Study of focused-ion-beam irradiation effects on the III-nitride semiconductors and their application for micro-light-emitting diodes

Abstract

III-N based micro-LED have gained much attention in many research areas as a future display because of its high brightness, high stability, long lifetime, short response time, and high resolution. Also, on-going studies are in progress to improve micro-LED processing technique for the realization of high-efficiency ultra-small scale micro-LEDs, which are smaller than 10 μm size. In this study, we focused on the focused ion beam (FIB) technology that is widely used in the semiconductor industry for sub-micrometer processing. First, we measured the changes in the optical and electrical characteristics of a III-N LED wafer after He FIB irradiation. By varying the ion dose, the trends of changes in optoelectronic characteristics was analyzed. As a result, we confirmed that the He ion irradiated regions of the LED wafer were optically quenched and electrically isolated. In addition, ultra-small blue micro-LEDs of less than 1 μm were produced using the results of the previous research that proved characteristics change by FIB irradiation. We then measured size-dependent optoelectronic characteristics of the fabricated micro-LEDs, and quantitatively analyzed the decrease in power efficiency with decreasing LED size. The above findings suggest that changes in the optoelectronic characteristics of a III-N LED substrate can be induced by controlling defects inside the substrate through FIB irradiation, and this effect can be applied to ultra-small III-N device processes under sub-micrometer units.