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Defective regions of LED epi-wafers and chip-wafers could be observed by a photoluminescence (PL) imaging method. As the defective regions contain high density nonradiative recombination centers, the LED chips with defective regions showed different optical properties from those of LEDs with no defective regions found by PL imaging. At low optical excitation power levels, the PL properties were influenced...
Photoluminescence (PL) imaging is employed in order to inspect InGaN/GaN LED epi-wafers. The image shows a map of integrated PL intensity over the wafer and dark spots with degraded luminescence properties. Dark spots with various sizes indicate areas with nonradiative defects showing that the nonradiative recombination coefficient increases with the size. The PL images are compared with data obtained...
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