| 摘要: | 本篇論文主要為分析氮化銦量子點的表面形貌、結構與光性。首先從表面形貌的估計出量子點的尺寸與高度，再從結構上探討材料應力與量子點尺寸和高度的變化，最後討論小尺寸量子點之光子能量藍移與量子效應之關聯性。 氮化銦量子點是利用有機金屬化學氣相沉積系統來成長。以單晶矽晶圓做為成長氮化銦量子點之基板，接著在高溫下(約1050度C)成長氮化鋁緩衝層，最後用間歇性的方式成長氮化銦量子點。 量子點形貌的量測是利用原子力顯微鏡(AFM)與掃瞄式電子顯微鏡(SEM)。AFM的二維影像圖經IMAQ影像處理軟體分析，得到氮化銦量子點尺寸與高度的估計值；而從EDS的分析，則發覺樣品的成份有Al,N,In。樣品的成份在X光粉末繞射實驗中，發現到氮化銦(0 0 2)面訊號，且其峰值位置有隨著量子點尺寸與高度偏移的現象，分析結果發現當量子點平均高度低於60nm時，有沿著c軸上約0.11~0.22%的伸張應變(tensile strain)產生，推測為氮化銦與氮化鋁晶格不匹配所造成。最後在光性的分析上，發現平均高度約60nm的量子點其光子能量0.82eV，與薄膜之光子能量0.75eV相差70meV，但是否為量子效應造成的藍移現象，尚須作進一步的驗證。 This thesis mainly analyzes the morphological, structural and optical properties of InN quantum dots(QDs). First, we estimate the size and height of QDs from morphological properties, and then we discuss the material strain and the variation between heights and sizes of QDs from structural properties. Finally, we talk about the relation between blue shift of small QDs and quantum efficiency from optical properties. InN QDs grows with the use of MOCVD. Then we use Si wafer as substrate to grow InN QDs, and then AlN buffer layer will grow under high temperature(about 1050 oC) onto substrate, finally, InN QDs will grow internally onto buffer layer. The way we measure the morphology of QDs is by using AFM and SEM. We estimate the size and height of InN QDs with analysis of 2-D image of AFM through IMAQ software; and from the analysis of EDS, we find the composition of sample are Al, N and In. In XRD experiment, we find the signal of InN(002), and it’s peak position would shift with size and height of QDs. When the average height of QDs is lower than 60nm, the tensile strain will occur by 0.11~0.22% along c-axis. We guess it is because InN and AlN mismatch. Finally, from optical analysis, the photon energy of QDs which average height is about 60nm is 0.82eV, which is different from that of thin film 0.75eV by 70meV. Whether the blue shift is resulted from quantum efficiency, more testimonies are necessary. |
