Effect of twin boundaries and structural polytypes on electron transport in GaAs

As-grown GaAs nanowires often possess high density of twin boundaries and stacking faults, which serve as scattering planes for electrons. Here, using density functional theory and Green's function method, we demonstrate that the planar faults can significantly alter the transport properties depending on different planar defects and in-plane wavevector of the electronic state. Conductance eigenchannel analysis was applied to reveal the microscopic mechanism of electron scattering. A formalism is developed to estimate the reduction of the electron and hole mobilities due to planar faults and structural polytypes, based on quantum transmission coefficients computed in phase-coherent transport calculations. For twin spacing of 2.4 nm, electron mobility and hole mobility were predicted to be 3000 cm2/V/s and 500 cm2/V/s, respectively. The findings highlight the necessity of removing twins for high-performance nanowire solar cells.