The Effect of Bending Deformation on Charge Transport and Electron Effective Mass of p-doped GaAs Nanowires

Övrig text i vetenskaplig tidskrift, 2019

The crystal and electronic structure of semiconductor nanowire systems have shown sensitive response to mechanical strain, enabling novel and improved electrical, and optoelectrical properties in nanowires by strain engineering. Here, the response of current–voltage (I–V) characteristics and band structure of individual p-doped GaAs nanowires to bending deformation is studied by in situ electron microscopy combined with theoretical simulations. The I–V characteristics of the nanowire change from linear to nonlinear as bending deformation is applied. The nonlinearity increases with strain. As opposed to the case of uniaxial strain in GaAs, the bending deformation does not give rise to a change in the band gap of GaAs nanowire according to in situ electron energy loss spectroscopy (EELS) measurements. Instead, the response to bending deformation can be explained by strain induced valence band shift, which results in an energy barrier for charge carrier transport along the nanowire. Moreover, the electron effective mass decreases as the strain changes from compressive to tensile across the GaAs nanowire in the bent region. Results from this study shed light on the complex interplay between lattice strain, band structure, and charge transport in semiconductor nanomaterials.