X-ray Rocking Curve Measurements Research Articles

高純度ダイヤモンド単結晶の合成 ＩＩ

High purity synthetic diamond crystals (type IIa) grown by the temperature gradient method with impurities less than 0. 1 ppm were studied on the crystal defects and residual strains in details by polarizing microscopy, double-crystal X-ray rocking curve measurement, X-ray topography and Raman spectroscopy. The results indicated that the synthetic type IIa diamonds had less crystal defects and lower residual strain than natural diamonds or synthetic type I b diamonds did. Furthermore it was found that some of dislocations in the synthetic type IIa diamond could be removed and the crystal quality of the diamonds could be improved by using strain-free and low defect crystals for the seeds.

A Study of Low-Temperature Grown Gap by Gas-Source Molecular Beam Epitaxy

AbstractWe report the effects of growth conditions on the strain and crystalline quality of lowtemperature (LT) grown GaP films by gas-source molecular beam epitaxy. At temperatures below 160 °C, poly-crystalline GaP films are always obtained, regardless of the PH3 low rate used, while at temperatures above 160 °C, the material quality is affected by the PH3 flow rate. Contrary to compressively strained LT GaAs, high-resolution X-ray rocking curve measurement indicates a tensile strain of the LT GaP films, which is considered to be due to PGa antisite defects. The strain is found to be affected by the PH3 flow rate, the growth temperature, and post-growth annealing. Contrary to LT GaAs, no P precipitates are observed in cross-sectional transmission electron microscopy.

Ion-beam-induced epitaxial crystallisation of metastable Si 1− x−yGe xC y layers fabricated by Ge and C ion implantation

Formation of metastable Si 1− x−y Ge x C y layers ( x = 0.13 and y = 0.014 at peak concentration) on Si(100) has been performed by high-dose implantation of 80 keV Ge and 17 keV C ions and subsequent ion-beam-induced epitaxial crystallisation (IBIEC) with 400 keV Ar or Ge ion bombardments at 300–400°C. Their structural properties are compared with those of Si 1− x−y Ge x C y layers grown by solid phase epitaxial growth (SPEG) up to 700°C. Crystalline growth by IBIEC has shown a larger growth rate in Si 1−x−y Ge x C y Si than in Si 1−x Ge x Si with the same Ge concentration for all bombardments under investigation. Depth profiles of implanted atoms observed by SIMS measurements have revealed almost the same profiles for Ge and C atoms after IBIEC process. X-ray rocking curve measurements have shown a strain-compensated growth of Si 1−x−y Ge x C y Si by IBIEC, whereas it has been suggested that Si 1−x−y Ge x C y Si layers crystallised by SPEG have both compressive and tensile strains.

Structural characterization of ion-beam-induced epitaxially crystallized thin layers of III–V and IV–IV semiconductors

Structural properties of ion-beam-induced epitaxial crystallization (IBIEC) for amorphous layers of GaAs on GaAs(100), BP on BP(100) and Si 1− x Ge x and Si 1− x− y Ge x C y on Si(100) have been investigated. Crystallization was induced by ion bombardment with 400 keV Ne, Ar or Kr at 150 °C for GaAs and at 350 °C for BP. Epitaxial crystallization up to the surface was observed both in GaAs and BP at temperatures much below those required for the solid phase epitaxial growth (SPEG). The growth rate per nuclear energy deposition density has shown a larger dependence on ion dose rate in cases of heavier ion bombardments both for GaAs and BP. Crystallization of a-GaAs with ions whose projected ranges are within the amorphous layer thickness was also observed at 150 °C. Epitaxial crystallization of Si 1− x Ge x and Si 1− x− y Ge x C y layers ( x = 0.13 and y = 0.014 at peak concentration) on Si(100) formed by high-dose implantation of 80 keV Ge and 17 keV C ions has been observed in the IBIEC process with 400 keV Ar ion bombardments at 300–400 °C. Crystalline growth by IBIEC has shown a larger growth rate in Si 1−x−yGe xC y Si} than in Si 1−xGe x Si} with the same Ge concentration for all bombardments under investigation. X-ray rocking-curve measurements have shown a strain-compensated growth in Si 1−x−yGe xC y Si} , whereas Si 1−xGe x Si} samples have shown a growth with strain accommodation.

