Rocking Curve Analysis Research Articles

高质量掺Mn铝酸锂晶体生长及其光谱特性

The growth of a Mn-doped LiAlO2 single crystal by the Czochralski (CZ) method and the characterization of its spectroscopy and thermoluminescence (TL) are presented. The X-ray rocking curve and chemical etching analysis show that the as-grown crystal has good crystallinity. The full-width at half-maximum (FWHM) of the LiAlO2 (200) \omega rocking curve is 23.2 arcsec and the etching pits density of the (100) plane is (1.6-4.0)x104 cm-2. The transmission spectrum indicates that the crystal is highly transparent in the 200-1500-nm wavelength range. The emission spectrum of the crystal consists of a peak around 579 nm when excited with 428-nm light. The TL spectra show that the LiAlO2:Mn crystal has glow peaks at 150 and 172 °C. The change of TL characteristics of the crystal before and after thermal annealing in the air is discussed, and the effect of annealing and irradiation on the evolution of defect types is analyzed.

MBE Growth and Transfer of HgCdTe Epitaxial Films from InSb Substrates

An investigation of the heteroepitaxial growth of HgCdTe films onto InSb(211)B substrates is reported. High-quality HgCdTe(211)B single-crystal films have been successfully deposited onto InSb(211)B substrates and have been characterized with x-ray diffraction rocking curve analysis, etch pit density analysis, and surface void defect mapping. X-ray rocking curve (422) reflection full-width at half-maximum of 60 arcsec has been obtained for 7-μm-thick x = 0.22 HgCdTe epitaxial films, and etch pit densities of 3 x 10 6 cm -2 to 3 × 10 7 cm -2 have been observed. A significant reduction in HgCdTe void defect densities to 100 cm -2 to 200 cm -2 has been observed on InSb, including a complete absence of large "void cluster" defects that are often observed for growth on CdZnTe. Wafer bow induced by the growth of HgCdTe on InSb is less than 1 μm for 2-inch-diameter substrates. Significant diffusion of In into HgCdTe is observed for HgCdTe/InSb wafers that are subjected to Hg anneals at 250°C to 300°C. A preliminary investigation of the transfer of HgCdTe films from InSb onto Si substrates has also been undertaken, using an adhesive wafer bonding approach evaluated with scanning acoustic microscopy. The infrared transmission characteristics of the bonding adhesive have been investigated with respect to postgrowth annealing procedures to establish the compatibility of the bonding approach with HgCdTe device processing and detector operation.

Morphological and microstructural evolution in the two-step growth of nonpolar a-plane GaN on r-plane sapphire

In this paper, we report a detailed study on the evolution of surface morphology and microstructure of nonpolar a-plane GaN (a-GaN) through controlled growth interruptions. Microscopy imaging shows that the two-step a-GaN growth went through a roughening-recovery process. The first-step growth (under high V/III and high pressure) produced a rough surface with tall mesas separated by voids. The second-step growth (under low V/III and low pressure) promoted the lateral growth and filled up the voids. Striations that formed during the island coalescence persisted throughout the second-step growth, but could be relieved by an additional third-step growth. The morphological evolution was explained according to the kinetic Wulff plots. The microstructure of the a-GaN films was investigated by transmission electron microscopy (TEM) and x-ray rocking curve analysis. Most of the extended defects observed in the plan-view TEM images were I1 type basal-plane stacking faults (BSFs) and their associated partial dislocations (PDs). It is found that the bending of PDs (at the inclined/vertical growth fronts) within the basal plane toward the m-axes was responsible for the substantial reduction in threading PDs and the increase in BSF dimension. Based on a careful correlation between the morphological evolution and the microstructure development, we proposed a model explaining the possible mechanisms for the great reduction in defect density during the two-step growth process.

Seeded growth of AlN bulk crystals in m- and c-orientation

Seeded growth of AlN boules was achieved on m-(1 0 1¯ 0) and c-(0 0 0 1¯) orientations by physical vapor transport (PVT). The single crystalline m- and c-plane seeds were cut from freestanding AlN single crystals. AlN boules 12 mm in diameter and 7 mm in height were grown at source temperatures around 2280 °C in N 2 atmosphere at 500 Torr of total pressure. Under identical process conditions, the m- and c-plane boules exhibited the same growth rates, 150–170 μm/h, and similar expansion angles, 22–27°, which indicated that the growth was controlled by the thermal profile inside the crucible rather than by crystallographic differences. X-ray rocking curve analysis and Raman spectroscopy confirmed that both m- and c-plane grown crystals possessed high crystalline quality. The dislocation density in both crystals was non-uniform and in the range 10 2–10 5 cm −2, as characterized by X-ray topography.

