國立臺灣大學電機工程學系暨研究所管傑雄2006-07-252018-07-062006-07-252018-07-062002-07-31http://ntur.lib.ntu.edu.tw//handle/246246/7879在本子計畫中，我們將發展光電流 雜訊的量測技術來研究這些區域性能階 的光電特性；尤其是它們對導電帶電子 及價電帶電洞等生命期的影響。這些參 數是設計雷射及偵檢器等元件的重要參 數。單靠簡單的I-V 或光譜量測是無法得 知生命期的大小；但它們卻反應在光電 流的雜訊上。由量測元件光電流的雜訊 功率，求其與4eIph(Iph 為光電流)的比值， 可得到雜訊電流增益。該值為載子生命 期與過渡時間之比。過渡時間為載子經 過樣本所需的時間，可以藉由改變樣本 大小或外加電壓值而調整。如此由雜訊 電流增益所求得生命期的最小值，可以 不受限於儀器的頻率分析能力，此為整 套系統最大的優點。 本子計畫預計以二年的時間持續發 展此光電流雜訊量測技術，所針對的元 件分別為GaN bulk、量子井及點、具有 C-base 的奈微米結構。其中的GaN bulk 是研究其雜質或者是defects 所造成的區 域性能階；而其他的則是結構所導致的 區域性能階。除了量測光電流雜訊外， 我們也將針對各元件進行FTIR紅外線吸 收光譜實驗、photoluminescence 實驗、 拉曼吸收光譜實驗、以及step scan FTIR 發射光譜實驗。綜合各實驗所得的結 果，以便瞭解生命期中radiative transition 與nonradiative transition 的相對大小，以 及造成nonradiative transition 的主要原 因。在未來的計畫中，我們將沿用這些 成果，持續發展利用奈微米結構所設計 出的光電元件。In this proposal, we will develop a technique to measure the noise power of the photocurrent to investigate the localized states. In particular, the associated lifetime of the free carriers with the localized states is our primary interest. The carrier lifetime is an important parameter for those devices such as laser diodes and detectors. With simple measurement of I-V characteristics or absorption spectrum, we can not determine its value. However, it can be derived from the noise power of the photocurrent in the devices. The ratio of the photocurrent noise power over 4eIph where Iph is the photocurrent gives the noise current gain. The noise current gain also equals the ratio of the lifetime over the transit time. In average, a free carrier passes through the sample in a transit time. Its magnitude may be changed with the sample length or the applied voltage. Therefore, the lifetime measured with the photocurrent noise is not limited by the frequency capability of the measurement system. This is the best advantage of this method to measure the carrier lifetime. In the future three years, we will keep going on the development of the measurement technique of the photocurrent noise. The devices we will investigate are involved with the GaN bulk, quantum wells, quantum dots, or C-base nanostructures. For the GaN bulk, we will study the localized states caused by the impurities and defects while for the others, the localized states by the nanostructures. In addition to the noise measurement, we will also proceed the measurements of the FTIR absorption spectrum, photoluminescence, Raman absorption spectrum, and step scan radiation spectrum. Based on all the experimental results, the lifetime can be analyzed for which of the radiative or nonradiative transitions is more important. In particular, the mechanism rendering the nonradiative transition is our primary concern. In the future plan, all of the results derived from this proposal will be utilized to design the optoelectronic devices with such nanostructures.application/pdf160408 bytesapplication/pdfzh-TW國立臺灣大學電機工程學系暨研究所區域性能階奈微米結構量 子井量子點雜訊量測localized statenanostructurequantum wellquantum dotnoise measurementreporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/7879/1/902215E002024.pdf