Enhancement in emission efficiency of diamond deep-ultraviolet light emitting diode

We demonstrate high-efficiency excitonic emission with deep-ultraviolet (DUV) light of 235 nm at room temperature for a (111)-oriented diamond p-i-n junction light-emitting diode (LED) by introducing a thick i-layer. Significant enhancement in excitonic emission efficiency of over 500 times was observed for a diamond LED by increasing the i-layer thickness from 0.1 to 14 mu m. Maximum output power and external quantum efficiency of excitonic emission for the LED without any specific device structure were 0.1 mW and 0.006%, respectively, under pulsed-current injection. We also demonstrate the sterilization of Escherichia coli by irradiation with DUV light from the diamond LED. (C) 2011 American Institute of Physics. [doi:10.1063/1.3625943]