Purdue University engineers have developed a way that the millions of tiny switches used to process information — called transistors — could also store that information as one device. The method, detailed in a paper published in Nature Electronics, accomplishes this by solving another problem: combining a transistor with higher-performing memory technology than is used in most computers, called ferroelectric RAM.
The material, alpha indium selenide, not only has ferroelectric properties, but also addresses the issue of a conventional ferroelectric material usually acting as an insulator rather than a semiconductor due to a so-called wide “band gap,” which means that electricity cannot pass through and no computing happens. Alpha indium selenide has a much smaller band gap, making it possible for the material to be a semiconductor without losing ferroelectric properties.
In the past, researchers hadn’t been able to build a high-performance ferroelectric tunneling junction because its wide band gap made the material too thick for electrical current to pass through. Since alpha indium selenide has a much smaller band gap, the material can be just 10 nanometers thick, allowing more current to flow through it. More current allows a device area to scale down to several nanometers, making chips more dense and energy efficient, Ye said. A thinner material — even down to an atomic layer thick — also means that the electrodes on either side of a tunneling junction can be much smaller, which would be useful for building circuits that mimic networks in the human brain.
Paper: Mengwei Si, Atanu K. Saha, Shengjie Gao, Gang Qiu, Jingkai Qin, Yuqin Duan, Jie Jian, Chang Niu, Haiyan Wang, Wenzhuo Wu, Sumeet K. Gupta, Peide D. Ye. A ferroelectric semiconductor field-effect transistor. Nature Electronics, 2019; DOI: 10.1038/s41928-019-0338-7