| Summary: | 碩士 === 國立清華大學 === 電子工程研究所 === 93 === Because of the breakthrough of epitaxy of GaN based LEDs, and due to it`s high
band gap characteristics and variation by changing the concentration of Al, In and Ga, it becomes the most popular material for UV to green light LEDs. Recently, the efficiency of blue LEDs with sapphire as substrate has been great improved, combining with yellow phosphor, white light LEDs was successfully fabricated in this way. Although the color rendering, total efficiency and price of the white light LEDs still can not have the competition with that of fluorescent light, but one day if we break the physical limitation of GaN based LEDs and enhance it`s light extraction and internal quantum efficiency, general solid state lighting is not an impossible mission for us.
In order to enhance the current usage efficiency of GaN based LEDs, and solve the problem of current crowding effect in blue LEDs with sapphire as substrate, we reduced the dimension of effective lighting area of LEDs from 15um to 3um square by traditional photo lithography method, finishing the micro LEDs array fabrication. Multi-Probe Nano-Electronics Measurement System and micro PL system are used to analyze the electrical and optical properties of individual micro LED. To analyze the electrical properties, we set the distance is the same from the n-type and p-type contact within the same dimension, and the other case is the same distance but different dimensions, therefore, we can understand what is the main point of the series resistance within individual micro LED. Besides we can analyze it`s micro PL measurement result and wish to observe whether it has optical mode within the structure or wave length shift as the size variation.
|
|---|