MBE Growth of YbTe on GaAs(100) and BaF2(111) Substrates

The structural properties of MBE grown YbTe layers were investigated by X-ray dichractioii methods and photoluminescence measurements. YbTe films were grown oii the ZnTe and CdTe bucher layers crystallised oii the GaAs(100) 2° off oriented substrates and on the BaF2(100) substrates. In the case of GaAs substrates the two-dimensional growth mode of YbTe was observed on reflectioii high energy electron diffraction picture. Results of the X-ray rocking curve and photoluminescence excitation measurements indicate that the structural properties of YbTe films are ckparable to the properties of the MBE grown ZnTe and CdTe layers oii the GaAs(100) substrates. The measured values of the YbTe lattice constant parallel and perpendicular to the growth plane show that the 1 μm thick layers are partially strained. The full width at half maximum values of the X-ray rocking curves are the smallest (900 arc seconds) for the YbTe films crystallised on the 2 μm thick CdTe bucher layer grown on the GaAs(100) substrate. In the case of BaF2(111) substrate the two-dimensional MBE growth mode of YbTe was not observed.

Chemical beam epitaxy and laser-modified chemical beam epitaxy of InGaAs using tris-dimethylaminoarsenic

The growth of InxGaj1−xAs (x = 0.13–0.25) on GaAs by chemical beam epitaxy (CBE) and laser-modified CBE using trimethylindium (TMIn), triethylgallium (TEGa), and tris-dimethylaminoarsenic (TDMAAs) has been studied. Reflection high-energy electron diffraction measurements were used to investigate the growth behavior of InGaAs at different conditions. X-ray rocking curve and lowtemperature photoluminescence (PL) measurements were used to characterize the InGaAs/GaAs pseudomorphic strained quantum well structures. Good InGaAs/GaAs interface and optical property were obtained by optimizing the growth condition. As determined by the x-ray simulation, laser irradiation during the InGaAs quantum well growth was found to enhance the InGaAs growth rate and reduce the indium composition in the substrate temperature range studied, 440–500°C, where good interfaces can be achieved. These changes, which are believed to be caused by laser-enhanced decomposition of TEGa and laser-enhanced desorption of TDMAAs, were found to depend on the laser power density as well. With laser irradiation, lateral variation of PL exciton peaks was observed, and the PL peaks became narrower.

Molecular beam epitaxy growth and properties of GaN films on GaN/SiC substrates

Two types of nitrogen plasma sources, an electron cyclotron resonance (ECR) plasma source and a radio frequency (rf) plasma source, were used for the growth of GaN by molecular beam epitaxy (MBE). GaN film quality was correlated with the optical emission characteristics of each type of nitrogen plasma source employed. The best quality GaN films were those grown using the rf nitrogen plasma source. This source was found to emit a much larger fraction of atomic nitrogen and 1st-positive series excited molecular nitrogen in contrast to the ECR plasma source which mainly produced 2nd-positive series excited molecular nitrogen and nitrogen molecular ions when operated under the same conditions. The benefit of homoepitaxial growth of GaN, using metalorganic vapor phase epitaxy grown GaN layers on basal plane 6H-SiC, was seen by the observation of surface reconstructions before, during, and after GaN film growth by MBE. In addition, the MBE-grown GaN films exhibited remarkably intense photoluminescence dominated by a sharp band-edge peak at 3.409 eV having a full-width at half-maximum (FWHM) of 29.7 meV at room temperature. At lower temperatures, splitting of the near-edge excition peaks was observed. Double-crystal x-ray rocking curve measurements of selected MBE-grown GaN films yielded (0002) diffraction peaks having FWHMs as narrow as 156 arcsec.

