1 (TO) mode in the Fourier transform infrared (FTIR) spectra and the E2 (high) mode in Raman spectra. We have correlated the columnar structure in AFM surface analyses with the (002) or c-axis orientation as well. Spectroscopic ellipsometry of the samples have shown a higher refractive index at 500°C growth temperature.

Prepare core–multishell CdSe/ZnS nanocrystals with pure color and controlled emission by tri-n-octylphosphine-assisted method

Core–multishell semiconductor nanocrystals have great potential in light emitting devices (LEDs) display, fluorescent biomarkers and luminescent solar concentrators. However, their applications are strongly limited due to the wide full-width at half-maximum (FWHM), inaccurate controllable emission wavelength, and decreased quantum yield as the shell coverage growth. So there still remains a great challenge for improving the photoluminescence properties of core–multishell quantum dots. In this work, tri-n-octylphosphine (TOP) assisted method was used to prepare CdSe/ZnS QDs with narrow FWHM and controlled emission wavelength, the influence of experimental conditions on the photoluminescent properties of the core–multishell QDs were investigated. The experimental results indicated this is an effective method to prepare core–multishell QDs with pure color emission (FWHM value is smaller than 25nm after coating with 3 monolayers of ZnS), accurately controlled emission and high QY (>95%). This is the smallest FWHM for core–multishell QDs. The emission wavelength of the as-prepared core–multishell QDs can be continuously tuned by simply varying the emission of the core nanocrystals. Furthermore, the knowledge gained in this study enabled us to better understand the mechanism of TOP-assisted method and provide a promise way for light emitting diodes-backlit display with high color saturation.

Effect of Al substrate nitridation on the properties of AlN films grown by pulsed laser deposition and its mechanism

AlN films have been grown on nitrided and non-nitrided Al substrates by pulsed laser deposition (PLD) technology at 450°С. The surface morphology, crystalline quality, and interfacial property of the as-grown AlN films on nitrided and non-nitrided Al substrates have been investigated systematically. It is found that the as-grown ∼300nm-thick AlN films on nitrided Al substrates show the very smooth surface with a root-mean-square (RMS) surface roughness of 1.5nm, high crystalline quality with full-width at half-maximum (FWHM) values for AlN(0002) and AlN(10−12) X-ray rocking curves (XRCs) of 0.6° and 0.9°, and sharp and abrupt interfaces. These results are in striking contrast to those of ∼300nm-thick AlN films grown on non-nitrided Al substrates. The as-grown ∼300nm-thick AlN films on non-nitrided Al substrates show relatively rough surface with a RMS surface roughness of 4.0nm, poor crystalline quality with FWHM values for AlN(0002) and AlN(10−12) XRCs of 1.1° and 1.5°, and a ∼1.5nm-thick interfacial layer. Based on the characterizations, the effect of Al substrates nitridation and the growth mechanism of AlN films grown on nitrided Al substrates by PLD are hence proposed. This work provides an effective approach for the growth of high-quality AlN films on Al substrates for the future application of AlN-based devices.

Correlation Between Epitaxial Layer Quality and Drain Current Stability of GaN/AlGaN/GaN Heterostructure Field-Effect Transistors

Stability of current-voltage characteristics was investigated for GaN/AlGaN/GaN heterostructure field-effect transistors, which were fabricated using epiwafers with different yellow luminescence (YL)-to-band edge (BE) ratios in photoluminescence spectrum and full-width at half-maximum (FWHM) values of X-ray rocking curves. After application of a long-term high-voltage OFF-state stress, they exhibited a temporary reduction of drain current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> ) accompanied by a positive threshold voltage shift with a long recovery time (>1 h at room temperature). To study the mechanism of this instability, transient of Id just after removing the stress was measured under the subthreshold condition for different ambient temperatures (-20 °C to 200 °C). An isothermal capacitance transient spectroscopy-like analysis applied to the transient signal indicated that electron traps with an activation energy of 0.3-0.5 eV and a density of the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> are responsible for this phenomenon. The emission rate of these electron traps increased when the YL/BE ratio was reduced, while the trap density decreased when the FWHM values were reduced. These results suggest that the long-term Id transient can be minimized by reducing both of these parameters.

R면 사파이어 위에 HVPE로 성장된 a면 GaN 에피층의 성장온도 효과 및 1000℃에서의 V/III족 비의 효과

The effects of the growth temperature on the properties of a-plane GaN epi-layer on r-plane sapphire by HVPE were studied, when the constant V/III ratio and the flow rate of HCl for the Ga source channel was fixed at 10 and 700 sccm, respectively. Additionally the effects of V/III ratios for source gasses were studied when growth temperature and the flow rate of HCl for the Ga source channel was fixed at 1000 C and 700 sccm, respectively. As the growth temperature was increased, the values of Full Width Half Maximum (FWHM) for Rocking curve (RC) of a-plane GaN (11-20) epi- layer were decreased and thickness of a-plane GaN epi-layer were increased. As V/III ratios were increased at 1000 C, the values of FWHM for RC of a-plane GaN (11-20) were declined and thickness of a-plane GaN epi-layer were increased. The a-plane GaN (11-20) epi-layer grown at 1000 C and V/III ratio = 10 showed the lowest value FWHM for RC of a- plane GaN (11-20) for 734 arcsec and the smallest dependence of Azimuth angle for FWHM of (11-20) RCs.

Effects of the group V/III ratio and a gan inter-layer on the crystal quality of InN grown by using the hydride vapor-phase epitaxy method

The hydride vapor-phase epitaxy (HVPE) method was used to deposit high-quality InN layers on GaN inter-layer/sapphire (0001) structures that had been fabricated by using either the HVPE method or the metal-organic chemical-phase deposition (MOCVD) method. The effects of the group V/III ratio and different GaN inter-layers on the crystal quality of the InN layers were systemically investigated. The InN layer grown at a low Group V/III ratio revealed a high crystal quality with a two-dimensional (2D) growth mode. Also, the 110.7-nm-thick InN layer grown by using HVPE on a GaN inter-layer/sapphire (0001) substrate structure that had been fabricated by using MOCVD had a high crystal quality, with the full width at half maximum (FWHM) of the InN X-ray diffraction (XRD) peak being about 844 arcsec, and a smooth surface with an atomic force microscopy (AFM) roughness of about 0.07 nm. On the other hand, the 145.7-nm-thick InN layer grown by using HVPE on a GaN inter-layer/sapphire (0001) substrate structure that had been fabricated by using the HVPE method had a lower crystal quality, a FWHM value for the InN (0002) peak of about 2772 arcsec, and a surface roughness of about 3.73 nm. In addition, the peak of the E2 (high) phonon mode for the 110.7-nm-thick InN layer grown by using HVPE on a GaN inter-layer/sapphire (0001) structure that had been fabricated by using MOCVD was detected at 491 cm -1 and had a FWHM of 9.9 cm-1. As a result, InN layers grown by using HVPE on GaN inter-layer/sapphire (0001) substrate structures fabricated by using MOCVD have a high crystal quality and a reduced Raman value, which agrees well with the results of the XRD analysis.