Crystal Defect Analysis

Phosphor plays a key role to obtain white light as for blue LED + phosphor and near ultraviolet LED + phosphors. In order to improve high bright white LEDs, it is necessary that the whole phosphor particle emits light homogeneously. When measuring with CL the phosphor used as white LED, the area which does not emit light in phosphor particle can be observed. CL system is used for evaluation of non-luminescent area to improve luminescent efficiency and characteristics.

The characterization of synthetic CVD diamond material by hyperspectral cathodoluminescence spectroscopy and imaging allows the detection and accurate location of the promising NV luminescent point defects for innovative solid-state quantum mechanical systems. In this work we performed CVD epitaxial growth on a pattern of micro-pillars etched on a diamond substrate. Cathodoluminescence (CL) analysis revealed that NV centres were successfully localized at the edges of the pillars.

The threading dislocation occurs easily in GaN crystal grown on sapphire substrates. It is said that this is caused by the large lattice mismatch of sapphire and GaN. The crystal may seem to be uniform in the SEM image, but the dark spot such as the threading dislocation can be observed when measuring the CL intensity image at the wavelength (362nm) which corresponds to the band edge emission.