Structural, optical, thermal, mechanical and dielectrical characterizations of γ-glycine crystals grown in strontium chloride solution

γ-glycine (GG) was synthesized from α-glycine in an aqueous solution of strontium chloride. A solubility study of the synthesized GG sample was conducted at various temperatures ranging from 30 to 55 °C. The saturated solution of GG was prepared using solubility data, and single crystals of GG were grown over a period of three weeks by the slow evaporation method at room temperature. The grown GG crystals were characterized by single-crystal x-ray diffraction analysis, UV–visible transmittance studies, thermogravimetric/differential thermal analysis studies, dielectric studies and Fourier transform infrared studies. The mechanical behavior of the crystals was assessed by Vickers microhardness measurements. The second-harmonic generation efficiency of the sample was measured using a Nd:YAG laser and the value was observed to be larger than that of potassium dihydrogen orthophosphate (KDP).

Source:IOPscience

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200-mm GaN-on-Si Based Blue Light-Emitting Diode Wafer with High Emission Uniformity

We investigated the emission wavelength uniformity of 200-mm GaN-on-Si based blue light-emitting diode (LED) wafer grown by metalorganic vapor phase epitaxy (MOVPE). The larger the Si substrate diameter becomes, the more difficult to obtain uniform distribution of the emission wavelength because of the larger bow during growth, resulting in larger on-wafer inhomogeneity in growth temperature. Owing to the GaN-on-Si buffer strain management, optimized gas flow condition, and precise control of temperature balance in a reactor, we have achieved high thickness and crystal quality uniformity over the 200-mm GaN-on-Si based blue LED wafer. As a result, excellent blue photoluminescence emission wavelength uniformity from the InGaN-multi-quantum wells can be demonstrated on a 200-mm wafer with a standard deviation of 2.53 nm (0.57%). Less wavelengths binning with these highly uniform emission over the 200-mm wafer show the capability of sustainable cost reduction in LED fabrication based on GaN-on-Si technology.

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net,

send us email at angel.ye@powerwaywafer.com or powerwaymaterial@gmail.com