Doping of Si nanowires by ion implantation

Silicon nanowires (Si NWs) have generated enormous scientific interest as building blocks for future nanoelectronics. Due to the quasi-one dimensional structure and a high surface to volume ratio of Si NWs controlled doping to change their electrical properties is challenging. Also, in order to understand the doping mechanism various techniques were used to qualify the spatial distribution and electrical activation of dopant atoms in Si. In our previous work strong surface segregation of implanted phosphorus was found after the rapid thermal annealing (RTA). [1] The studies were carried out for relatively thick Si NWs grown by Molecular Beam Epitaxy (MBE) with a diameter of ~100 nm. However, the preferable size for the future logic application is in the range below 20 nm. This work will also discuss the doping behavior of the thin Si NWs with diameters of sub-20 nanometer fabricated by metal-assisted chemical etching. Electrical characterization of the thin NWs was performed by SSRM of the NW cross section. The issues of the doping of such thin NWs by ion implantation and the diameter dependence of the boron activation in the Si NW are discussed.
[1] Xin Ou et al., Nano Letters, 10 (2010) 171.