|About this Abstract
||2010 Electronic Materials Conference
||TMS 2010 Electronic Materials Conference
||FF2, Size Effects in Semiconductor Nanowire Synthesis at the Ultimate Limit
||Shadi A Dayeh, Eli Sutter, Peter Sutter, S. T. Picraux
|On-Site Speaker (Planned)
||Shadi A Dayeh
Progress in the synthesis of semiconductor nanowires has prompted intensive discussions of the science of their growth and the technological applications they promise. While for many applications, nanowires with bulk-like electronic properties are sufficient, devices with novel functionality, such as single electron logic, or solar cells utilizing exciton multiplication, ultimately require harnessing the quantum confinement effects that arise in ultrathin nanowires with diameters below 10 nm. At this scale, the processes involved in the widely used vapor liquid solid (VLS) technique for nanowire growth remain poorly understood. Also a minimum size below which the VLS process can no longer be used for nanowire synthesis is anticipated based on thermodynamic considerations. Here we exploit an extreme level of diameter and placement control in the VLS synthesis of germanium nanowires to establish systematic size effects at small diameters and the ultimate nanowire diameters achievable in VLS growth. Our experiments demonstrate a decrease in the nanowire growth rate at lower diameters, and a concomitant increase in the equilibrium Ge concentration of the liquid Au-Ge drop mediating VLS nanowire growth. Both effects are described quantitatively by an analytical model, based on the Gibbs-Thomson effect. Combining experimental data and this model, we establish the minimum nanowire diameter, and its dependence on growth parameters such as temperature and the addition of dopants. Our results provide a rational basis for the synthesis of semiconductor nanowires at the ultimate size limit.