Single donor ionization energies in a nanoscale CMOS channel

TL;DR

This study demonstrates that a single arsenic dopant significantly influences the behavior of nanoscale CMOS transistors at room temperature, with its ionization energy being strongly affected by nearby dielectric interfaces, impacting device variability.

Contribution

It provides direct measurement of single dopant ionization energies at room temperature and reveals how dielectric environment modifies these energies in nanoscale CMOS devices.

Findings

Single arsenic dopant affects off-state transistor behavior at room temperature.

Ionization energy of arsenic dopant is enhanced from 54meV to 108meV near buried oxide.

Results explain variability in ultra-scaled transistors and suggest quantum functionalities integration.

Abstract

One consequence of the continued downwards scaling of transistors is the reliance on only a few discrete atoms to dope the channel, and random fluctuations of the number of these dopants is already a major issue in the microelectonics industry. While single-dopant signatures have been observed at low temperature, studying the impact of only one dopant up to room temperature requires extremely small lengths. Here, we show that a single arsenic dopant dramatically affects the off-state behavior of an advanced microelectronics field effect transistor (FET) at room temperature. Furthermore, the ionization energy of this dopant should be profoundly modified by the close proximity of materials with a different dielectric constant than the host semiconductor. We measure a strong enhancement, from 54meV to 108meV, of the ionization energy of an arsenic atom located near the buried oxide. This enhancement is responsible for the large current below threshold at room temperature and therefore explains the large variability in these ultra-scaled transistors. The results also suggest a path to incorporating quantum functionalities into silicon CMOS devices through manipulation of single donor orbitals.