GaN/AlGaN single quantum disks on GaN nanorods were grown on Si (001) substrate with native SiO_2 layer by a plasma-assisted molecular-beam epitaxy under nitrogen-rich conditions. The transmission electron microscopy observations show single GaN nanorods images with an average thickness of 4 nm for the GaN single quantum disk and nanorod diameter of 15 nm. The observed photoluminescence spectra at 8 K show a peak at 3.475 eV, attributed to an exciton recombination in GaN. A strong peak was observed at 3.542 eV. This peak is attributed to the quantum confinement of excitons in the GaN quantum disks.
Growth of thin metal films on semiconductors has been always an important subject for extensive experimental and theoretical studies. As the applicability of well-ordered nanostructures in electronic applications depends strongly on their size and distribution, it is necessary to understand the processes that govern the growth of such structures. In this paper we present the results of investigation of the room temperature growth of thin Bi film on Si(111). In our study we clarified that rotationally disordered, pseudo-cubic Bi(012) islands with uniform height of ≈13Å are formed in the initial stage of Bi film growth. With increase in the amount of bismuth on the surface, islands interconnect maintaining however their uniform height. This process is further accompanied by the unique and unexpected structural phase transition of the Bi(012) film into a hexagonal Bi(001) film.
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