Abstract
We demonstrate the use of plasmonic effects to boost the near-infrared sensitivity of metal-semiconductor-metal detectors. Plasmon-enhanced photodetection is achieved by properly optimizing Au interdigitated electrodes, micro-fabricated on Ge, a semiconductor that features a strong near IR absorption. Finite-difference time-domain simulations, photocurrent experiments and Fourier-transform IR spectroscopy are performed to validate how a relatively simple tuning of the contact geometry allows for an enhancement of the response of the device adapting it to the specific detection needs. A 2-fold gain factor in the Ge absorption characteristics is experimentally demonstrated at 1.4 µm, highlighting the potential of this approach for optoelectronic and sensing applications.
Highlights
Silicon-based metal-semiconductor-metal (MSM) photodetectors have become important assets in modern optoelectronics and can be applied in a wide wavelength range
Ge is a material of interest for light emission applications because its direct gap is only 0.140 eV above the fundamental indirect gap at 0.66 eV [4,5,6]
Compared to many direct gap III-V semiconductors, Ge offers poor light emission efficiency because the electrons are promoted to the local conduction band minimum at the Γ point, they quickly scatter into the L minimum and the non-radiative transitions are the dominant recombination mechanisms at room temperature [7]
Summary
Silicon-based metal-semiconductor-metal (MSM) photodetectors have become important assets in modern optoelectronics and can be applied in a wide wavelength range. Finite-difference time-domain simulations, photocurrent experiments and Fourier-transform IR spectroscopy are performed to validate how a relatively simple tuning of the contact geometry allows for an enhancement of the response of the device adapting it to the specific detection needs.
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