Mapping of single donors in nano-scale MOSFETs at low temperature

Using low temperature measurements we have been able to identify the influence of only about five donors in the channel the channel of an ultra-scaled MOSFET as the source of an anomalously low room temperature threshold voltage and large sub-threshold slope. Further we observe the influence of these dopants on the low temperature threshold voltage shift as a function of applied back gate voltage. The understanding of this behavior allows us to identify resonant tunneling mediated by a single donor in the channel of a doped channel device and we show that the back gate strongly modifies the tunnel coupling. These results give new insights in dopant transport in ultra-scaled MOSFETs, which is relevant for conventional device characteristics as well as for new dopant-based device architectures.