Single crystal

About: Single crystal is a research topic. Over the lifetime, 59617 publications have been published within this topic receiving 870828 citations.

Method of growing GaN crystal, method of producing single crystal GaN substrate, and single crystal GaN substrate

Abstract: A low dislocation density GaN single crystal substrate is made by forming a seed mask having parallel stripes regularly and periodically aligning on an undersubstrate, growing a GaN crystal on a facet-growth condition, forming repetitions of parallel facet hills and facet valleys rooted upon the mask stripes, maintaining the facet hills and facet valleys, producing voluminous defect accumulating regions (H) accompanying the valleys, yielding low dislocation single crystal regions (Z) following the facets, making C-plane growth regions (Y) following flat tops between the facets, gathering dislocations on the facets into the valleys by the action of the growing facets, reducing dislocations in the low dislocation single crystal regions (Z) and the C-plane growth regions (Y), and accumulating the dislocations in cores (S) or interfaces (K) of the voluminous defect accumulating regions (H).

Structural, optical, and electrical properties of epitaxial chalcopyrite CuIn3Se5 films

Abstract: Single crystal CuIn3Se5 epitaxial films have been synthesized on GaAs(001) by a hybrid sputtering and evaporation technique The microstructure, microchemistry, and selected electrical and optical properties of the films have been investigated by scanning electron microscopy, energy dispersive x‐ray spectroscopy, transmission electron microscopy, cathodoluminescence, optical absorption and reflection, and four‐point probe resistivity measurements The results showed that the CuIn3Se5 crystals have an ordered point defect structure, a band gap of ≥118 eV, an optical absorption coefficient of about 15 000 cm−1 at a photon energy of 135 eV, and a film resistivity of ≳105 Ω cm The results suggest the presence of band tails giving rise to subgap radiative recombination and absorption Antiphase domain boundaries, stacking faults, and nanotwins were observed in the epitaxial layers and were reduced in number by rapid thermal annealing

A systematic study of OH in hydrous wadsleyite from polarized FTIR spectroscopy and single-crystal X-ray diffraction: Oxygen sites for hydrogen storage in Earth∑ s interior

Abstract: The incorporation of hydrogen into wadsleyite (β-Mg 2 SiO 4 ) was investigated using poltarized FTIR spectroscopy and X-ray diffraction on oriented single crystals. The experiments were carried out with a new suite of samples containing between ~100 and ~10 000 ppm H 2 O by weight (wt ppm), encompassing the H-contents most relevant to Earth’s potentially hydrous mantle transition zone. Attempts to synthesize anhydrous wadsleyite resulted in water contents of no less than ~50 wt ppm H 2 O. An empirical relation between the b / a axial ratio against estimated wt ppm concentrations of H 2 O in wadsleyite ( C H 2 O ) was determined: ( b / a ) = 2.008(1) + 1.25(3) × 10 −6 · C H 2 O Polarized infrared absorption spectra were measured in the three orthogonal sections perpendicular to the major axes of the optical indicatrix ellipsoid and are used in concert with results from new structure refinements to place constraints on the main absorbers in the structure. All of the main bands in the O-H stretching region of the FTIR can be explained by protonation of O1, the anomalous non-silicate oxygen site. We assign the band at 3614 cm −1 to a bent hydrogen bond O1···O1 (2.887 A) along the M3 edge in the a-c plane. The band at 3581 cm −1 is assigned to a bent hydrogen bond on O1···O3 (3.016 A) of the M3 edge in the b-c plane. The absorption bands at 3360, 3326, and 3317 cm −1 are best explained by hydrogen bonds on O1···O4 (3.092 A) and O1···O4 (2.795 A) along the M3 and M2 edges with possible splitting of one band due to vacancy ordering, but we cannot rule out contributions from three other (O1···O3) edges. The broad absorption feature at 3000 cm −1 is unambiguously assigned to the O4···O4 (2.720 A) tetrahedral edge of the Si 2 O 7 group pointing along the [100] vector. On hydration to ~1 wt% H 2 O, M-site vacancies are observed exclusively at M3. A systematic shortening of several (interpreted) hydrogen bonded O···O M-site edges is attributed to reduced O-O repulsive forces on protonation in the vicinity of an M-site vacancy.

Flux growth of some complex oxide materials

Abstract: This paper describes the preparation of the following complex oxide crystals which have not previously been grown by the flux method: FeNbO4, MnWO4, CoWO4, NiWO4, RMn2O5 (R = Er to Sm, and Y), RMnO3 (R = Er to Gd), LaOCl, La2Ti2O71, Bi2Sn2O7, and PbTiP2O8. Single crystal X-ray diffraction data are reported for the latter material, the preparation of which has not previously been reported, and for La2Ti2O7 and Bi2Sn2O71, for which only powder data were previously available. Improved methods for the growth of Mn3O4, LaCoO3, RPO4 (R = Yb to Gd), RCrO3 (R = Lu, Yb), ErOF and NaNbO3 are also reported.