Transparent memory devices show promise for electronics

Researchers at Rice University are designing transparent, two-terminal, three-dimensional computer memories on flexible sheets that show promise for electronics and head-up displays.

The technique was reported on 2 October in Nature Communications.

The Rice team, led by chemist James Tour and physicist Douglas Natelson, is said to be making highly transparent, non-volatile resistive memory devices based on silicon oxide’s capability as a switch.

According to a statement, a voltage run across a thin sheet of silicon oxide strips oxygen atoms away from a 5nm-wide channel, turning it into conductive metallic silicon. With lower voltages, the channel can then be broken and repaired repeatedly, over thousands of cycles.

That channel can be read as a 1 or a 0 and, at 5nm, it shows promise to extend Moore’s Law, which predicted that computer circuitry will double in power every two years. Current advanced electronics are made with 22nm circuits.

The research — by Tour, Rice’s TT and WF Chao Chair in Chemistry, as well as a professor of mechanical engineering and materials science and of computer science; lead author Jun Yao, a former graduate student at Rice and now a postdoctoral researcher at Harvard; Jian Lin, a Rice postdoctoral researcher; and their colleagues — details memories that are 95 per cent transparent and made of silicon oxide and crossbar graphene terminals on flexible plastic.

The Rice lab is making its devices with a working yield of approximately 80 per cent, which is pretty good for a non-industrial lab, Tour said. ‘When you get these ideas into industries’ hands, they really sharpen it up from there.’

Manufacturers that have been able to fit millions of bits on small devices such as flash memories now find themselves bumping against the physical limits of their current architectures, which require three terminals for each bit.

But the Rice unit, requiring only two terminals, makes it far less complicated. It means arrays of two-terminal memories can be stacked in three-dimensional configurations, vastly increasing the amount of information a memory chip might hold. Tour said his lab has also seen promise for making multi-state memories that would further increase their capacity.