Ultrahigh data density storage with scanning tunneling microscopy

Ultrahigh density data storage devices made by scanning probe techniques ba sed on various recording media and their corresponding recording mechanisms , have attracted much attention recently, since they ensure a high data den sity in a non-volatile, erasable form in some kinds of ways. It is of parti cular interest to employ organic polymers with novel functional properties within a single molecule (or a single molecular complex) for fabricating el ectronic devices on a single molecular scale. Here, it is reported that a n ew process for ultrahigh density and erasable data storage, namely, molecul ar bistability on an organic charge transfer complex of 3-nitrobenzal malon onitrile and 1,4-phenylenediamine (NBMN-pDA) switched by a scanning tunneli ng microscope (STM). Data density exceeds 10(13) bits/cm(2) with a writing time per bit of similar to1 mus. Current-voltage (I/V) measurements before and after the voltage pulse from the STM tip, together with optical absorpt ion spectroscopy and macroscopic four-probe I/V measurements demonstrate th at the writing mechanism is conductance transition in the organic complex. This mechanism offers an attractive combination of ultrahigh data density c oupled with high speed. The ultimate bit density achievable appears to be l imited only by the size of the organic complex, which is less than 1mn in o ur case, corresponding to 10(14) bits/cm(2). We believe that provided the l ifetime can be improved, molecular bistability may represent a practical ro ute for ultrahigh density data storage devices.