MBE Growth of IV-VI Nanowires on a Self-organized Template
- PDF / 1,522,454 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 106 Downloads / 176 Views
1258-P04-56
MBE Growth of IV-VI Nanowires on a Self-organized Template Lee A. Elizondo1,2, Patrick J. McCann2, Joel C. Keay3, and Matthew B. Johnson3 1 Raytheon Vision Systems, Goleta, CA 93117. 2 School of Electrical and Computer Engineering and CSPIN: Center for Semiconductor Physics in Nanostructures, University of Oklahoma, Norman, Oklahoma 73019. 3 Homer L. Dodge Department of Physics and Astronomy and CSPIN: Center for Semiconductor Physics in Nanostructures, University of Oklahoma, Norman, Oklahoma 73019.
ABSTRACT In this work, we describe the growth and characterization of low-dimensional IV-VI semiconductors as they evolve from one-dimensional dot/dot-chains to one-dimensional structures on a self-organized template epitaxially grown on Si(110). In situ and ex situ characterization were performed at various stages throughout growth by reflection high energy electron diffraction, scanning electron microscopy, and non-contact atomic force microscopy. Initial growths resulted in some preferential alignment of the PbSe dot-chains parallel to the selforganized template in the [-110] direction. By reducing the substrate temperature and increasing the supplemental Se flux, the morphology of dot-chains extend into lengthened one-dimensional structures. This is an important milestone in the fabrication of PbSe quantum wires on technologically relevant silicon. INTRODUCTION In comparison to III-V semiconductor materials, low-dimensional IV-VI semiconductors such as PbSe and related alloys are relatively unexplored even though IV-VI epitaxial layers have been shown to be compatible with silicon substrates. Recently, IV-VI semiconductor nanostructures are drawing more interest due to their unique material properties and the technologically important infrared wavelength range in which they emit [1-5]. Unlike most III-V materials where the maximum of the valence band occurs at the gamma point, IV-VI semiconductor materials have a direct band gap with nearly symmetric conduction and valence bands, which are located at the four equivalent L-points in the Brillouin zone. The symmetric bands and high dielectric constants of IV-VI semiconductors result in good confinement for both the electrons and holes in low-dimensional structures, while the large exciton Bohr radius (PbSe 46 nm) allows for quantum size effects to be observed more readily in these materials. One promising approach for the fabrication of IV-VI semiconductor multilayer nanostructured systems is initially to grow a 400-nm-thick layer of CaF2 on Si(110)-oriented substrates. This results in a self-organized template with ridges and grooves running parallel in the [-110] direction. The grooves typically vary in depth from 5 to 20 nm for a 400-nm-thick CaF2 layer and provide a suitable template for the growth of zero- or one-dimensional nanostructures. In this research, we investigate the epitaxial growth of zero- (0-D) to onedimensional (1-D) nanostructures and their characterization at various stages of the growth process on a self-organized template on silic
Data Loading...
