Silicon is the dominant material in microelectronics and photovoltaics and is probably the best understood semiconductor. However, the optoelectronic properties of nanoscale silicon can be radically different from those of the bulk phase, creating unique opportunities to tailor the material for specific applications. Silicon nanostructures are frequently approached from one of two angles: (i) fundamental investigations aiming to understand and characterize its basic properties; and (ii) development of microelectronics technologies that aim to improve CMOS performance. Both doping and interface effects have been found to critically control the opto-electronic character of nanoscale silicon, leading to the possibility of several new applications. The increasing surface-to-volume ratio makes nanostructures highly sensitive to the nature of the surface terminating groups or to the adjacent embedding matrix. In addition, structural defects at interfaces, such as dangling bonds, are efficient charge carrier recombination centers in both bulk and nanostructured silicon, which requires efficient means of passivation. A prominent example from leading-edge photovoltaic technology is the heterojunction with intrinsic thin layer (HIT) solar cell, which requires passivating tunnel contacts. The development of new technologies will clearly benefit from a deeper insight into surface/interface phenomena. Silicon nanostructures also show a promising potential for biomedical applications and sensing, for which a thorough understanding of the interaction of the silicon interface with various external environments is mandatory. For example, the interface functionality is critical in achieving analyte specificity. By controlling the interface chemistry of free-standing silicon quantum dots (or porous silicon), one can tune the response to different vapors and gases. Similarly, silicon-based microstructures such as ring resonators and cantilevers are opening new opportunities in biomolecular sensing with unprecedented selectivity and sensitivity. In all these applications, the interface effects play a critical role that determines the response of the devices to the targeted analytes. Another issue of interest is the generation of majority carriers in Si nanostructures via conventional impurity doping. Several effects prevent efficient Si doping at the nanoscale: (i) self-purification and dopant deactivation at interfaces, (ii) dopant deactivation due to quantum confinement or band bending from surface states, (iii) the inability to achieve reliably constant dopant levels due to statistical problems (Poisson distribution), (iv) the increasing formation energies of substitutional integration of dopants in the Si lattice and thereby extrusion onto interstitial lattice sites. Since many device concepts are based on pn-junctions their scalability towards single nanometer dimensions is non-trivial, mainly due to doping problems. In order to continue the successful evolution of silicon in established and emerging technologies a “multidimensional” understanding of the doping within nanostructures and on the interface is required. This symposium will bring together researchers from applied and fundamental physics and material science in order to exchange recent experimental and theoretical approaches and results. The scope of the symposium will cover the broad range of theory and modeling, synthesis methods, and device fabrication, as well as measurement and probing technologies.