Search NASA⌕ Search

Engineering topics

Hong, H

Publications and source records attributed to Hong, H.

Real time reciprocal space mapping of nano-islands induced by quantum confinment.

The effects of quantum confinement have been observed pronouncedly in the island morphology of Pb thin films. The evolution of these nano-islands on Si (111)-(7 x 7) and sapphire (001) surfaces has been studied with a new X-ray diffraction method. A charge-coupled device (CCD) camera was used to collect two- and three-dimensional (2-D and 3-D, respectively) maps of the surface X-ray diffraction in real time. Large ranges of the reflectivity curves, with rocking curves at every point on the reflectivity curves, could be measured continuously in a relatively short amount of time. The abundance of information from 2-D k-space maps reveals clear changes in the growth modes of these thin Pb films. With the 3-D extension of this method, it was possible to observe the ordering of the islands. The islands maintain a nearly uniform interisland distance but lack any angular correlation. The interisland ordering is correlated well with the development of 'magic' island heights caused by quantum confinement.

36 MATERIALS SCIENCE↗

The MAJORANA Experiment

The Majorana Collaboration is assembling an array of HPGe detectors to search for neutrinoless double-beta decay in {sup 76}Ge. Initially, Majorana aims to construct a prototype module to demonstrate the potential of a future 1-tonne experiment. The design and potential reach of this prototype Demonstrator module are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