Simulation of anisotropic wet-chemical etching using a physical model

We present a method to describe the orientation dependence of the etch rate of silicon, or any other single crystalline material, in anisotropic etching solutions by analytical functions. The parameters in these functions have a simple physical meaning. Crystals have a small number of atomically smooth faces, which etch (and grow) slowly as a consequence of the removal (or addition) of atoms by rows and layers. However, smooth faces have a roughening transition (well known in statistical physics); at increasing temperature they become rougher, and accordingly the etch and growth rates increase. Consequently, the basic physical parameters of our functions are the roughness of the smooth faces and the velocity of steps on these faces. This small set of parameters describes the etch rate in the two-dimensional space of orientations (on the unit sphere). We have applied our method to the practical case of etch rate functions for silicon crystals in KOH solutions. The maximum deviation between experimental data and simulation using only nine physically meaningful parameters is less than 5% of the maximum etch rate. This method, which in this study is used to describe anisotropic etching of silicon, can easily be adjusted to describe the growth or etching process of any crysta

On the concomitant crystallization of amino acid crystals upon dissolution of some amino acid salt crystals

Contains fulltext : 140110.pdf (publisher's version ) (Open Access

Interlacing of growth steps on crystal surfaces as a consequence of crystallographic symmetry.

Contains fulltext : 60551.pdf (publisher's version ) (Closed access)During crystal growth, concentric steps of unit-layer thickness [= dhklu with the surface's hkl Miller indices corrected according to the selection rules for non-primitive lattices] are often found to split into lower steps in a regular fashion [Frank (1951). Phil. Mag. 42, 1014-1021]. These 'interlaced' step patterns are introduced by a stacking of two or more growth layers, with different lateral anisotropy in step velocity within each unit layer. In this paper, a general relation between the symmetry of the crystal surface and the configuration of the concentric step patterns thereon is derived and is used to give theoretical shapes of spirals, growth hillocks and etch pits. It is shown that many of the interlaced patterns and their details are imposed by the presence of screw axes and/or glide planes perpendicular to the crystal surface. Finally, the results are compared with the patterns of unit-layer height and lower steps observed by optical and atomic force microscopy on crystals such as SiC, GaN, potash alum, garnet and NiSO4*6H2O

Verification of crystal growth models by detailed surface microtopography and X-ray diffraction topography

Contains fulltext : mmubn000001_027001466.pdf (publisher's version ) (Open Access)Promotores : P. Bennema en J. Bloem cum laude408 p

4,6 miljard jaar oude opalen in meteoriet

Item does not contain fulltex

Growth of Crystal Faces Enhanced by 3D Nuclei Deposition: A Monte Carlo Simulation

Item does not contain fulltextIn general, crystal growth proceeds by the addition of growth units at steps originating from dislocations or 2D nuclei. However, evidence exists that small 3D nuclei deposited on crystal faces can also act as step sources. In this study, the Monte Carlo method, based on the Kossel model, is used to study the fates of 3D nuclei adsorbed on planar and stepped crystal surfaces. For equilibrium, Delta mu/kT = 0, the nuclei dissolve completely, regardless of size. For supersaturated solutions, Delta mu/kT > 0, the upper parts of the nuclei dissolve, while the lower parts act as a source of steps expanding over the surface. This results in flat topped growth islands, the slope of which side faces increases for increasing nucleus size and supersaturation and decreasing bond strength. Growth on stepped surfaces leads to the formation of approximately circular plateaus, the width of which increases with decreasing substrate slope. Upon continued growth, these plateaus evolve into bunched step patterns. The Monte Carlo simulations are supplemented with a semiquantitative model, which helps in explaining the features observed by the Monte Carlo method

Crystal growth in a three-phase system: Diffusion and liquid-liquid phase separation in lysozyme crystal growth

Contains fulltext : 34959.pdf (publisher's version ) (Open Access

Orientation dependent surface stabilization on flame deposited diamond single crystals

Contains fulltext : 28129.pdf (publisher's version ) (Open Access

"Tailor-made" inhibitors in crystal growth: a Monte Carlo simulation study

Contains fulltext : 72755.pdf (publisher's version ) (Closed access)10 p

Step-Related Growth Phenomena on Exact and Misoriented {001} Surfaces of Cvd-Grown Single-Crystal Diamonds

Contains fulltext : 28533.pdf (publisher's version ) (Open Access