X-ray curve characterization of homo-epitaxial layers on silicon deposited after DC hydrogen cleaning

High-resolution X-ray diffraction is a non-destructive method with an extremely high strain sensitivity. It is shown that its sensitivity is high enough to detect the influence of very small degrees of contamination by oxygen at the interface and the influence of H2 incorporation. Interference fringes due to the strain induced by 0.01 monolayer of oxygen between the substrate and epilayer can be observed and distinguished from the H2 incorporation. Depending on the sample preparation, the fit of the X-ray rocking curve measurements is different. Therefore, it is possible to distinguish between interface contamination, which leads to a well-defined strain at the interface, and the strain induced by H2 incorporation, which is smeared out over a large region. Secondary-ion mass spectrometry as well as the cross section transmission electron microscopy measurements were correlated with the high-resolution X-ray diffraction measurements. Additional Rutherford backscattering channelling measurements also confirmed these results.

Growth via Mocvd and Characterization Of GaN and AlxGa1−xN(0001) Alloys for Optoelectronic and Microelectronic Device Applications

ABSTRACTMonocrystalline GaN(0001) thin films have been grown at 950°C on high-temperature, 100 nm thick, monocrystalline AIN(0001) buffer layers previously deposited at 1100°C on α(6H)-SiC(0001)si substrates via MOCVD in a cold-wall, vertical, pancake-style reactor. AlxGa1−xN films (0≤x≤1) were grown directly on the same SiC surface at 1100°C. Abrupt heterojunctions among the alloy composition were demonstrated. All films possessed a smooth surface morphology and were free of low-angle grain boundaries and associated oriented domain microstructures. Double-crystal x-ray rocking curve measurements for the GaN(0004) reflection for simultaneously deposited 1.4 μm films revealed FWHM values of 58 and 151 arcsec for materials grown on on-axis and off-axis material, respectively. The corresponding values for the AIN(0004) buffer layers were ≈ 200 and ≈400 arc sec, respectively. A similar relationship was found for the alloys for 0≤x≤0.2. The PL spectra of the GaN films deposited on both vicinal and on-axis substrates revealed strong bound exciton emission with a FWHM value of 4 meV. The spectra of these films on the vicinal substrates were shifted to a lower energy, indicative of films containing residual tensile stresses. A peak believed to be associated with free excitonic emission was also observed in each on-axis spectrum. Rutherford backscattering, Auger depth profiling and energy dispersive analysis were used to determine the AIN/GaN ratios in the alloys. Cathodoluminescence of solutions with x<0.5 exhibited strong near band edge emission with a FWHM as low as 31 meV. The band gaps were determined via spectral ellipsometry. Undoped GaN and A1xGa1−xN films were too resistive for accurate Hall-effect measurements. Controlled n-type Si-doping in GaN and AlxGa1−xN (for x≤0.4) was achieved for net carrier concentrations ranging from approximately 2×1017 cm−3 to 2×1019 (AlxGa1−xN) or to l × 1020 (GaN) cm−3. Mg-doped, p-type GaN was achieved with nA−nD = 3 × 1017 cm−3, p ≈ 7 Ω cm and μ ≈ 3 cm2/V·s.

スパッタ法によるＳｉ基板上Ｆｅのエピタキシャル成長とその磁気特性

Epitaxial growth of Fe films on Si(l00), Si(110), and Si(111) substrates was achieved by dc facing targets sputtering. The substrate de bias was found to be an important parameter for achieving epitaxial growth. When this bias was not applied, no epitaxial films were obtained except on the Si(111) substrate. Electron diffraction and X-ray rocking curve measurement confirmed that the epitaxial relationship for Fe(111)/Si(111) was B-type (twinned epitaxy). The in-plane anisotropy for Fe(l00)/Si(l00) and Fe(111)/ Si(111) was explained as megnetocrystalline anisotropy. However, the anisotropy for Fe(110)/Si(110) was different from that for bulk Fe.

