An all metal nitride nanostructure configuration: Study and exploitation in efficient photo-detection

Abstract

Plasmonic metal and semiconductor hetero-structures in the nanometer regime render outstanding ingredients for efficient photodetection due to their complementary optical properties. While extracting surface plasmon generated hot carriers from such metal-semiconductor Schottky barriers have been reported widely, extraction of carriers generated from the interband transitions in the plasmonic metal nitride has not seen the forefront research yet. Here, we have explored the new aspect of extracting the interband transition generated charge carriers of plasmonic titanium nitride (TiNx) in an all metal nitride based device geometry with tantalum nitride (TaNx) as the base semiconductor matrix. The photoactive component of the device, TiNx/TaNx, shows two strong absorption peaks, one in the UV region and other in the visible region. The later indicates the well-known plasmon excitation of TiNx nanostructures whereas the former is due to its interband transition. The excitonic effect of TaNx further enhances the light absorption and charge carrier generation in the UV region. The fabricated device thus exhibits a substantial photoresponsivity of 42 mA/W and detectivity of 5.6 × 1010 Jones under the UV illumination of wavelength 310 nm. We have also tried to exploit the tunability of plasmon resonance band in plasmonic TiNx and successfully fabricated a device which shows considerable photoresponse in the NIR and UV region as well, thus harvesting both plasmon induced hot carriers and interband transition generated carriers of TiNx in one single device configuration. The overall performance, cost efficiency and large scale integration possibilities make this all nitride detector a promising candidate for real-world applications.