Electrical spin injection and detection in Si nanowires

While electrical spin injection and detection in bulk Si has now been established, the availability of high quality single crystalline silicon nanowires has stimulated considerable interest in demonstrating spin-polarized transport in these 1-dimensional structures. Here, we report our efforts to electrically inject spin-polarized electrons from cobalt contacts into n-type silicon nanowires through Al$_{2}$O$_{3}$ tunnel barriers. The electrically doped nanowires were synthesized by the vapor-liquid-solid process with a cold wall chemical vapor deposition system using silane and phosphine precursors. Low temperature magneto-transport studies have shown spin-valve like behavior in both two-terminal and four-terminal lateral devices. The spin-valve signal as functions of temperature and bias voltage will be discussed. We will also show the influence of defects and trap states on the stability of nanowire devices.