Structural changes in Si crystals exposed to chemical etching and ion implantation

AbstractResults of X‐ray diffraction studies on structural changes in Si crystals caused by chemical etching for 40 s in HF, HNO3 solution and phosphorus‐ion implantation with the energy E = 100 keV and dose D = 8 × 1014 cm−2 are represented.Two‐ and three‐crystal X‐ray diffractometry methods are used for a quantitative assessment of structural changes occurring in the near‐surface crystal layers. Analysis of experimental rocking curves was made with the use of different approaches developed on the basis of kinematic and dynamic theory of X‐ray scattering in the imperfect crystals. A model of possible system of structural defects in the near‐surface silicon layers modified by chemical etching and ion implantation is proposed. The model accounts for the availability of respective sizes and concentrations of spherical and disc‐shaped cluster formations, dislocation loops.

X-ray diffraction characterization of MOVPE ZnSe films deposited on (100) GaAs using conventional and high-resolution diffractometers

ZnSe-based heterostructures grown on GaAs substrates have been investigated for use in pin-diode LED applications. In this study, a conventional Bragg-Brentano diffractometer (BBD) has been used to screen samples for phase identification, crystallite size, presence of polycrystalline ZnSe, and initial rocking curve (RC) analysis. A limitation of the conventional diffractometer is that the smallest RC full width at half maximum (FWHM) that can be achieved is 500 to 600 arc sec. As deposition parameters are optimized and the RC limit of the conventional diffractometer is reached, analysis is moved to a four-bounce high-resolution diffractometer (HRD). Although more time for analysis is required, using the HRD has a RC resolution advantage, where RCs of <20 arc sec are obtained for neat GaAs wafers. Combining the BBD and HRD instruments for analysis of ZnSe films grown on GaAs substrates allows for an efficient means of high sample throughput combined with an accurate measurement of film alignment.

Growth and optical properties of the Ce-doped Li 6Gd (BO 3) 3 crystal grown by the modified Bridgman method

The ternary oxide Li 6Gd(BO 3) 3:Ce crystals with dimensions up to Ø14 × 100 mm 3 were prepared by the modified Bridgman method. The crystallinity of crystal was measured using X-ray rocking curve analysis. The composition of the inclusions existing in the crystal was measured by electronic microprobe. The optical properties at room temperature were investigated by transmittance spectra and X-ray stimulated luminescence spectra (XSL).

High Quality Single Crystal 3C-SiC(111) Films Grown on Si(111)

We have developed a high-quality growth process for 3C-SiC on on-axis (111)Si substrates with the ultimate goal to demonstrate high quality and yield electronic and MEMS devices. A single-side polished 50 mm (111)Si wafer was loaded into a hot-wall SiC CVD reactor for growth. The 3C-SiC process was performed in two stages: carbonization in propane and hydrogen at 1135°C and 400 Torr followed by growth at 1380°C and 100 Torr. X-ray diffraction rocking curve analysis of the 3C-SiC(222) peak indicates a FWHM value of 219 arcsec. This is a very interesting result given that the film thickness was only 2 µm, thus indicating that the grown film is of very high quality compared with published literature values. X-ray polar figure mapping was performed and it was observed that the micro twin content was below the detection limit. Therefore TEM characterization was performed in plan view to allow assessment of the stacking fault density as well as confirmation of the very low micro twin concentration in this film. TEM analysis indicates a low concentration of stacking faults in the range of 104 cm-1.

Phase Transition of In/Si(111) Surface Studied by Reflection High-Energy Positron Diffraction

We determined the structures of Si(111)-4×1-In and Si(111)-8×2-In surfaces that are formed at 293 K and 60 K, respectively, through the rocking curve analyses of reflection high-energy positron diffraction (RHEPD). The structure of Si(111)-4×1-In surface is in good agreement with the zigzag chain structure determined by the surface X-ray diffraction [O. Bunk et al., Phys. Rev. B 59, 12228 (1999)]. In the Si(111)-8×2-In surface, In atoms are displaced in two dimensional directions from the positions of zigzag chain structure. The structure of Si(111)-8×2-In surface determined here is compatible to the hexagon structure predicted by the first principles study [C. Gonzalez, F. Flores, and J. Ortega, Phys. Rev. Lett. 96, 136101 (2006)]. We determined the surface Debye-temperatures of 4×1 and 8×2 phases to be 80 K and 130 K, respectively. [DOI: 10.1380/ejssnt.2009.436]

