Milliwatt power 233nm AlGaN-based deep UV-LEDs on sapphire substrates

Deep UV-LEDs (DUV-LEDs) emitting at 233nm with an emission power of (1.9 +/- 0.3) mW and an external quantum efficiency of (0.36 +/- 0.07) % at 100mA are presented. The entire DUV-LED process chain was optimized including the reduction of the dislocation density using epitaxially laterally overgrown AlN/sapphire substrates, development of vanadium-based low resistance n-metal contacts, and employment of high thermally conductive AlN packages. Estimated device lifetimes above 1500 h are achieved after a burn-in of 100 h. With the integration of a UV-transparent lens, a strong narrowing of the far-field pattern was achieved with a radiant intensity of 3 mW/sr measured at 20mA.