| dc.description.abstract | 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. | en_US |