Correlation between Auger Intensity and Wave-Field Intensity for Si(001)2*2-Al Surface

According to dynamical theory of electron diffraction, the incident electron density distribution, or “wave-field”, was calculated for a parallel-dimer structure of Si(001)2×2-Al surface on the condition of medium-energy electron diffraction (MEED). The surface structure and the calculated method were confirmed to be effective by the rocking-curve analysis of diffracted beam intensity. The wave-field at the surface is very sensitive to changes in diffraction conditions, such as the incident glancing angle. The Al(LMM) Auger electron intensity emitted from the Si(001)2×2-Al surface during MEED incident beam rocking, that is named beam rocking Auger electron spectroscopy (BRAES), has been found to be correlated to the calculated wave-field intensity on the Al atomic rows. The BRAES profile of adsorbate Al(LMM) differs from that of substrate Si(LVV). [DOI: 10.1380/ejssnt.2009.97]

Effect of oxygen vacancies on ferroelectric behavior of Na 1/2Bi 1/2TiO 3–BaTiO 3 single crystals

One of the important lead-free ferroelectric solid solutions, sodium bismuth titanate–barium titanate Na 1/2Bi 1/2TiO 3–BaTiO 3 (NBT–BT) was grown by the conventional flux technique. In order to study the role of oxygen vacancies on the dielectric/ferroelectric properties, some of the crystal samples oriented along (0 0 1) and (1 0 0) planes were subjected to oxygen and nitrogen annealing processes to create different concentrations of oxygen vacancies in the samples. Dielectric and its loss measurements were carried out to analyze the role of oxygen vacancies and their corresponding dielectric behavior on NBT–BT crystals. Electron energy loss spectrum (EELS) has revealed that increasing oxygen vacancies has reduced oxidation states of Ti. X-ray rocking curve analysis has confirmed the degradation in the structural quality also on increasing the oxygen vacancies.

Growth defects in a PZNT93/7 crystal prepared by directional solidification

AbstractNovel relaxor ferroelectric crystal 0.93Pb(Zn1/3Nb2/3)O3‐0.07PbTiO3 (PZNT93/7) with dimensions about Ø40× 70 mm3 was obtained by directional solidification technique. The growth defects of the crystal were investigated. Rocking curve analysis revealed the crystalline quality of PZNT93/7 crystal was not perfect and the FWHM value was measured to be about 0.7°. Some pits and oxide particles in micro‐size were formed in the crystal due to the growth conditions. A series of growth steps parallel to (001) face were observed which were attributed to the growth behavior. Moreover, it was found the average chemical composition of the crystal was deviated slightly to the stoichiometric value of PZNT93/7. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Quality of KDP crystals grown on point seeds by a novel rapid growth method

Structural perfection of KDP single crystals grown on point seeds by a rapid growth method has been studied by selective etching, UV spectroscopy, x-ray topography, a conoscopic method (to assess anomalous birefringence), rocking-curve analysis, and resistivity measurements. Etching results indicate that the dipyramid growth sectors are less homogeneous. The zonal structure is more pronounced in the peripheral parts of the crystals, that is, in the final stages of rapid growth. In spite of the sectorial and zonal inhomogeneities, the crystals are superior in quality to those prepared by other rapid growth methods.

Synthesis, Growth, and Characterization of Novel Nonlinear Optical Active Dichloridodiglycine Zinc Dihydrate Single Crystals

The nonlinear optical photonic crystal of dichloridodiglycine zinc dihydrate was grown from a mixture of glycine and zinc chloride by a slow evaporation technique. The morphology and the structure of the grown crystal were characterized using single crystal X-ray diffraction analysis. The crystalline perfection of the grown crystal was analyzed using high-resolution X-ray diffractometry rocking curve analysis. Fourier transform infrared spectral analyses confirmed the presence of the functional groups in the crystal lattice. The second harmonic efficiency of the crystal was tested by the Kurtz powder technique. The optical property and thermal stability of the grown crystal were studied using UV absorption spectral and thermogravimetric/differential thermal analysis. Microhardness studies revealed that the hardness of the grown crystal increases with an increase in load. The presence of the elemental composition such as zinc and chlorine present in the title compound was confirmed by energy dispersive X-ray analysis.

