2 December 2011
IQE and Penn State present arsenide/antimonide vertical hetero tunnel FETs
At the 2011 IEDM International Electron Devices Meeting (IEDM) in Washington, DC, USA next week (5-7 December), epiwafer foundry and substrate maker IQE plc of Cardiff, Wales, UK and Pennsylvania State University will present a joint paper on recent key developments in compound semiconductor device technologies for low-voltage transistor applications.
To be presented by Penn State’s Dheeraj Mohata, the paper ‘Demonstration of MOSFET-Like On-Current Performance in Arsenide/Antimonide Tunnel FETs with Staggered Heterojunctions for 300mV Logic Applications’ describes the demonstration experimentally of a vertical hetero tunnel field-effect transistor (HTFET) with a record high drive current (ION) of 190µA/µm and 100µA/µm at VDS=0.75V and 0.3V, respectively.
The research measured, simulated and benchmarked the performance of compound semiconductor based tunnel-FET (TFET) with 40nm strained silicon MOSFET performance for low-voltage (0.3V) logic applications, demonstrating the potential for arsenide/antimonide (As/Sb)-based materials for integration into future ultra-low-voltage electronic devices where high performance and low power consumption is a critical factor.
The tunnel FET is an emerging transistor concept being explored by many groups around the world. In traditional MOSFETs (the building block of digital technology) the transistor channel is turned on by injecting carriers over a gate-controlled p-n junction. This results in a gradual turn-on of the transistor and works well as long as the supply voltage of operation is not reduced too much. In tunnel FETs, the transistor channel is turned on by injecting carriers through a gate-controlled tunnel junction. This results in abrupt turn-on of the transistors, which allows the supply voltage to be reduced and hence significant power saving to be achieved.
The biggest hurdle facing the adoption of tunnel FETs by the mainstream semiconductor industry is that the drive current demonstrated to date is quite low due to limitation of the band-to-band tunneling rate in known semiconductors. However, by carefully selecting the appropriate combination of two different semiconductors and adjusting their composition such that their band alignment results in a staggered configuration, one can significantly increase the tunneling rate and enhance the drive current of the tunnel FET. This has been achieved in the vertical HTFET discussed in the paper and offers the potential to enable a new generation of electronics that can operate in highly energy-constrained environments, says IQE.