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10 Jul 2006

Volume 89, Issue 2, Articles (02xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 89, 023901 (2006); http://dx.doi.org/10.1063/1.2219984 (3 pages)

Nikhil Ganesh, Ian D. Block, and Brian T. Cunningham
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Optical phonon decay in bulk aluminum nitride

D. Y. Song, M. Holtz, A. Chandolu, S. A. Nikishin, E. N. Mokhov, Yu. Makarov, and H. Helava

Appl. Phys. Lett. 89, 021901 (2006); http://dx.doi.org/10.1063/1.2219092 (3 pages) | Cited 8 times

Online Publication Date: 10 July 2006

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We report Raman studies of the E22 and A1(LO) symmetry phonons of bulk AlN from 13 to 375 K. Based on observed dependences of the phonon energies and linewidths, and accounting for the temperature-dependent thermal expansion, we determine that both phonon lifetimes are limited by two-phonon decay. The E22 decays symmetrically. The A1(LO) asymmetrically decays into vibrations with energies 586 and 309 cm−1 which we attribute to A1(TO) and LA phonons from the M point of the Brillouin zone.
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63.20.-e Phonons in crystal lattices
78.20.-e Optical properties of bulk materials and thin films
78.30.Fs III-V and II-VI semiconductors
65.40.De Thermal expansion; thermomechanical effects

Local electron beam induced reduction and crystallization of amorphous titania films

Philippe Kern, Christian Jäggi, Ivo Utke, Vinzenz Friedli, and Johann Michler

Appl. Phys. Lett. 89, 021902 (2006); http://dx.doi.org/10.1063/1.2219398 (3 pages) | Cited 9 times

Online Publication Date: 10 July 2006

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We report local electron beam induced reduction and crystallization of electrolytic amorphous TiO2 films on steel at 20 keV, varying beam currents from 10 nA to 24 μA. In situ substrate temperature measurements and beam heating calculations demonstrate the formation of anatase (Raman) below 270 °C, clearly beneath the crystallization temperature of nonirradiated films (≈440 °C). The evolution of the sample current was correlated to oxide reduction via electron stimulated desorption. Atomic force microscopy revealed well defined cavities with Gaussian shape. The e-beam sensitivity of amorphous TiO2 allows for patterning of macroscopic films, inducing local changes in oxidation state and phase.
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82.30.-b Specific chemical reactions; reaction mechanisms
64.70.K- Solid-solid transitions
61.80.Fe Electron and positron radiation effects
61.82.Fk Semiconductors
78.66.Jg Amorphous semiconductors; glasses
68.43.Rs Electron stimulated desorption

Direct evidence of N aggregation and diffusion in Au+ irradiated GaN

W. Jiang, Y. Zhang, W. J. Weber, J. Lian, and R. C. Ewing

Appl. Phys. Lett. 89, 021903 (2006); http://dx.doi.org/10.1063/1.2219418 (3 pages) | Cited 21 times

Online Publication Date: 10 July 2006

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A surface amorphized layer and a buried disordered structure were created in gallium nitride (GaN) irradiated using 1.0 MeV Au+ ions to fluences of 25 and 70 Au+/nm2 at room temperature. Bubbles of N2 gas within both the amorphized and disordered GaN are formed. A gradient profile with a lower N concentration in the amorphized region is observed, which provides direct evidence of N loss by diffusion in the Au+ irradiated GaN. These results are important to understanding the amorphization processes in GaN and may have significant implications for the design and fabrication of GaN-based devices.
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66.30.J- Diffusion of impurities
61.43.Dq Amorphous semiconductors, metals, and alloys
61.82.Fk Semiconductors
61.72.Qq Microscopic defects (voids, inclusions, etc.)

