역 나노 임프린팅 방식을 이용한 2차원 TiO2 나노입자 광결정 구조 형성 및 발광 다이오드에서의 응용 연구

Abstract

ABSTRACT

A Study on reversal nano-imprint lithography of the TiO2 nanoparticles and its application to 2-Dimensional patterned light emitting diode

At this time when integration of elements is important issue of process, the Nano-imprint lithography(NIL) process which has low cost and simple process and is the process of production of minute structure is drawing attention as the next-generation lithography process. In addition, Light Emitting Diode(LED) is used in various fields on the foundation of merit that it is quick and has low electric power consumption, long lifetime, high luminous characteristics and is environmentally friendly element. Particularly, white LED is called "The Revolution of Illumination" and many researches are being progressed on it. The purpose of this experiment is to understand the patterning technology using reverse nano-imprint technology(RIL) and using this to understand the possibility of realization of white LED. For theoretical contemplation of the experiment, phosphor, photonic crystal, quantum dot, and the concept and the principle of light emitting of LED were investigated. In addition, existing methods for realization of white LED and imprint techniques used in the experiment were understood. The progression of experiment is started as producing master stamp mold of SiO2 which has two dimensional photonic crystal structure, and making replica mold using PDMS. The flexible characteristics of PDMS enabled the imprint process on LED package which has ups and downs. The experiment was progressed as reverse-imprint process, and the two substances TiO2 nano particles and green quantum dot were mixed to be used as imprint resin. The formed two dimensional photonic crystal together with high refractive substance TiO2 was expected the enhancement of efficiency. And the green quantum dot were mixed with blue LED light source and used for the purpose of forming white LED. As the result of study, it can be confirmed that SiO2 master stamp mold was formed as two-dimensional photonic crystal structure which has tripodal placement structure. In addition, it can be confirmed through SEM image that imprinted pattern also has the shape like the master stamp mold. The electro luminescence (EL) of pattern made was measured for evaluation of efficiency and in order to understand the possibility of white LED, CIE color coordinate also was measured. Though the pattern made through the experiment could not realize perfect white LED, it could be seen that it was going toward white light source. This showed the possibility of white LED through adjustment of ratio of quantum dots and it would make it possible to realize white LED through follow-up study progression.