Simultaneous STM and UHV electron microscope observation of silicon nanowires extracted from Si(111) surface

A miniaturized scanning tunnelling microscope (STM) was fitted in a side-en try holder of an ultra-high vacuum electron microscope. The clean Si(111)7 X 7 surface was observed by both STM and reflection electron microscopy (RE M) at. atomic resolution. The tungsten rips were often rounded off upon tip -approach with a constant current, through a gentle touch with the sample s urface. The apices of such rounded tips had radii of several tens of granom etre with widths of about 3 x 3 nm. Atomically resolved STM of the Si(111)7 X 7 surface was obtainable when an atom or an atomic cluster sits on the t ip surface. The rounded lips were used for fabrication of Si nanowires by t he touch-and-away operation of the tip. The nanowires grew longer at higher substrate temperature and they reached as long as several tens of nanometr e at 700 degrees C. The nanowire had many twins and the (111) twin lamellae were stacked in the direction of the wire axis. In another case, the twin planes were oblique to the wire axis so that the < 112 > direction was near ly parallel to the wire axis.