Phase transition process in oxide-ion conductor β-La2Mo2−xWxO9 assessed by internal friction method

X. P. Wang, D. Li, Q. F. Fang, Z. J. Cheng, G. Corbel, and P. Lacorre

Appl. Phys. Lett. 89, 021904 (2006); http://dx.doi.org/10.1063/1.2220056 (3 pages) | Cited 14 times

Online Publication Date: 11 July 2006

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The oxygen ion diffusion and phase transition in La2Mo2−xWxO9 (x = 0, 0.25, 0.75, 1.0, and 1.4) have been investigated by the internal friction method. In addition to the low-temperature relaxation peak associated with oxygen ion diffusion, an internal friction peak of phase transition type is observed around 350 °C in all tungsten substituted La2Mo2O9 compounds. Based on the behavior of this peak and the ionic conduction properties, the mechanism of this peak is suggested to be associated with a transition from static disordered state to dynamic disordered state of oxygen ion distribution in anion sublattice that most probably results in a transition of the ionic conduction from the Arrhenius type to the Vogel-Tamman-Fulcher type.
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64.70.K- Solid-solid transitions
66.30.H- Self-diffusion and ionic conduction in nonmetals
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances

Backward beam fanning in organic photorefractive devices

O-Pil Kwon, Mojca Jazbinsek, Peter Günter, and Suck-Hyun Lee

Appl. Phys. Lett. 89, 021905 (2006); http://dx.doi.org/10.1063/1.2219979 (3 pages) | Cited 2 times

Online Publication Date: 11 July 2006

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We observe strong beam depletion of about 30% at small incident angles in layered photorefractive polymers at an electric field of −50 V/μm and an intensity of 0.3 W/cm2. At normal incidence this depletion occurs only with negative electric field directions. For positive fields, depletion occurs only in the tilted geometry and is due to forward beam fanning, as previously observed. We attribute the depletion for negative electric fields mainly to the backward beam fanning as a consequence of the relatively high beam coupling efficiency in reflection grating geometries.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.70.Jk Polymers and organics
42.79.Dj Gratings

Passive low pass filtering effect of mechanical vibrations by a granular bed composed of microglass beads

Sang-Hee Yoon and Ki Lyug Kim

Appl. Phys. Lett. 89, 021906 (2006); http://dx.doi.org/10.1063/1.2220012 (3 pages) | Cited 3 times

Online Publication Date: 11 July 2006

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Passive low pass filtering characteristics of a granular bed composed of microglass beads (MGBs) are investigated for military applications to a shock isolator. The granular bed attenuates the transmission of vibrations over a given frequency range sensitive to electronic devices through kinetic energy absorption like low pass filters in electric system. The experimental studies on five kinds of MGB with different diameters demonstrate that the cutoff frequency and the steepness of rolloff of the granular bed are inversely proportional to the diameter of MGB, and the vibration absorptivity is proportional to the diameter of MGB. The granular bed composed of 68 μm diameter MGB absorbs incident mechanical vibrations with the cutoff frequency of 16.0±1.5 kHz, the vibration absorptivity of 0.22, and the stopband transmittance of 1%–10%.
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84.30.Vn Filters

Photoluminescence study of InSb/AlxIn1−xSb quantum wells

X. H. Zhang, R. E. Doezema, N. Goel, S. J. Chung, M. B. Santos, N. Dai, F. H. Zhao, and Z. S. Shi

Appl. Phys. Lett. 89, 021907 (2006); http://dx.doi.org/10.1063/1.2220535 (3 pages) | Cited 1 time

Online Publication Date: 11 July 2006

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We present the results of photoluminescence experiments on InSb/AlxIn1−xSb multi-quantum-wells on GaAs substrates. A comparison of the photoluminescence signals with transmission measurements shows Stokes shifts of 2.8–6.9 meV, indicating that the low temperature luminescence is mainly due to bound excitons localized by interfacial potential minima. The high temperature signal is attributed to ionized free carriers. The well width dependent thermal activation energy investigation indicates that nonradiative carrier loss from the wells to the barriers is not a dominant mechanism. Instead, we suggest that the thermal recombination by surface dislocations or defects might be the main nonradiative channel for high temperature luminescence.
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78.67.De Quantum wells
78.55.Cr III-V semiconductors
73.21.Fg Quantum wells
68.65.Fg Quantum wells
71.35.-y Excitons and related phenomena
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Visualization of the complex refractive index of a conductor by frustrated total internal reflection

