Researchers at Pennsylvania State, Cornell University and Northwestern University, have created a ferroelectric material that can operate on silicon. The technology, commonly found in proximity-powered smart-cards today, allows certain transistors to retain their electrical state even when the power is shut off. In theory, it could allow for instant-on computers to become a reality.
The researchers refer to the technology as a hybrid transistor. Its application perfects previous attempts which had difficulty adhering the material to silicon through some type of chemical deposition process. The technique they’ve identified uses strontium titanate, which is a variant of the zirconium titanate or strontium bismuth tantalate ferroelectric materials used in smart-cards today, and chemically deposits it on silicon.
While strontium titanate in its relaxed state is not ferroelectric in any way, according to researchers at Cornell, the researchers have demonstrated that under a few atomic layers of oxygen, the strontium titanate becomes “squeezed” by about 1.7%. This tiny difference in the material drastically alters its properties and turns it into a material with useful memory properties, according to Darrell Schlom, principal investigator and professor of Materials Science and Engineering at Penn State.
Using the squeezed strontium titanate, circuits have been constructed in the lab which retain their state even when power is not applied.
The process is not yet ready for commercial application, though this breakthrough is being heralded as a major step forward. The requirements of depositing the material accurately in a bulk process are still potentially years away from being seen.
Schlom said “It would be instant-on, meaning as soon as the power comes back on, your computer would be in exactly the same state it was when you turned it off and ready for action.”
Ferroelectric transistors have been known about since 1955 when Bell Labs scientists first identified their benefits.
The paper’s first author is Maitri P. Warusawithana, a postdoctoral associate in Schlom’s lab. Other Cornell collaborators were David Muller, professor of applied and engineering physics, and graduate student Lena Fitting Kourkoutis. The team also involved scientists at the University of Pittsburgh, National Institute of Standards and Technology, Pennsylvania State University, Northwestern University, Motorola Corp., Ames Laboratory and Intel Corp.
The research was funded by the National Science Foundation, the Office of Naval Research and the Department of Energy.
As Schlom says, “Exactly” is the key word here. Such a system would allow the silicon to be signaled internally and automatically whenever the device is shutting down. At that very instant, data would be copied from the electrically-charged high-speed transistors that populate modern silicon chips today, to be deposited into tiny pools of this type of ferroelectric transistor-based memory, which are distributed around the CPU’s internal layout and are designed to hold specific internal logic unit state data. This essentially retains the entire machine’s exact state at the time of the signaling.
When the power-on sequence later occurs, everything is copied from the ferroelectric transistors to the appropriate logic units, and the CPU comes back alive and continues exactly from where it left off, and without delay — and without reading data back into memory from the hard drive as is done today on OS-level auto-resume functions, this technology would be in silicon.
Such a restart would allow mid-activity operations, such as editing a spreadsheet or viewing a webpage to reappear instantly, or certainly within a fraction of a second at most as some internal devices which are powering back on may have to re-authenticate to their network or BIOS hosts.
In short, this immediate power-up sequence would result in a computer that never had to be rebooted — provided there were no software errors — as its entire design would be built around the concept of saving the exact state for later restoration when power-on is re-applied, and being part of such a global concept in design.
In fact, if we took this idea to the extreme, a large portion of the computer could put itself to sleep automatically using these ferroelectric materials in various components, and it could do so within nanoseconds of a recognized lull in activity. A new, deeper sleep state could be achieved whereby the machine puts parts of itself into a deeper state of sleep than is possible today, but without any observable changes in performance because it could instantly return to full operations by copying data from the saved ferroelectric state to normal transistors.
Note also that MRAM, which is called magneto-resistive random access memory, has been researched for many years. There are MRAM products which exist today, though they are prohibitively expensive for general PC use. However, their memory architecture results in something similar to this ferroelectric deposition process, in that the state of every bit is maintained with MRAM even when the power is turned off.
If this technology could ever be perfected and brought to price parity with existing DRAM solutions, then the realization of instant-on devices would be completely pervasive as MRAM’s data processing speeds are nearly identical to those of DRAM, meaning the entire design utilizing DRAM components could be replaced with MRAM components, and the associated realization of the new “always has data regardless of power state” could be applied with all added benefits to the electronic device being realized.
This technology is coming. In one for or another. And when we get it, within five years it will completely change everything about servers, desktops, notebooks, netbooks, MIDs, handhelds, mobiles and related gadgets. Nothing will be unaffected by MRAM or this type of instant-on transistor.