Controlled Synthesis and Integration of Semiconductor Nanowires

October 21, 2005
Dr. Sungsoo Yi, Molecular Technology Laboratory, Agilent Laboratories


Abstract:
One-dimensional nanostructures such as carbon nanotubes (CNTs) and semiconductor nanowires (NWs) have attracted increasing attention in recent years due to their unique physical properties and potential applications in electronics, photonics and life science. Although individual nanodevices based on CNTs and semiconductor NWs have been demonstrated, methods that can enable assembly and integration of these building blocks into various device architectures over in a controlled manner need to be developed further in order to realize their full potential in a wide range of applications. In this presentation, I first demonstrate the fabrication of large-scale arrays of individually seeded, electrically addressable Si NWs with controlled dimension, placement, and orientation by utilizing both bottom-up and top-down approaches. Si NWs are an especially promising candidate for developing biochemical sensors and high-speed field effect transistors because of their several appealing properties. A single Si NW was successfully grown from each lithographically defined catalyst site in the array. The diameter, position and density of Si NWs can be controlled to create desired arrays through lithographic means. The as-grown Si NWs on the SiO2 surface were randomly oriented and ion beam irradiation was employed to align the Si NWs to desired direction. I then present the results of the epitaxial growth of highly aligned, single-crystalline InP NWs on Si substrates. There has been a great deal of interests in the heteroepitaxial growth of III-V compound semiconductors on Si, because the integration of high-performance III-V materials with the dominant Si technology could open many new applications in optoelectronics. However, fundamental issues such as large lattice and thermal expansion mismatches and differences in crystal structures have hampered epitaxial integration of III-V materials on Si. I demonstrate bridging of InP nanowires laterally grown between two vertical, (111)-oriented Si surfaces. This method of forming connected nanowires offers a new approach to the integration of III-V nanoelectronic and photonic devices with Si and provides a new degree of freedom in the design of heterojunction nanodevices combined with Si technology.


Bio
Dr. Sungsoo Yi is a scientist at Agilent Laboratories. He received a Ph.D. in Physical Chemistry from the University of Wisconsin-Madison and did a postdoctoral research in the Department of Chemical engineering, University of Wisconsin-Madison. Since joining Agilent Laboratories, he has been working on the development of various III-V compound semiconductors such as InP/GaAsSb-based heterojunction bipolar transistors and terahertz light source materials using chemical vapor deposition (CVD). His current research focus is on the synthesis of semiconductor nanowires and carbon nanotubes using chemical vapor deposition for optoelectronic and life science applications.