We developed a Eu 2þ -doped red-emitting Sr-containing sialon phosphor Sr 2 Si 7 Al 3 ON 13 :Eu 2þ that could play a very important role in high color rendering of white light-emitting diodes (LEDs) for solid-state lighting. It realizes both high efficiency and small thermal quenching under excitation by blue light, which are essential for operation in a high-temperature atmosphere. It shows a highly efficient red luminescence whose external quantum efficiency reaches 73% for 450 nm excitation. These features show that this red-emitting phosphor has high potential for application to white LEDs. #

To investigate the mechanism of contraction/expansion behavior of Shockley stacking faults (SSFs) in 4H-SiC p-i-n diodes, the dependences of the SSF behavior on temperature and injection current density were investigated by electroluminescence image observation. We investigated the dependences of both triangle-and bar-shaped SSFs on the injection current density at four temperature levels. All SSFs in this study show similar temperature and injection current density dependences. We found that the expansion of SSFs at a high current density was converted to contraction at a certain value as the current decreased and that the value is temperature-dependent. It has been confirmed that SSF behavior, which was considered complex or peculiar, might be explained mainly by the energy change caused by SSFs.

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We have successfully developed a white light-emitting diode (LED) for a wide-color-gamut backlight composed of a green-emitting phosphor Sr3Si13Al3O2N21:Eu2+ combined with a blue LED and a red-emitting phosphor CaAlSiN3:Eu2+. This white LED showed a discrete spectrum with distinct separation of red, green, and blue primary colors due to a narrow emission band of around 525 nm for the green phosphor. 94.2% of the wide color gamut of the National Television System Committee standard was attained by applying typical color filters of LCDs. The power LED module composed of 16 of these white LEDs revealed their excellent power dependence. The LED is expected to replace cold cathode fluorescent lamp (CCFL), and find a suitable application as a backlight in large-scale LCDs for in-vehicle use or for flat-panel television sets.

Configurations of the basal plane dislocations in 4H-SiC epitaxial layers are classified into two types, having typical combinations of ‘straight Si-core and straight C-core’ and ‘straight Si-core and curved C-core’ partial dislocations. The core species are determined by the photoluminescence images and observation of the moving Si-core partial dislocations by ultra-violet light illumination. Each partial dislocation was analyzed by photoluminescence spectroscopy. As the results, C-core partial dislocations have been found to have different peak wavelengths depending on the excitation power of the illumination. Also from the detailed analysis of individual partial dislocations, the curved C-core partial dislocations have been found to have different characters which may be originated from the mixture of different types of dislocations. It has been suggested that this model is possibly described by continuous connection of 30o and 90o dislocations which have different configurations of dangling bonds. The difference in photoluminescence peak wavelength might be explained by the structural difference.