Forward-looking: The billions of transistors hidden within a single CPU are manufactured to execute just one specific function. A team of Viennese scientists, however, aims to introduce programmability features at the most fundamental hardware level of computing technology.
Researchers at the Austrian university TU Wien have developed a novel transistor technology known as Reconfigurable Field Effect Transistors (RFET). Traditional transistors are designed to perform predetermined logical functions, while RFETs are used to build circuits with functions that can be programmed on the go.
RFETs could represent a significant breakthrough in electronic circuit and chip design technology, the researchers explained. Programmable transistors use the same materials employed by the semiconductor industry, silicon and germanium, and they could provide significant improvements in power consumption and energy efficiency.
Traditional transistor development involves chemical doping, a technique used to "contaminate" the semiconductor material with foreign atoms. The doping process determines the direction in which electric current can flow and cannot be changed once the transistor is created. RFETs replace chemical doping with electrostatic doping, a new method that doesn't permanently alter the chemical configuration of the semiconductor material.
Once the "complex and costly" process of chemical doping is replaced by electric fields, the transistors can be dynamically reconfigured to perform different logic operations.
TU Wien professor Walter M. Weber stated that the reconfiguration works at the "fundamental switching units," rather than routing information to fixed functional units. This approach is "highly promising" for building future reconfigurable computing and AI applications, Weber added.
The researchers developed the basic RFET technology in 2021, and they have now demonstrated that reprogrammable transistors can be used to construct all the basic logic circuits in a chip. The recently published study showcases an inverter, NAND/NOR, and XOR/XNOR gates, which are capable of dynamically switching their operation mode at runtime.
The additional gate electrodes needed for electrostatic doping occupy space, which means RFETs aren't as small as standard CMOS transistors. The new programmable transistors are unlikely to replace fixed transistors anytime soon, but they could coexist and power certain computing applications where flexibility is paramount.
The reconfigurable nature of RFETs can reduce the total number of transistors needed for logic circuitry, the researchers explained. Fewer transistors mean less space is required to build chips, and power consumption is reduced as well. A single circuit could provide multiple functionalities by switching the polarity of individual transistors or the entire circuit.
