MIT unveils ‘world’s smallest’ indium gallium arsenide transistor

While transistors usually consist of three tightly packed electrodes: the gate, the source and the drain, with the gate controlling the flow of electrons between the other two, the researchers found a way to allow the gate to self align itself between the other two electrodes. To do this they first grew a thin layer of the material using molecular beam epitaxy, a process in which evaporated atoms of indium, gallium and arsenic react with each other within a vacuum to form a single crystal compound. They then deposited a layer of molybdenum as the source and drained the contact metal, before drawing an extremely fine pattern onto this substrate using a focused beam of electrons - a technique known as electron beam lithography. Unwanted areas of material were then etched away and the gate oxide was deposited onto the tiny gap. Finally, evaporated molybdenum was fired at the surface, where it formed the gate, tightly squeezed between the two other electrodes. The next step for the team is to work on further improving the electrical performance - and hence the speed - of the transistor by eliminating unwanted resistance within the device. Once they have achieved this, the researchers will attempt to further shrink the device, with the ultimate aim of reducing the size of their transistor to below 10nm in gate length.