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Electrically Tunable, CMOS-Compatible Metamaterial Based on Semiconductor Nanopillars
journal contribution
posted on 2018-10-23, 00:00 authored by Matthew Morea, Kai Zang, Theodore I. Kamins, Mark L. Brongersma, James S. HarrisWith the advent of autonomous vehicles
imminent, a solid-state
approach to beam steering is necessary for more affordable lidar tracking
systems. Capable of dynamic control of light with subwavelength components,
electrically tunable metamaterials show potential in this field as
well as other applications. Here, we demonstrate a nanopillar-based
metamaterial composed of Ge and Al-doped ZnO (AZO), whose optical
properties can be modulated by the field effect and whose fabrication
process is compatible with complementary metal-oxide-semiconductor
(CMOS) technology. From reflectance spectra, wavelength shifts up
to 240 nm of the optical resonances are measured in our fabricated
device with gate biases from −4 to 4 V. A high differential
reflectance of more than 40% in this voltage range is experimentally
shown. Then, through an effective medium approximation, we can describe
the nanopillar array as a macroscopic metamaterial and calculate the
phase shift of this device. With optimization of the nanopillar parameters,
a large phase modulation approaching 270° is possible according
to simulations, which is promising for beam steering applications.
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voltage rangereflectance spectrananopillar arrayphase shift4 VSemiconductor Nanopillarsmacroscopic metamaterialphase modulationwavelength shiftsgate biasestunable metamaterials showbeam steeringfabrication processnanopillar parametersnanopillar-based metamaterialmedium approximationAl-doped ZnOCMOS-Compatible Metamaterialsubwavelength componentsfield effectAZOdeviceElectrically Tunable240 nmbeam steering applications