15,439 research outputs found
Imaging crystal orientations in multicrystalline silicon wafers via photoluminescence
We present a method for monitoring crystal orientations in chemically polished and unpassivated multicrystalline silicon wafers based on band-to-band photoluminescence imaging. The photoluminescence intensity from such wafers is dominated by surface recombination, which is crystal orientation dependent. We demonstrate that a strong correlation exists between the surface energy of different grain orientations, which are modelled based on first principles, and their corresponding photoluminescence intensity. This method may be useful in monitoring mixes of crystal orientations in multicrystalline or so-called “cast monocrystalline” wafers.H. C. Sio acknowledges scholarship support from
BT Imaging and the Australian Solar Institute, and the
Centre for Advanced Microscopy at ANU for SEM access.
This work has been supported by the Australian Research
Council
Imaginary Potential Induced Quantum Coherence for Bose-Einstein Condensates
The role of complex potentials in single-body Schr\H{o}dinger equation has
been studied intensively. We study the quantum coherence for degenerate Bose
gases in complex potentials, when the exchange symmetry of identical bosons is
considered. For initially independent Bose-Einstein condensates, it is shown
that even very weak imaginary potential can induce perfect quantum coherence
between different condensates. The scheme to observe imaginary potential
induced quantum coherence is discussed.Comment: 4 pages, 4 figure
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