Quasi-one-dimensional In atomic chains on Si(1 1 1) at low temperature studied by reflection high-energy positron diffraction and scanning tunneling microscopy

We have investigated a quasi-one-dimensional structure of Si(1 1 1)-8 × 2-In surface using reflection high-energy positron diffraction (RHEPD) and scanning tunneling microscopy (STM). From the RHEPD rocking curve analyses, we confirmed the formation of the In hexagon structure proposed by González et al. [C. González, F. Flores, J. Ortega, Phys. Rev. Lett. 96 (2006) 136101]. Furthermore, we found that the empty-state STM image at 44 K is consistent with that calculated with the optimum hexagon structure by the RHEPD analyses.

The influence of substrate polarity on the structural quality of InN layers grown by high-pressure chemical vapor deposition

The influence of substrate polarity on the properties of InN layers grown by high-pressure chemical vapor deposition has been studied. The 2Θ-ω x-ray diffraction scans on InN layers deposited on polar GaN epilayers revealed single-phase InN(0002) with a full width at half maximum (FWHM) of around 200arcsec. InN layers grown on N-polar GaN exhibit larger FWHMs. Rocking curve analysis confirmed single-phase InN for both growth polarities, with FWHM values for ω-RC(002) at 2080arcsec for InN grown on Ga-polar templates. The A1(LO) Raman mode analysis shows higher free carrier concentrations in InN grown on N-polar templates, indicating that polarity affects the incorporation of impurities.

Modification of local structures in multicrystals revealed by spatially resolved x-ray rocking curve analysis

We show that spatially resolved x-ray rocking curve analysis can be a useful technique to investigate local structures in bulk multicrystals and their modification during crystal growth when combined with appropriate samples. For this purpose, a model crystal growth experiment was carried out using a Si seed crystal with artificially controlled ⟨110⟩ tilted grain boundaries. The growth orientation was chosen as the scan axis for rocking curve measurements in different crystal grains. Thanks to the superior angle resolution, the gradual structural changes can be monitored by the changes in the rocking curve profile such as the peak shift and the peak splitting. The amount as well as the sign of the peak shift was found to be strongly dependent on the initial grain boundary structure. Furthermore, the technique was applied to investigate local structures of Si multicrystals with controlled grain orientation grown without any seeds.

Electron beam deposited VC and NbC thin films on titanium: Hardness and energy-dispersive X-ray diffraction study

Films of VC and NbC of about 200 nm thickness were electron beam deposited on the sandblasted surface of metallic Ti substrates, preheated at 350 and 500 °C, to improve the surface hardness of Ti implants intended for application in orthopaedics. According to both standard angular-dispersive X-ray diffraction measurements and rocking curve analysis performed by energy-dispersive X-ray diffraction, the films were found to be textured preferentially along the (200) crystallographic direction. The (200)-oriented crystallites are randomly rotated around their growth axes, with no correlation among adjacent domains. The measured intrinsic hardness of the films is 24–25 GPa for VC and 18–21 GPa for NbC.

Bi$_{3}$Fe$_{4}$Ga$_{1}$O$_{12}$ Garnet Properties and Its Application to Ultrafast Switching in the Visible Spectrum

We have synthesized Bi3Fe4Ga1O12 (BIGG) films on Gd3Ga5O12 and Gd3(ScGa)5O12 substrates by a pulsed laser deposition technique. X-ray diffraction and rocking curve analyses confirm the epitaxial quality of the films with a lattice constant close to 12.61 plusmn 0.01 Aring. Compared with that of a bismuth iron garnet Bi3Fe5O12 (BIG) film, the bandwidth of the BIGG transmittance (T) spectrum is extended and its left edge shifted down in wavelength by approximately 50 nm. This enables its Faraday rotation and switching speed to be tested at a wavelength of 532 nm. While BIGG film has a Faraday rotation angle slightly less than that of BIG film, its magnetooptical figure of merit, 2|thetasFd|/-ln(T%), is greatly improved to a typical value ~1.8 times larger than that of the BIG film. Further, the high-speed pulse response time of the BIGG film reaches 2.4 ns with a 1 mm aperture size at the wavelength of 532 nm.

Carbon Thin Films from Plant‐Derived Precursors

Thin films of nanocrystalline diamond‐like carbon thin film are synthesized by the thermal flash vapor deposition technique using turpentine oil. Effect of applied voltage and substrate temperature on the formation of thin film of carbon is discussed. It is observed that at substrate temperature (750°C), semiconducting Nanocrystalline diamond‐like carbon thin films with prominent (111) phase and band gap 1.04 eV can be prepared by flash evaporation techniques in less than 3 minutes. XRD, Rocking Curve analysis, SEM and Raman studies were carried out to confirm the structure of film prepared by this method. Electrical conductivity and optical band gap analysis were done to find out the electrical properties and band gap of the film.