“We have entered an era where new chip technologies require making trade-offs between power, performance, cost and area. And these trade-offs will be considered separately for different application domains,” said Nadine Collaert, a distinguished member of imec’s technical staff. “TFETs will most probably find their place in the ultra low-power segment. Many applications in the future require transistors to work at low power and low voltage, such as IoT applications.
While MOSFETs introduce carriers from the source into the conducting channel by thermal injection, a TFET works through band-to-band tunnelling. In this way, sub threshold swings of less than 60mV/dec may be possible; in turn, allowing them to operate from supply voltages of less than 0.5V.
The imec device is an InGaAs homojunction TFET. It shows a minimum sub-threshold swing of 54mV/dec at 100pA/µm and the researchers say the sub-threshold swing remains less than 60mV/dec over 1.5 orders of magnitude of current at room temperature. The equivalent oxide thickness of the device is 0.8nm, which imec says plays a major role in achieving the desired sub 60 mV/dec performance.