04-08-2014, 12:16 PM
NANO TECHNOLOGY BASED DATA STORAGE
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ABSTRACT
Storing data in the storage devices such as Magnetic Tape drives, Hard drives, Floppy drives, Compact-Disc, DRAM, SRAM, FLASH, etc, is important for the information technology world. But as this industry growing on the needs of storing data is increasing tremendously. We require high data capacity, high data transfer rates. Current trend storage devices can not meet this requirement. In this medley Nanotechnology is useful to design high data compression storage devices with higher data rates. In this regard Ultrahigh storage densities of up to 1 Tb/in2. or more can be achieved by using local-probes techniques to write, read back, and erase data in very thin polymer films.
NANO-TECHNOLOGY
The construction of materials whose physical constraints such as length, area, volume rang from 1nm to 100nm. The properties of materials such as physical, chemical, etc,. at this scale are different from at usual scale.
A physicist Richard P. Feynman in December 1959 introduced this concept and he said that "There's Plenty of Room at the Bottom - An Invitation to Enter a New Field of Physics." He notified the possibility of construction of a structure by atom-by-atom from individual atoms which are precisely joined by chemical forces.
NANOTECHNOLOGY APPLIED TO STORE DATA
Silicon-based semiconductor memory chips and magnetic hard drives have been dominating the data-storage market and they have their limitations as magnetic data storage can not exceed the areal density 250 Gbit/in2. At the same time DRAM, SRAM, FLASH Memory chips having the limitations no of Transistors per chip and difficulties in decreasing feature size(2λ). These limitations can be overcome through the new innovative technology namely NANO TECHNOLOGY. Applying nanotechnology to data storage will result in memory devices with high capacity of aeral density of 1 TeraByte/square inch.
NANO-TIP
A sharp pointer type object having nano dimensions is a nano-tip are cantilever. Several of such tipscalled probe and large no.of such probes is used to write and read back data using thermomechanical method on a thin polymer film. The thermomechanical probe-based data-storage concept, millipede_, combines ultrahigh density, small form factor, and high data rates by means of highly parallel operation of a large number of probes
WRITING AND READING OF DATA
Thermomechanical writing is achieved by applying a local force through the cantilever/tip to the polymer layer and simultaneously softening the polymer layer by local heating. The tip is heated by application of a current pulse to a resistive heater integrated in the cantilever directly above the tip. Initially, the heat transfer from the tip to the polymer through the small contact area is very poor, but it improves as the contact area increases. This means that the tip must be heated to a relatively high temperature of about 400ºC to initiate softening. Once softening has been initiated, the tip is pressed into the polymer, and hence the indentation size is increased.
ADVANTAGE OF SCANNING-PROBE STORAGE
Important characteristic of a storage device is the sustained data rate for storing or retrieving information. Scanning-probe storage is inherently slow in storing or reading back information with only a single probe or sensor. Figure 6 shows the user data rate as a function of the total number of cantilevers accessed simultaneously. In this diagram, T denotes the time it takes for a probe to move from the center of a logical mark to the center of the next logical mark. Equivalently, 1/T represents the symbol rate per probe. In this scenario a (d =1, k = _)-constrained coding scheme is assumed. For example, for a 64×64 cantilever array, a system designed to access a maximum of only 256 cantilevers every T = 5 µs yields a user data rate of 34.1 Mb/s.
CONCLUSION
A very large 2D array of AFM probes has been operated for the first time in a multiplexed/parallel fashion, and write/read/erase operations in a thin polymer medium have been successfully demonstrated at densities significantly higher than those achieved with current magnetic storage systems.