A Deep Learning Based Dislocation Detection Method for Cylindrical Crystal Growth Process

For the single crystal furnace used in the photovoltaic industry, growth problems occur frequently due to dislocations during the shouldering and cylindrical growth steps of the Czochralski (CZ) crystal growth. Detecting the dislocation phenomenon in the cylindrical growth step is very important for entire automation of the CZ crystal furnace, since this process usually lasts for more than 48h. The irregular nature of different patterns of dislocation would impose a big challenge for a traditional machine vision-based detection method. As almost no publications have been dedicated to detecting this phenomenon, to address this issue, after analyzing the characteristics of the silicon ingot image of this process, this paper proposes a kind of deep learning-based dislocation detection method along with tracking strategy to simulate manual inspection. The model has a good detection effect whether there is occlusion or not, the experimental results show that the detection accuracy is 97.33%, and the inference speed is about 14.7 frames per second (FPS). It can achieve the purpose of reducing energy consumption and improving process automation by monitoring this process.

Simulation of X-ray diffraction in a cylindrical crystal

Using the two-dimensional recurrence relations of X-ray dynamical diffraction, a numerical simulation of reflection and transmission intensity in a cylindrical crystal has been performed. It is shown that for crystals with a small radius Bragg diffraction is realized. For crystals of large radius, Bragg–Laue diffraction occurs, which is characterized by Bragg diffraction on the upper part of the crystal, as well as the presence of Pendellösung oscillations inside the cylindrical crystal. The reciprocal space maps of dynamical and kinematical diffraction have been calculated.

On Experimental Study of Development Calcined Gypsum from Flue Gas Desulfurization by Microwave Technology

Flue gas desulfurization gypsum (FGD gypsum) was irradiated with microwave, it could be changed calcined gypsum from flue gas desulfurization (CGD). The microwave respectively irradiated five groups FGD gypsum at 100-110°C, 110-120°C, 120-130°C, 130-140°C and 140-150°C, then the fineness and setting time were respectively measured, and compressive/flexural strength were also determined after 2 hours. Experiments show that, CaSO4·0.5H2O crystal of CGD would be more quantity and bigger volume with irradiation temperature increasing. The reason was considered that there were special effect of microwave irradiation to calcium sulfate crystalsthat by scanning electron microscope, and found the Ca, S, O and other elements in cylindrical crystal by Edax. The formation mechanism of CaSO4·0.5H2O crystal by microwave irradiation is different from traditional CaSO4·0.5H2O crystal formation theories.

Thermal Transport During Seeding and Shouldering in the Czochralski Crystal Growth

Czochralski (Cz) growth during seeding and shouldering of silicon single crystal has been studied. During seeding, the diameter increases from a small value to the desired value of the fully-grown crystal. The convection in the melt, conduction in the crystal and radiation from the melt surface and crystal, surface tension at the free surface of the melt and crystal rotation have been considered to investigate the effect of seeding on thermal transport. The rotational Reynolds number, the radiation from the crystal and Marangoni number are varied to investigate their effect on the interface shape. A few selected cases have been studied using a cylindrical crystal to understand the effect of geometry on the heat transfer rate and subsequently on the interface shape. The governing equations are solved using the curvilinear finite volume discretization scheme and the grids are redistributed using the multizone adaptive grid generation after each iteration. The movement of free surface is taken care by employing suitable equations for energy and stress balance. Results show the dependency of both the radiation from the crystal and rotation of the crystal on the interface shape.