Advanced Coherent X-ray Diffraction and Electron Microscopy of Individual in P Nanocrystals on Si Nanotips for III-V-on- Si Electronics and Optoelectronics

The nondestructive detection and evaluation of crystallographic properties of nanocrystals is of great significance for both fundamental physics research and further development of high-performance functional devices employing nanostructured materials. Synchrotron radiation-based CXD using a nanoscale x-ray beam is shown to be a powerful tool to explore the crystallographic properties of InP nanocrystals (NCs) selectively grown on Si nanotip wafers. CXD characterization clearly clarifies, with atomic sensitivity and without complex sample preparation, the crystallographic properties of the selected InP NC such as the structure of the facets, the strain, the existence of defects (stacking faults and microtwins), and the size of the defected crystallites. Several selected InP NCs explored by CXD reveal homogeneous structures. The CXD results are in good agreement with electron microscopy. These results not only confirm that nanoheteroepitaxy is a promising approach to monolithically integrate high-quality III-V compounds on silicon wafers, but also opens a pathway to nondestructively explore the crystallinity of materials on the nanometer scale, particularly in nano-electronic and nano-optoelectronic devices.