  Using Ensemble Monte Carlo simulations the photocurrent in a 500nm long
strained [110] silicon nanowire with diameter of 3.1 nm is investigated. It was
observed that a phototransistor based on this nanowire can have responsivities
in the order of 21.3 mA/W for an input light wavelength of 532 nm and intensity
of 0.25-2.5 kW/cm2. The super-unity slope of 1.2 in photo conductance versus
input light intensity suggests that the nanowire has a photoconductive gain and
highlights its advantage over germanium nanowires with sub-unity slope (0.77).
The generated photocurrents are in the 0.1 nA-1 nA range. Density Functional
Theory (DFT) and Tight Binding (TB) methods were used for strain application
and band structure calculation, respectively. Both longitudinal acoustic and
optical phonons were included in the calculation of the carrier-phonon
scattering events, which showed a two-order of magnitude stronger role for
longitudinal optical phonons.
