  Low threshold detectors with single-electron excitation sensitivity to
nuclear recoil events in solid-state detectors are also sensitive to the
crystalline structure of the target and, therefore, to the recoil direction via
the anisotropic energy threshold for defect creation in the detector material.
We investigate this effect and the resulting daily and annual modulation of the
observable event rate for dark matter mass range from 0.2 to 5 GeV/c$^{2}$ in a
silicon detector. We show that the directional dependence of the threshold
energy and the motion of the laboratory result in modulation of the event rate
which can be utilized to enhance the sensitivity of the experiment. We
demonstrate that the spin-independent interaction rate in silicon is
significant for both high and low dark matter masses. For low-mass dark matter,
we show that the average interaction rate in silicon is larger than germanium,
making silicon an important target for identifying dark matter from
backgrounds. We find 8 and 12 hours periodicity in the time series of event
rates for silicon detector due to the 45-degree symmetry in the silicon crystal
structure.
