Noise Measurement and Analysis of Nitride-Based Light Emitting Diodes Grown on Patterned Sapphire Substrates

• Main Authors: Kuan, Chin-I, 管金儀
• Other Authors: Lin, Gray
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/93101905775992309531

碩士 === 國立交通大學 === 電子研究所 === 100 === In this thesis, the device quality of InGaN light-emitting diodes (LEDs) is investigated by studying their low-frequency noise characteristics. We firstly measurethe electrical noisespectra of LEDs under different current injection. Then the individual spectrum isfitted by empirical formula in low-frequency range. Finally the noise exponent is calculated and correlated to the LED quality. The LED samples grown on controlled substrates are intentionally selected for noise characterization, they are: (1) LEDs grown on flat sapphire substrate, patterned sapphire substrate (PSS) and GaN substrate, (2) LEDs grown on first and second wet-etched patterned sapphire substrate, (3) LEDs grown on dry-etched patterned sapphire substrate with different pattern height. Analysis has shown that high quality devices are associated with large noise exponent. Since the extracted noise exponent stand for theratio of noise intensity change to incremental current,high quality LEDs thereforepossesslower noise intensityunder low injected current. By the way, we have confirmed the LED quality by separate material and defect characterization.