Bulk AlN substrates are an ideal solution for the growth of ultraviolet-C light emitting diodes (UVCLED). They are optically transparent at this wavelength and closely lattice and thermally expansion matched to the layers required for the device structure. In addition pseudomorphic growth can be achieved allowing for low dislocation density in the active region of the device [1]. This approach has been used to achieve the best efficiency and output power [2], as well as lifetime [3], in the 265 nm wavelength range. However, currently these substrates are only available in limit quantities and sizes preventing large scale manufacturing such as is occurring with visible LEDs. Regardless, we have been able to succeed in setting up pilot production of UVCLEDs to enable low volume manufacturing and allow for rapid increase in volumes as supply and size of the AlN substrates are increased.
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