Modifying the electronic properties of nano-structures using strain

Abstract

We used density-functional theory based Non equilibrium green function simulations to study the effects of strain and quantum confinement on the electronic properties of Germanium & Silicon NWs along the [110] direction, such as the energy gap and the effective masses of the electron and hole. The diameters of the NWs being studied in a range of 3-20 Å. On basis of our calculation we conclude that the Ge [110] NWs possess a direct band gap, while Si [110] NWs possess indirect band gap at nanoscale. The band gap is almost a linear function of strain when the diameter of Ge NWs D < 10 Å while shows parabolic behaviour for, D > 15 Å; & for Si it is linear in behaviour. On doping silicon wire we found that the bandgap shows parabolic behaviour for change in strain. We also concluded that the band gap and the effective masses of charge carries (i.e. electron & hole) changes by applying the strain to the NWs. Our results suggested that strain can be used to tune the ba nd structures of NWs, which may help in de sign of future nanoelectronic devices.