X-Ray and Electron-Optical Characterization of ZnTe/CdTe and ZnTe/GaAs Epitaxial Layers Obtained by the MBE Method

X-ray diffraction topography (Bragg diffraction) and X-ray rocking curve measurements were used to study the perfection and structural properties of ZnTe epitaxial layers ohs the CdTe and GaAs substrates. ZnTe epitaxial 1ayers on CdTe were grown by MBE method b y using a machine made in the Institute of Physics of the Pofish Academy of Sciences. The ZnTe layers on GaAs were produced on the other, factory-made MBE system. The comparison between the X-ray topographical images of the substrate and epitaxial layer shows that imperfections on the substrate surface cause imperfections in the epitaxial layer. The results of double-crystal diffractometry measurements show that the perfection of the layer on the GaAs substrate is higher than that on the CdTe. The presence of microtwining in the ZnTe layer on the CdTe substrate was confirmed by RHEED measurements. The X-ray standing wave fluorescent spectra were also measured for the samples. PACS numbers: 61.10.—i, 61.14.Hg, 68.55.—a

Growth of ZnS and ZnCdSSe alloys on GaP using an elemental sulfur source by molecular beam epitaxy

MBE growth of ZnS and ZnS-based alloys using an elemental sulfur source is reported. The initial growth process has been investigated by reflection high-energy electron diffraction, and crystalline quality is evaluated by X-ray rocking curve measurement. It is shown that crystalline quality is greatly improved by using ZnS buffer grown at a high substrate temperature. However, the quality of ZnSSe with nearly lattice-matched composition is still not perfect. The results are discussed in terms of relationship between growth process and crystalline quality.

Laser-Modified Chemical Beam Epitaxy of InGaAs/GaAs Multiple Quantum Wells Using Tris-Dimethylaminoarsenic

AbstractWe report for the first time laser-modified chemical beam epitaxy (CBE) of InGaAs/GaAs multiple quantum well (MQW) structures using trimethylindium (TMIn), triethylgallium (TEGa), and tris-dimethylaminoarsenic (TDMAAs), a safer alternative to arsine. X-ray rocking curve (XRC) and low-temperature photoluminescence (PL) measurements were used to characterize the pseudomorphic strained quantum well structures. As determined by the X-ray simulation, laser irradiation during the InGaAs well growth was found to enhance the InGaAs growth rate and reduce the indium concentration in the substrate temperature range studied, 440-S00°C, where good interfaces can be achieved. We attribute these changes to laser-enhanced decomposition of TEGa and laser-enhanced desorption of TDMAAs. With laser irradiation, lateral variation of PL exciton peaks was observed, and the PL peaks became narrower.

Magnetism and structure of YBaCuO superconducting films deposited in unusual geometries using Nd:YAG laser

High quality YBa/sub 2/Cu/sub 3/O/sub 7- delta / thin films have been fabricated by pulsed Nd:YAG laser deposition using an unusual off-axis target-substrate geometry. In this geometry, one can eliminate the deposition of laser droplets. The films are free of particles and have smooth surfaces. The critical temperature (T/sub c/) of these films is in the range of 87-90 K, which is as high as that of on-axis deposited films. From the X-ray rocking curve measurement and the magnetization measurement, no significant differences were found between the on-axis and off-axis laser deposited films.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High-resolution x-ray analysis of strain in low-temperature GaAs.

X-ray-diffraction measurements have been used to characterize GaAs layers grown at low temperature on GaAs substrates by molecular-beam epitaxy. Three ranges of low-temperature growth are defined, labeled as ``low range,'' (less than 260 \ifmmode^\circ\else\textdegree\fi{}C), ``midrange,'' (between 260 and 450 \ifmmode^\circ\else\textdegree\fi{}C), and ``high range,'' (above 450 \ifmmode^\circ\else\textdegree\fi{}C), as measured by a growth-chamber thermocouple. Films grown in the low range are amorphous, those in the midrange are fully strained and lattice matched to the substrate, and those grown above 450 \ifmmode^\circ\else\textdegree\fi{}C are similar to ordinary GaAs. A notable property of the midrange layers is the expansion and contraction of the lattice parameter with thermal anneals up to 900 \ifmmode^\circ\else\textdegree\fi{}C. From x-ray rocking-curve measurements on more than 200 anneal conditions in this group, a growth model based on arsenic antisite defects is proposed.

