Atomic Force Microscope: It's the Pits

CD-ROMs record their information in the form of tiny pits in the surface. A laser reads the information from the pits. Now CD-ROMs already hold lots of data. But what if you could make the pits really, really tiny?

How tiny? Oh, a few atoms deep. That's one of the technologies that atomic force microscopy is able to perform. An atomic force microscope (AFM) uses an extremely tiny conducting stylus that is very clo se to a surface. By placing a small charge on the tip of this stylus, it is possible to move single atoms around on the surface. (IBM scientists demonstrated this by spelling out "IBM" using individual xenon atoms.)

In this new use for the AFM, heat is applied to the stylus, which is placed on a cantilever that can rock up and down. When the cantilever moves down, it can gouge out a few atoms from the rotating surface. This writes data onto the surface. One system uses a laser to detect that there is a pit, reading the recorded data. Another system uses the stylus tip itself to read the indentations. The whole AFM shebang is actually created as part of a silicon chip-like structure, with the cantilever as a tiny moving part. After you have recorded your information once, you can stamp out duplicates in much the same way as with CD-ROMs.

This write-once/read-many storage system can achieve densities of 100 gigabits per square inch under practi cal operating systems. The upper limit seems to be about 300 gigabits per square inch. Since the AFM mechanism is essentially a solid-state system (with its one moving part), it is also a fairly stable system. But there are even bigger (or smaller) deals to come.

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AFM: In the Pits

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A Whole Lotta Data Going On

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AFM put data on this substrate at a density of 64 Gbits per square inch.