外延结晶与材料相变过程中原位硬X射线纳米束表征装置

Avalanche effects in solid-phase epitaxial crystallization induced by light-ion irradiation

Solid-phase epitaxial crystallization of amorphous Si layers on a crystalline Si substrate during B-ion irradiation is investigated over the temperature range 293 - 573 K. Regrowth occurs at all measured temperatures, with activation energy 0.07 eV and prefactor 2.36 nm / 10^14 B cm-2 The low activation energy suggests that free interstitial point defects are involved and the unusually large prefactor indicates that each interstitial crystallizes about 50 host Si atoms. We propose that interstitial annihilation at the a/c interface sets off a shock-like process that drives c-Si island nucleati…

Dynamical Scattering in Coherent Hard X-Ray Nanobeam Bragg Diffraction

Unique intensity features arising from dynamical diffraction arise in coherent x-ray nanobeam diffraction patterns of crystals having thicknesses larger than the x-ray extinction depth or exhibiting combinations of nanoscale and mesoscale features. We demonstrate that dynamical scattering effects can be accurately predicted using an optical model combined with the Darwin theory of dynamical x-ray diffraction. The model includes the highly divergent coherent x-ray nanobeams produced by Fresnel zone plate focusing optics and accounts for primary extinction, multiple scattering, and absorption. T…

Solid phase epitaxial growth of the correlated-electron transparent conducting oxide SrVO3

SrVO3 thin films with a high figure of merit for applications as transparent conductors were crystallized from amorphous layers using solid phase epitaxy (SPE). Epitaxial SrVO3 films crystallized on SrTiO3 using SPE exhibit a room temperature resistivity of 2.5 x 10-5 Ohms cm, a residual resistivity ratio of 3.8, and visible light transmission above 0.5 for a 60 nm-thick film. SrVO3 layers were deposited at room temperature using radio-frequency sputtering in an amorphous form and subsequently crystallized by heating in controlled gas environment. The lattice parameters and mosaic angular widt…

Crystallization of heavy fermions via epitaxial strain in spinel LiV$_{2}$O$_{4}$ thin film

The mixed-valent spinel LiV$_{2}$O$_{4}$ is known as the first oxide heavy-fermion system. There is a general consensus that a subtle interplay of charge, spin, and orbital degrees of freedom of correlated electrons plays a crucial role in the enhancement of quasi-particle mass, but the specific mechanism has remained yet elusive. A charge-ordering (CO) instability of V$^{3+}$ and V$^{4+}$ ions that is geometrically frustrated by the V pyrochlore sublattice from forming a long-range CO down to $T$ = 0 K has been proposed as a prime candidate for the mechanism. To uncover the hidden CO instabil…

通过原位纳米束X射线衍射研究非常规铁电$Hf_{0.5}Zr_{0.5}O_{2}$基电容器的机电行为

Investigating the Electromechanical Behavior of Unconventionally Ferroelectric $Hf_{0.5}Zr_{0.5}O_{2}$-based Capacitors Through Operando Nanobeam X-ray Diffraction

本研究通过原位纳米束X射线衍射实验，探究了外延HfZrO基铁电电容器的非常规弱机电响应，发现其菱方相具有负压电效应，且响应在矫顽电压以上被抑制，凸显了极化切换的独特性质。

Formation of Nanotwin Networks during High-Temperature Crystallization of Amorphous Germanium

Germanium is an extremely important material used for numerous functional applications in many fields of nanotechnology. In this paper, we study the crystallization of amorphous Ge using atomistic simulations of critical nano-metric nuclei at high temperatures. We find that crystallization occurs by the recurrent transfer of atoms via a diffusive process from the amorphous phase into suitably-oriented crystalline layers. We accompany our simulations with a comprehensive thermodynamic and kinetic analysis of the growth process, which explains the energy balance and the interfacial growth veloci…