High Quantum Efficiency Nanopillar Photodiodes Overcoming the Diffraction Limit of Light

Abstract

InAs1-xSbx nanowires have recently attracted interest for infrared sensing applications due to the small bandgap and high thermal conductivity. However, previous reports on nanowire-based infrared sensors required low operating temperatures in order to mitigate the high dark current and have shown poor sensitivities resulting from reduced light coupling efficiency beyond the diffraction limit. Here, InAsSb nanopillar photodiodes with high quantum efficiency are achieved by partially coating the nanopillar with metal that excites localized surface plasmon resonances, leading to quantum efficiencies of ∼29% at 2390 nm. These high quantum efficiency nanopillar photodiodes, with 180 nm diameters and 1000 nm heights, allow operation at temperatures as high as 220 K and exhibit a detection wavelength up to 3000 nm, well beyond the diffraction limit. The InAsSb nanopillars are grown on low cost GaAs (111)B substrates using an InAs buffer layer, making our device architecture a promising path toward low-cost infrared focal plane arrays with high operating temperature.

Nanostructured Materials and Architectures for Advanced Infrared Photodetection

“…For 3D nanostructured photodetectors, specific SPs structures are needed to fit the light coupling to nanostructures beyond planar films. Recently, Lee et al reported a partial metal cover that accommodate near‐field enhancements to the photodetector based on InAsSb nanopillar (NP) arrays (Figure c–e) . As mentioned earlier, NW or NP based photodetectors exhibit much lower dark currents compared to planar devices.…”

“…e) The photoresponse spectra of the photodetector, the peak at ≈2390 nm is ascribed to SPs induced near‐field enhancement. Reproduced with permission . Copyright 2016, American Chemical Society.…”

Circular Polarization Discrimination Enhanced by Anisotropic Media

“…Since compact circular‐polarization‐discriminative devices are highly desired for infrared detection, we investigate the integration of an InAsSb nanowire array with an asymmetric metamaterial. An InAsSb nanowire array is a promising candidate for infrared detection [ 41,48–50 ] because of the tunable band gap, the heteroepitaxial growth, and the release of lattice mismatch strain through radial expansion instead of defect creation. [ 51–53 ] The relative composition of As and Sb in the InAs 1‐ x Sb x nanowires is chosen to be 0.4 and 0.6 for mid‐wavelength to long‐wavelength infrared detection.…”

InAs/InAsP Core/shell Nanowire Photodiode on a Si Substrate

“…The stronger photoresponse at λ = 780 nm may be from the higher absorption attributed by the tightly confined mode on top of the NW supported by the LSP resonance at the edge of the metal cap. 25 The inset shows the detector has a linear photoresponse up to 4 mW at λ = 1310 nm under 0 V. The infrared photoresponse and the linearly increase photovoltaic current at 0 V from the detector suggests the trap states at the InAs/Si heterojunction does not limit the flow of the photocurrent. The photogenerated electrons are collected from the InAs NW top contact and the holes from Si substrate can overcome a small valance band barrier into the InAs NW.…”

“…In addition our didoes show a comparable photocurrent level compared to the reported InAs NW detector with similar NW height. 30 We expect an increased absorption efficiency of the InAs/InAsP NW array detector by appropriate optical design of the NW length and diameter 25 and improving the growth yield to form ordered NW array.…”