Plasmonic Near-Infrared Photoconductor Based on Hot Hole Collection in the Metal-Semiconductor-Metal Junction

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Plasmonic resonance enables hot carrier generation, overcoming semiconductor band gap limitations for photodetection.
• Existing metal-semiconductor (MS) junction photodetectors have low responsivity and are limited by conventional semiconductor platforms.
• Hot carrier photodetection strategies are an active research area for advanced optoelectronic applications.

Purpose of the Study:

• To propose and demonstrate a new metal-semiconductor-metal (MSM) architecture for efficient infrared photodetection.
• To leverage plasmonic resonance and hot carrier emission in a silicon-based platform.
• To achieve high photocurrent responsivity beyond the cut-off wavelength of silicon.

Main Methods:

• Fabrication of a silicon-based MSM junction with coplanar interdigitated electrodes.
• Utilizing a random gold/silicon (Au/Si) nanoholes structure for plasmonic absorption and hot-spot enrichment.
• Employing a back-to-back Schottky diode configuration for efficient hot hole collection.
• Investigating the photoconductance gain mechanism for enhanced photodetection.

Main Results:

• The MSM device demonstrated efficient hot hole collection at infrared wavelengths.
• The photoelectric response extended significantly beyond silicon's cut-off wavelength.
• The interdigitated electrode design resulted in a very high photoconductive gain.
• Photocurrent responsivity reached several A/W, over 1000 times higher than existing hot carrier strategies.

Conclusions:

• The proposed MSM architecture effectively utilizes plasmonic hot carriers for high-performance infrared photodetection.
• This approach overcomes the limitations of traditional semiconductor photodiodes and single MS junction devices.
• The device shows great promise for advanced infrared sensing applications requiring high sensitivity and broad spectral response.