NOEL

High-efficiency photo-electron conversion devices


 

High-efficiency photo-electron conversion devices

Semiconductor processes and nanofabrication

Characterizations and applications of nanomaterials

Light harvesting and light extraction

Optical analysis techniques

Eco-friendly devices and sensors

 

 


 

 


 

Silicon-based broadband antenna for high responsivity and polarization-insensitive photodetection at telecommunication wavelengths

Although the concept of using local surface plasmon resonance based nanoantenna for photodetection well below the semiconductor band edge has been demonstrated previously, the nature of local surface plasmon resonance based devices cannot meet many requirements of photodetection applications. Here we propose the concept of deep-trench/thinmetal (DTTM) active antenna that take advantage of surface plasmon resonance phenomena, three-dimensional cavity effects, and large-area metal/semiconductor junctions to effectively generate and collect hot electrons arising from plasmon decay and, thereby, increase photocurrent. The DTTM-based devices exhibited superior photoelectron conversion ability and high degrees of detection linearity under infrared light of both low and high intensity. Therefore, these DTTM-based devices have the attractive properties of high responsivity, extremely low power consumption, and polarization-insensitive detection over a broad bandwidth, suggesting great potential for use in photodetection and on-chip Si photonics in many applications of telecommunication fields.


A plasmonic device possessing the DTTM active antenna structure for photodetection well below the semiconductor band edge. (a) Energy band diagram for plasmonically driven ‘hot’ electrons over a metal–semiconductor Schottky barrier. (b) Schematic representation of the electrical measurement set-up and proposed DTTM active antenna structure on a Si-based device. (c) Top-view and cross-sectional scanning electron microscopy images of DTTM structures on Si substrates.


Optical behaviour of nanoantenna (Lrod¼140 nm; Wrod¼50 nm) and DTTM (H07P14) arrays
simulated using the 3D-FDTD method to investigate the effects of incident light with different polarization states and distinct wavelengths on the antennas. (a) For x-polarized light, the nanoantenna provided large electric field intensities at 1,420 nm, but the near-field intensities decreased dramatically as the wavelength moved away from the LSPR wavelength. (b) For y-polarized light, the nanoantenna did not reveal any plasmonic responses at wavelengths of 1,310, 1,420 or 1,550 nm. (c) The DTTM active antenna displayed high electric field intensities around the antenna structures at distinct wavelengths, regardless of the polarization of the incident light.

 
 
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