Silicon-Germanium Epitaxial Core-Shell Nanowire Heterostructure Devices
L. J. Lauhon, M. S. Gudiksen, and C. M. Lieber
Harvard University, US
Keywords: nanowire, heterostructure, CVD, transistor, silicon, germanium
Semiconductor heterostructures are central to the planar semiconductor industry since they enable the passivation of interfaces and the generation of devices with diverse function. We demonstrate the synthesis of silicon and germanium core-shell and multi-shell nanowire heterostructures using a chemical vapor deposition (CVD) method that is applicable to a variety of nanoscale materials. Transmission electron microscope (TEM) investigations of the growth of boron-doped silicon shells on intrinsic silicon and silicon-silicon oxide core-shell nanowires show that homoepitaxy can be achieved at relatively low-temperatures on clean silicon, and electrical transport measurements attest to the quality of the crystalline shells. TEM studies of silicon-germanium core-shell nanowires demonstrate the possibility of heteroepitaxial growth of crystalline Ge-Si and Si-Ge core-shell structures. Transport measurements of modulation-doped Si-Ge heterostructures verify that band-offsets can drive hole-injection into either germanium core or shell regions. The generality of the radial heterostructure fabrication method was explored with the growth of several core-multi-shell structures, including a high-performance coaxially-gated p-channel field effect nanowire transistor. The ability to produce a wide-range of radial nanowire heterostructures offers the potential to produce significantly improved and/or new nanodevices not possible with single component nanowires and carbon nanotubes.
NSTI Nanotech 2003 Conference Technical Program Abstract