Yu. P. Bliokh, R. Vander, S. G. Lipson, and J. Felsteiner

Appl. Phys. Lett. 89, 021908 (2006); http://dx.doi.org/10.1063/1.2220540 (3 pages) | Cited 3 times

Online Publication Date: 11 July 2006

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A simple imaging geometry in which total internal reflection in a glass prism is frustrated by the proximity of a metal surface is implemented for observation of surface plasmon resonance. At a certain angle of incidence, the total internal reflection is completely suppressed at a certain distance between the metal and the prism surfaces. Using planar metal and spherical prism surfaces, the distance parameter is sampled in a single image. This allows a direct determination of the complex refractive index in bulk samples as well as in thin films. Our experimental data are in good agreement with previously published data.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
42.79.Bh Lenses, prisms and mirrors

Near-infrared scintillation of xenon by math beta decay

Norimasa Yoshimizu, Amit Lal, and Clifford R. Pollock

Appl. Phys. Lett. 89, 021909 (2006); http://dx.doi.org/10.1063/1.2218063 (3 pages)

Online Publication Date: 11 July 2006

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The near-infrared scintillation of xenon gas by the β decay of 37 MBq of math was studied, in the interest of its use in integrated devices for applications such as optical beacons and wavelength calibration. The emission was imaged and analyzed using Spencer’s theory of electron penetration using xenon scattering cross sections derived from Thomas-Fermi theory. The total emission was approximately 2×105 photons/s at 20 kPa and 1×105 photons/s at 100 kPa. Spectral data show three dominant peaks at 823, 828, and 882 nm as well as the formation of metastable states.
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51.70.+f Optical and dielectric properties
06.20.fb Standards and calibration

Controlled blueshift of the resonant wavelength in porous silicon microcavities using ion irradiation

D. Mangaiyarkarasi, M. B. H. Breese, Y. S. Ow, and C. Vijila

Appl. Phys. Lett. 89, 021910 (2006); http://dx.doi.org/10.1063/1.2219989 (3 pages) | Cited 7 times

Online Publication Date: 12 July 2006

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High-energy focused proton beam irradiation has been used to controllably blueshift the resonant wavelength of porous silicon microcavities in heavily doped p-type wafers. Irradiation results in an increased resistivity, hence a locally reduced rate of anodization. Irradiated regions are consequently thinner and of a higher refractive index than unirradiated regions, and the microcavity blueshift arises from a net reduction in the optical thickness of each porous layer. Using this process wafers are patterned on a micrometer lateral scale with microcavities tuned to different resonant wavelengths, giving rise to high-resolution full-color reflection images over the full visible spectrum.
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61.82.Fk Semiconductors
61.80.Jh Ion radiation effects
81.65.Cf Surface cleaning, etching, patterning
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.40.Fy Semiconductors
82.45.-h Electrochemistry and electrophoresis

Mapping substrate/film adhesion with contact-resonance-frequency atomic force microscopy

D. C. Hurley, M. Kopycinska-Müller, E. D. Langlois, A. B. Kos, and N. Barbosa

Appl. Phys. Lett. 89, 021911 (2006); http://dx.doi.org/10.1063/1.2221404 (3 pages) | Cited 9 times

Online Publication Date: 12 July 2006

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We have used contact-resonance-frequency atomic force microscopy techniques to nondestructively image variations in adhesion at a buried interface. Images were acquired on a sample containing a 20 nm gold (Au) blanket film on silicon (Si) with a 1 nm patterned interlayer of titanium (Ti). This design produced regions of very weak adhesion (Si/Au) and regions of strong adhesion (Si/Ti/Au). Values of the contact stiffness were 5% lower in the regions of weak adhesion. The observed behavior is consistent with theoretical predictions for layered systems with disbonds. Our results represent progress towards quantitative measurement of adhesion parameters on the nanoscale.
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68.35.Ct Interface structure and roughness
68.37.Ps Atomic force microscopy (AFM)
68.35.Np Adhesion
68.35.Gy Mechanical properties; surface strains
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity

Anomalous temperature dependence of absorption edge in narrow-gap HgCdTe semiconductors

