Steep switch with hybrid operation mechanism for performance improvement (invited)

Tunnel FET (TFET) has attracted much attention as one of promising candidates of MOSFET for low power applications due to its capability of sub-60mV/dec subthreshold slope (SS) at room temperature [1]. It has a gated p-i-n structure switched by band-to-band tunneling (BTBT) mechanism. However, it is difficult to form abrupt source doping profile in the experiments for sharp band bending at the junction, resulting in relatively large SS of experimental demonstrations compared with ideally theoretical expectations. Another critical issue is that the on current (ION) is relatively low, especially for silicon-based TFET. The resulting issues of low ION, including large intrinsic delay and low gain, may also limit its applications. In recent years, most of TFET researchers focused on the methods for SS reduction and the I
_ON
enhancement, including adoption of the small-bandgap materials, heterojunction [2], nanowire structure [3] and advanced annealing technology [4], etc. Mechanism engineering is focused in our research work as a different possible way to solve the TFET issues, not only improving I
_ON
and SS values, but also enhancing comprehensive properties in terms of reduced Miller capacitance [5], immune to the super-linear onset of output characteristics [6] and reduced noise [7], etc.