Design of dopant-induced quantum dot arrays in silicon nanostructures for single-electron transfer

摘要

Randomly distributed dopants in the channel of silicon-on-insulator (SOI) field-effect transistors (FETs) can introduce potential fluctuations that modify the electrical behavior of the device. Furthermore, as device dimensions are scaled down, quantum effects such as the Coulomb blockade and single-electron tunneling strongly influence electron transport through doped Si nanowires. We have previously proved that dopant-induced potential fluctuations essentially act as quantum dots, which confine individual charges and thus provide control over electron transfer down to a single electron per gate voltage cycle. However, because in the conventional doping techniques the position and number of dopants in the channel cannot be known with absolute accuracy, experimental and analytical studies of a variety of conditions for dopant arrays are called for. We have investigated the dc-gate behavior of single-gated SOI FETs with different doping concentrations and channel sizes and our results provide some guidelines for choosing the appropriate conditions to enhance the Coulomb blockade effect. We have also extended our analytical investigation of single-electron transfer in few-quantum-dots arrays. This new analysis suggests that single-electron transfer operation is achievable with high probability in one-dimensional quantum dot arrays with fairly large dispersion of dot sizes, as would be expected for randomly-doped-channel FETs. Even more, this study allows us to discriminate the most favorable quantum dot arrangements, while also giving an insight into the single-electron transfer mechanism in such random systems.