Fangyu Yue, Jun Shao, Xiang Lü, Wei Huang, Junhao Chu, Jun Wu, Xingchao Lin, and Li He

Appl. Phys. Lett. 89, 021912 (2006); http://dx.doi.org/10.1063/1.2221411 (3 pages) | Cited 16 times

Online Publication Date: 12 July 2006

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Abnormal temperature dependence of absorption edge is reported for narrow-gap Hg1−xCdxTe semiconductors at low temperature. Infrared absorption spectra are taken for bulk and molecular-beam epitaxial Hg1−xCdxTe, respectively, in the temperature range of 11–300 K. The results indicate an abnormal shift of the absorption edge around the temperature range of 30–70 K. Analysis suggests that (i) the phenomenon is introduced by Hg vacancies in the samples, of which the energy level locates about 9–12 meV above the Hg1−xCdxTe valence band, and (ii) the conventional criterion for the determination of band gap energy, Eg, from absorption spectra is not accurate enough as soon as Hg vacancies exist, especially at a temperature above 77 K. It hence provides an explanation why there should exist difference between the cutoff wavelength of the detector and the absorption-edge (Eg) wavelength of the material the detector was made of.
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78.66.Hf II-VI semiconductors
78.30.Fs III-V and II-VI semiconductors
71.20.Nr Semiconductor compounds
61.72.J- Point defects and defect clusters

Stabilized switchable “black state” in Mg2NiH4/Ti/Pd thin films for optical hydrogen sensing

M. Pasturel, M. Slaman, D. M. Borsa, H. Schreuders, B. Dam, R. Griessen, W. Lohstroh, and A. Borgschulte

Appl. Phys. Lett. 89, 021913 (2006); http://dx.doi.org/10.1063/1.2221412 (3 pages) | Cited 11 times

Online Publication Date: 12 July 2006

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A triple layer thin film (30 nm Mg2Ni/100 nm Ti/10 nm Pd sputtered on glass) switches reversibly from a shiny metallic to a “black” state upon exposure to moderate hydrogen pressure ( ≈ 5.103 Pa). This black state resembles that obtained in thick Mg2NiHx layers and has the great advantage of being stable and easily controlled. Both the reversible high optical contrast (Rreflective/Rblack ≈ 10 in the red wavelength range) and the fast kinetics of hydrogen absorption and desorption make this material interesting for applications as optical hydrogen sensors.
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78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
68.43.Mn Adsorption kinetics
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing

Phase change observation in reflection multilayers by total electron yield and reflection spectra

Takeo Ejima, Tetsuo Harada, and Atsushi Yamazaki

Appl. Phys. Lett. 89, 021914 (2006); http://dx.doi.org/10.1063/1.2220061 (3 pages) | Cited 1 time

Online Publication Date: 13 July 2006

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Precise optical elements for use in the extreme ultraviolet region are necessary for controlling both the uppermost layer thickness and the reflection phase in a reflection multilayer system. In this study, a phase value corresponding to both the uppermost layer thickness and the reflection phase was derived from the reflectance and total electron yield (TEY) intensity. Mo/Si multilayers were fabricated on a silicon wafer with various thicknesses of the uppermost Mo layer. Phase values obtained from the reflection and TEY measurements were found to change in accordance with increases in the thickness of the uppermost Mo layer and a concomitant change in the reflection phase.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
42.70.-a Optical materials
42.79.Wc Optical coatings
78.40.Fy Semiconductors
78.40.Kc Metals, semimetals, and alloys

Intense photoluminescence from amorphous tantalum oxide films

Minmin Zhu, Zhengjun Zhang, and Wei Miao

Appl. Phys. Lett. 89, 021915 (2006); http://dx.doi.org/10.1063/1.2219991 (3 pages) | Cited 21 times

