These two images display "Tunnel-tip" structures. The objective is to obtain
a 'pyramidal tip' of silicon that is pointing up and is very close to a metal
pad that covers it from top. Normally, the metal pad is used for etching
a tip below it and is 'sacrificed' when the tip actually gets formed (the
pad has no supports and hence falls off). The work shown here demonstrates
a technique where a pad has been designed in such a way that it allows tip
to be etched but does not fall off.
The image on the left shows a closeup view of a single device that has the
tip just being formed below the pad. (The scale bar is 10 microns long.)
Such a device can be used for measuring tunneling currents. The image to
the right shows various cross-bridge patterns for metal pads. (The scale
bar is 100 microns long.) The work is yet to be published.
The work shown below was performed at the Tata Institute for Fundamental
Research in Bombay, India.
(These images were acquired with the NPGS Digital Imaging Feature.)