  Reconfigurable metamaterial-based apertures can play a unique role in both
imaging and in beam-forming applications, where current technology relies
mostly on the fabrication and integration of large detector or antenna arrays.
Here, we report the experimental demonstration of a voltage-controlled,
silicon-based electromagnetic metamaterial operating in the W-band (75-110
GHz). In this composite semiconductor metamaterial, patterned gold metamaterial
elements serve both to manage electromagnetic wave propagation while
simultaneously acting as electrical Schottky contacts that control the local
conductivity of the semiconductor substrate. The active device layers consist
of a patterned metal on a 2-{\mu}m-thick n-doped silicon layer, adhesively
bonded to a transparent Pyrex wafer. The transmittance of the composite
metamaterial can be modulated over a given frequency band as a function of bias
voltage. We demonstrate a quantitative understanding of the composite device
through the application of numerical approaches that simultaneously treat the
semiconductor junction physics as well as wave propagation.