Online Publication Date: 13 July 2006

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Tantalum oxide films were deposited on silicon substrates at a temperature of ∼ 450 °C by heating a pure tantalum foil in a rough vacuum. The films were amorphous in structure and consisted of fully oxidized Ta2O5 and (TaOx, x<2.5) suboxides. This feature resulted in strong visible light emission from the films further oxidized in the air at temperatures of 200–300 °C. The mechanism for this photoluminescence behavior of the amorphous tantalum oxide films was also investigated and discussed. This study suggests that wide-band-gap materials could act as effective visible light emitters and provides a simple route to synthesize such materials.
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77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
78.66.Nk Insulators
78.55.Hx Other solid inorganic materials
81.40.Gh Other heat and thermomechanical treatments
68.55.-a Thin film structure and morphology

Impact of 4H– and 6H–SiC(0001) nitridation on Ga wetting layer development and GaN growth by molecular beam epitaxy

Tong-Ho Kim, Soojeong Choi, April S. Brown, Maria Losurdo, and Giovanni Bruno

Appl. Phys. Lett. 89, 021916 (2006); http://dx.doi.org/10.1063/1.2220007 (3 pages) | Cited 3 times

Online Publication Date: 13 July 2006

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GaN epitaxial layers have been grown by plasma-assisted molecular beam epitaxy on Si-face 4H– and 6H–SiC(0001)Si substrates. The impact of the SiC surface preparation and oxide removal achieved via a Ga flash-off process followed by nitridation on the structure and properties of GaN epitaxial layers is articulated. A correlation among the SiC surface nitridation conditions, the Ga wetting layer development, the nucleation layer, and GaN crystalline properties is revealed.
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81.05.Ea III-V semiconductors
81.65.Lp Surface hardening: nitridation, carburization, carbonitridation
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
52.77.-j Plasma applications
68.55.A- Nucleation and growth

First-principles prediction of low shear-strain resistance of Al3BC3: A metal borocarbide containing short linear BC2 units

Jingyang Wang, Yanchun Zhou, Ting Liao, and Zhijun Lin

Appl. Phys. Lett. 89, 021917 (2006); http://dx.doi.org/10.1063/1.2220549 (3 pages) | Cited 30 times

Online Publication Date: 13 July 2006

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The elastic stiffness and shear deformation mode of Al3BC3, a metal borocarbide containing linear C–B–C units, are studied based on the first-principles total energy calculations. The predominant effect of C–B–C units on mechanical properties is reported by leading to low shear modulus. The low shear-strain resistance originates from the deformation mode as follows: the rigid linear C–B–C units tilt with respect to the c direction easily, and the corner-sharing Al5C bipyramid slabs simultaneously slide along the basal plane with low resistance. The proposed deformation mode may be universal for the ternary metal borocarbides family containing short linear C–B–C units.
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81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity
71.15.Nc Total energy and cohesive energy calculations

Strongly enhanced nitriding kinetics by means of grain refinement

W. P. Tong, C. S. He, J. C. He, L. Zuo, N. R. Tao, and Z. B. Wang

Appl. Phys. Lett. 89, 021918 (2006); http://dx.doi.org/10.1063/1.2221498 (3 pages) | Cited 7 times

Online Publication Date: 13 July 2006

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By means of surface mechanical attrition treatment (SMAT), a nanostructured surface layer was formed on a pure Fe plate. Low-temperature gaseous nitriding of the SMAT Fe sample was investigated in comparison with the coarse-grained sample. It was found that the nitriding kinetics of nanostructured α-Fe was obviously enhanced, and the temperature to form nitrides from the nanostructured α-Fe was greatly reduced with respect to that of the coarse-grained form. The effective activation energy for diffusion of nitrogen in nanocrystalline nitride layer was calculated from the temperature dependence of compound layer thickness, the obtained value being about 54.39 kJ/mol, evidently smaller than that for coarse-grained ε phase (80.7 kJ/mol) and γ′ phase (88.3 kJ/mol).
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81.07.Bc Nanocrystalline materials
81.65.Lp Surface hardening: nitridation, carburization, carbonitridation
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
66.30.J- Diffusion of impurities
61.46.Hk Nanocrystals

Coarse-grained model for a molecular crystal

Richard H. Gee, Christine Wu, and Amitesh Maiti

Appl. Phys. Lett. 89, 021919 (2006); http://dx.doi.org/10.1063/1.2221878 (3 pages) | Cited 5 times

