Papers by Keyword: Crystalline Materials

Abstract: We report on the results of intense third party evaluation of the COLD SPLIT technology. In total nine different SiC manufactures supplied test material. The results confirm the tremendous potential of the technology with total kerf losses per wafer of less than 100μm. Furthermore, our general approach led to comparable results for all vendors. The vendor specific difference like lateral doping level were addressed via control loops in our lasering process. These loops take crystal properties into account and adjust the applied laser energy and the depth of the laser process accordingly. Even the current best case results of sub 80μm split loss per wafer are dominated by systematic effects, which are addressed by continuous improvement efforts.

Abstract: We have studied the interaction of the positron with chiral left-or right-handed quartz crystals. In Doppler-broadening experiments, using a mono-energetic positron beam there is a differential depth profile for positrons implanted in LH or RH z-cut quartz as identified by a shape parameter (S). Further, in bulk positron annihilation lifetime spectroscopy (PALS) experiments, the lifetime (τ ₂) attributed to free annihilation of the positron interacting with the chiral lattice exhibits a larger value for the LH quartz, and the associated intensity (I₂) is also significantly different—RH quartz is consistently 10% greater than the LH crystal. The τ ₃ lifetime and its intensity, I₃, attributed to positronium interacting with defects in the quartz, also appears to exhibit differences between the enantiomeric sets of crystals. These observations may demonstrate chiral recognition using a positron annihilation technique, pave the way for a broad range of positron experiments, and may help inform hypotheses of chirality recognition, selection, or induction by beta radiation.

Abstract: Nanoindentation technique has been widely used for measuring mechanical properties from a very small volume of material. The hardness measured using the depth sensing nanoindentation technique often decreases with increasing indentation size, the so called indentation size effect (ISE)[1, 2]. It has been generally acknowledged that the ISE in crystalline materials originates from the density change of geometrically necessary dislocations (GND) needed to accommodate a permanent indentation imprint. Conventionally, to characterize an ISE often requires a series measurement of hardness values at different indentation size. Based on the celebrated Oliver-Pharr scheme[3]. We propose a method to derive the ISE from the loading curve of one single indentation test. The application and limitation of the proposed method will be discussed.