Crystalline material cuts transistor size

MOTOROLA claims to have built the world’s thinnest functional transistor using a new class of material called perovskite. The material should enable electronics engineers to further cut the size of chips.

Transistors three times thinner than existing devices have already been produced.

The most common transistors – field-effect transistors – use a `gate’ to switch current flowing between the transistor’s semiconductor and electrodes off and on. The gate must be separated from the semiconductor by a thin insulating layer.

Gate insulators have been made from silicon dioxide for the past 30 years. But as transistors have become smaller the limit to which silicon dioxide can be thinned has been approached.

Perovskites are a class of crystalline material consisting of a metal atom inside an oxygen octahedron structure. This structure gives it unusual electrical properties. In the lab it can be made by artificially building up one atomic layer at a time resulting in a pure, near-perfect crystal.

Motorola researchers modelled the way individual atoms in perovskite interfaced with silicon crystal semiconductor using computer simulations. This enabled them to engineer a precise match between the two materials to form one single crystal. This crystal has electrical properties ten times better than standard silicon dioxide.

Motorola Labs has grown perovskite on silicon wafers up to 8 inches in diameter, with thicknesses varying only one atomic layer between each wafer.

* www.motorola.com