Online Publication Date: 14 July 2006

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Using the energetic material pentaerythritol tetranitrate as a specific example of molecular crystal, we describe the development of a simple coarse-graining procedure by grouping several atoms or whole functional groups into single charge-neutral beads. As compared to fully atomistic calculations the coarse-grained model speeds up simulations by more than two orders of magnitude. Yet, by adjusting only two parameters in the coarse-grained interaction, the model accurately predicts the lattice constants, sublimation energy, pressure-volume curve up to P = 10 GPa, and energetically the most stable facets. Computed surface and desorption energies, bulk modulus, and equilibrium morphology are reported as well.
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61.66.Hq Organic compounds
68.35.Md Surface thermodynamics, surface energies
68.43.Mn Adsorption kinetics
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity

Experimental studies on intermediate compound of LiBH4

Shin-Ichi Orimo, Yuko Nakamori, Nobuko Ohba, Kazutoshi Miwa, Masakazu Aoki, Shin-ichi Towata, and Andreas Züttel

Appl. Phys. Lett. 89, 021920 (2006); http://dx.doi.org/10.1063/1.2221880 (3 pages) | Cited 77 times

Online Publication Date: 14 July 2006

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The formation condition of an intermediate compound of LiBH4 during the partial dehydriding reaction and its local atomistic structure have been experimentally investigated. LiBH4 changes into an intermediate compound accompanying the release of approximately 11 mass % of hydrogen at 700–730 K. The Raman spectra indicate that the B–H bending and stretching modes of the compound appear at lower and higher frequencies, respectively, as compared to those of LiBH4. These features are consistent with the theoretical calculation on the monoclinic Li2B12H12, consisting of Li+ and [B12H12]2− ions, as a possible intermediate compound of LiBH4.
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78.30.Hv Other nonmetallic inorganics
61.66.Fn Inorganic compounds

Synthesis of bulk metallic glass foam by powder extrusion with a fugitive second phase

Min Ha Lee and Daniel J. Sordelet

Appl. Phys. Lett. 89, 021921 (2006); http://dx.doi.org/10.1063/1.2221882 (3 pages) | Cited 15 times

Online Publication Date: 14 July 2006

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Bulk metallic glass foams with 12 mm in diameter and 30 mm in length having a density of 4.62 g/cm3 (approximately 58.3% of theoretical) were fabricated by extruding a powder mixture comprised of 60 vol % Ni59Zr20Ti16Si2Sn3 metallic glass blended with 40 vol % brass followed by dissolution of the fugitive brass in an aqueous HNO3 solution. The final structure consists of continuously connected, high aspect ratio metallic glass struts surrounded by ∼ 40 vol % of homogeneously distributed ellipsoid-shaped pores having nominal diameters between 10 and 50 μm.
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81.05.Kf Glasses (including metallic glasses)
81.05.Bx Metals, semimetals, and alloys
81.05.Rm Porous materials; granular materials
82.70.Rr Aerosols and foams
61.43.Fs Glasses
61.43.Gt Powders, porous materials

X-ray diffraction peaks at glancing incidence and glancing exit from highly mismatched epitaxial layers

V. M. Kaganer, A. Shalimov, J. Bak-Misiuk, and K. H. Ploog

Appl. Phys. Lett. 89, 021922 (2006); http://dx.doi.org/10.1063/1.2221885 (3 pages) | Cited 5 times

Online Publication Date: 14 July 2006

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We find that the widths of double-crystal x-ray diffraction peaks in asymmetric reflections of relaxed GaAs/Si(001) heteroepitaxial layers in reciprocal diffraction geometries (glancing incidence and glancing exit) are notably different. This observation is in agreement with previous measurements on other heteroepitaxial systems but apparently contradicts the reciprocity principle of electrodynamics. We show that the apparent contradiction originates from the summation of the scattered waves that are collected by the detector in a double-crystal setup and resolve it by giving an appropriate description of the peak widths.
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61.05.cp X-ray diffraction
61.05.cf X-ray scattering (including small-angle scattering)
78.70.Ck X-ray scattering
68.60.Bs Mechanical and acoustical properties
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