氧化鋅奈米柱/硒化鎘量子點奈米複合材料之光學性質研究

Abstract

本研究觀察到氧化鋅奈米柱與硒化鎘量子點的複合材料具有比單純的氧化鋅奈米柱更顯著之光電流轉換特性，這潛在的機制是藉由改變硒化鎘量子點的大小來控制硒化鎘量子點在真空中的能階使得硒化鎘導帶位置高於氧化鋅的導帶，當激發光入射時將造成電子電洞對的產生，位於硒化鎘上的電子將遷移到氧化鋅奈米柱上並與電洞分開降低它們再結合的機率，這樣的結果能幫助傳導，我們可以發現其電流呈現一種線性的情況而且比單純的氧化鋅奈米柱產生的光電流還高。同時由於硒化鎘幫助光的吸收我們也可觀察到在可見光區的光響應程度比純氧化鋅高，這樣的結果對於我們發展高效率且涵蓋大範圍波長的光偵測器有很大的幫助

A large enhancement of photocurrent has been observed in the composite of ZnO nanorods and CdSe/ZnS quantum dots (QDs). The underlying mechanism can be attributed to the type II band alignment between ZnO and CdSe materials. After photoexcitation, the electrons and holes will be spatially separated, which will reduce the probability of recombination and enhance the detected photocurrent. Because of the absorption of CdSe QDs, the responsivity of the sample is much higher than that of pure ZnO nanorods at ultraviolet region. Besides, it is found that the spectrum of photoresponse now can cover from UV to visible region. This result is helpful to develop high efficient photodetectors with a wide range response.