Move aside, flat computer chips of the past — researchers from Purdue and Harvard universities have developed a new type of transistor made from a material that could replace silicon and offer a 3D structure. This development could enable engineers to build faster, more compact, and efficient integrated circuits and lighter laptops that generate less heat than today’s.
The transistors contain tiny nanowires made not of silicon, like conventional transistors, but from a material called indium-gallium-arsenide. To create the transistor, researchers used a “top-down” method, which is akin to industrial processes to precisely etch and position components in transistors. The approach is compatible with conventional manufacturing processes, offering promise for adoption by industry.
Transistors contain critical components called gates, which enable the devices to switch on and off and to direct the flow of electrical current. In today's chips, the length of these gates is about 45 nanometers, or billionths of a meter. However, in 2012, industry will introduce silicon-based 3-D transistors having a gate length of 22 nanometers.
The 3-D design is critical because the 22-nanometer gate lengths will not work in a flat design. The nanowires are coated with a "dielectric," which acts as a gate. Engineers are working to develop transistors that use even smaller gate lengths, 14 nanometers, by 2015. These smaller transistors will require finding a new type of insulating layer essential for the devices to switch off. One potential solution is to replace silicon dioxide with materials that have a higher insulating value, or “dielectric constant,” such as hafnium dioxide or aluminum oxide.
Also: Metal emitter structures in a class of developmental InP-based high-speed heterojunction bipolar transistors (HBTs) were redesigned to have T-shaped cross-sections.