InxGa(1−x)N/InyGa(1−y)N superlattices grown on GaN films

High-quality In0.22Ga0.78N/In0.06Ga0.94N superlattices were grown on GaN films with periods of 60 and 200 Å by the two-flow metalorganic chemical-vapor deposition method. The double-crystal x-ray rocking curve measurements showed satellite peaks which indicated the existence of the In0.22Ga0.78N/In0.06Ga0.94N superlattices. The quantum effects were observed through room-temperature photoluminescence (PL) measurements. These PL spectra were compared to theoretical solutions for the In0.22Ga0.78N/In0.06Ga0.94N superlattices.

The effect of substrate tilt on MOCVD growth of {100}CdTe on {100}GaAs

Epitaxial layers of CdTe were grown by metalorganic chemical vapor deposition on surfaces of single crystal, {100} GaAs which had been ground, polished, and etched to a spherically shaped done. This dome-shaped surface allowed the morphological and structural properties of the epitaxial CdTe layers to be determined for all 360° of azimuth and up to 15° of polar angle from the [100] axis within a single growth experiment. At two growth temperatures, approximately 275 and 375°C, the results show distinct twofold rotational symmetry in both morphology and crystal perfection as determined by x-ray rocking curve measurement. Surface morphology is superior at azimuths near tilts toward the A pole. Four-sided pyramidal hillocks appear at other azimuths and at 0° tilt; the symmetry of the hillocks diminishes as the tilt increases. The orientations for growth which simultaneously minimize the surface defects and rocking curve full-width half-maximum appear to be at locations on the surface where the surface normal is tilted 3–4° toward the A or B, depending on the temperature regime chosen. Epitaxial layers grown on planar wafers of {100}GaAs tilted toward Ga and As show surface morphology essentially identical to the dome at these orientations. The surface morphology of CdTe growth on GaAs/Si wafers suggests that these layers are tilted toward the B.

Sr/sub 2/AlTaO/sub 6//YBa/sub 2/Cu/sub 3/O/sub 7/ heterostructures for superconducting device applications

Using pulsed laser deposition, the authors have prepared epitaxial heterostructures of a new insulating perovskite Sr/sub 2/AlTaO/sub 6/ (SAT) and the high-temperature superconductor YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) on LaAlO/sub 3/ substrates. X-ray rocking curve and Rutherford backscattering channeling measurements on

The anomalous depth distribution of low dose oxygen and nitrogen ions implanted into silicon

Silicon wafers have been implanted with oxygen and nitrogen ions with an energy of 150 keV in the dose range of 10 16−10 17 cm −2. Implanations were carried out both singly, i.e. just oxygen or just nitrogen, and also doubly, i.e. combinations of oxygen and nitrogen. In the latter case, the sequence of the implantations was varied. The implanted samples were analysed using secondary ion mass spectrometry (SIMS) and the X-ray rocking curve technique. In the double implanted material, when oxygen was implanted before nitrogen, both the impurity distributions were seen to shift deeper than expected into the structure. However, when nitrogen was implanted first, no shift was observed [Wong and Kilner, Mater Sci Engng, B12, 67 (1992)]. For the singly implanted material, the X-ray rocking curve measurements showed that the as-implanted oxygen sample was found to contain stress in the silicon lattice, whereas no stress was detected in the nitrogen implanted sample. This stress also exists in both the doubly implanted samples. However, the amount of stess and the crystalline quality of the material is dependent on the sequence of the double implant and temperature. Increasing the temperature of implantation from 560 to 710°C decreases the anomalous impurity depth distribution, or ‘shift’, in the double implanted sample and the material was found to contain less stress and have a better crystalline quality. The anomalous impurity depth distributions can be explained by the segregation of reactive inpurities on to interstitial defects created during high temperature implantation.

InP and InAsP/InP heterostructures grown on InP (111) B substrates by gas-source molecular beam epitaxy

InP and InAsP/InP heterostructures have been grown on InP (111)B substrates by gas-source molecular beam epitaxy. Specular surface morphology was obtained under growth conditions determined by optimizing the substrate temperature, V/III incorporation ratio and substrate misorientation. High-quality InP homoepitaxial layers and InAsP/InP strained multiple quantum wells were characterized by Nomarski interference contrast image, X-ray rocking curve and low-temperature photoluminescence measurements.