Phase Change Memory
“A data storage device is a device for recording (storing) information (data). Recording can be done using virtually any form of energy, spanning from manual muscle power in handwriting, to acoustic vibrations in phonographic recording, to electromagnetic energy modulating magnetic tape and optical discs.
A storage device may hold information, process information, or both. A device that only holds information is a recording medium. Devices that process information (data storage equipment) may either access a separate portable (removable) recording medium or a permanent component to store and retrieve information.
Electronic data storage is storage which requires electrical power to store and retrieve that data. Most storage devices that do not require vision and a brain to read data fall into this category. Electromagnetic data may be stored in either an analog or digital format on a variety of media. This type of data is considered to be electronically encoded data, whether or not it is electronically stored in a semiconductor device, for it is certain that a semiconductor device was used to record it on its medium. Most electronically processed data storage media (including some forms of computer data storage) are considered permanent (non-volatile) storage, that is, the data will remain stored when power is removed from the device. In contrast, most electronically stored information within most types of semiconductor (computer chips) microcircuits are volatile memory, for it vanishes if power is removed.
With the exception of barcodes and OCR data, electronic data storage is easier to revise and may be more cost effective than alternative methods due to smaller physical space requirements and the ease of replacing (rewriting) data on the same medium. However, the durability of methods such as printed data is still superior to that of most electronic storage media. The durability limitations may be overcome with the ease of duplicating (backing-up) electronic data.”(Wikipedia, Data Storage Devices, 6/25/2012)
In certain embodiments, an electroactive (redox-active) molecule such as a porphyrin and/or metallocene is covalently attached (directly or through a linker) to a conductive surface such as gold or silicon. The electroactive molecule(s) can be oxidized, e.g., to a cationic state upon application of an applied potential. When the potential is removed, the molecules store charge for extended periods. This forms the basis of the memory storage device.
General challenges in fabricating a hybrid chip containing molecular materials for information storage include, but are not limited to the efficient and effective attachment (electrical coupling) of the charge-storage molecule to an electroactive surface, controlling placement of the charge storage molecule(s) and/or associated electrolyte(s), and controlled deposition/location not counterelectrodes. Particularly pressing problems are that often the methods for attachment of molecules to surfaces often require very high concentrations, high temperature, and/or the use of reactive intermediates (see, e.g. Cleland et al. (1995) J. Chem. Soc. Faraday Trans. 91: 4001-4003; Buriak (1999) Chem. Commun. 1051-1060; Linford et al. (1995) J. Am. Chem. Soc. 117: 3145-3155; Hamers et al. (2000) Acc. Chem. Res. 33: 617-624; Haber et al. (2000) J. Phys. Chem. B, 104: 9947-9950). Such conditions are readily applicable to small robust molecules but become less satisfactory and often fail altogether as the molecules become larger and/or more elaborate.
Another problem is associated with increased miniaturization of the electroactive memory elements. As the feature size of a memory cell shrinks to nanoscale dimensions, fewer and fewer molecules occupy the cell feature. Consequently, it becomes increasingly difficult to detect the stored charge
[Bocian, Liu and Lindsey, US Patent 8,231,941 (7/31/2012)]
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Roger D. Corneliussen
Maro Polymer Links
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Copyright 2012 by Roger D. Corneliussen.
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* Date of latest addition; date of first entry is 6/25/2012.