Study on fabrication of three-dimensional nitride semiconductors based light emitting diodes and their applications

Abstract

As the efficiency of nitride semiconductors based light-emitting diodes (LEDs) has been dramatically improved, they are widely used as both a lighting source and the backlighting unit in display. Recently, the micro-LEDs based display is also considered as the next generation display due to a number of advantages compared with current technologies for display. However, the poor color rendering and high color temperature are pointed out as problems in the case of white LEDs for lighting, and a micro-LED based displays are facing a great difficulty in commercialization due to the absence of mass-transferring method. These occur because the conventional LEDs emit only single wavelength on the single substrate. In this dissertation, we tried to solve the problems by fabricating the three-dimensional (3D) structures-based LEDs. For the lighting application, a highly efficient phosphor-free warm white LEDs were successfully demonstrated by using 3D dodecagonal ring structures fabricated by selective area growth and KOH wet etching method. Furthermore, the selective area growth technique was systematically studied, and the 3D structures capable of emitting multiple wavelength light and controlling emission wavelength are formed on a single substrate. We believe these results are expected to be applicable to technology of micro-LED based displays fabricated by non-transfer method.