Enhanced Dielectric Environment Sensitivity of Surface Plasmon-Polariton in the Surface-Barrier Heterostructures Based on Corrugated Thin Metal Films with Quasi-Anticorrelated Interfaces

Abstract

A new approach to the formation of a 1D planar periodicity on the front of a plasmonic photodetector based on Schottky barrier is proposed. It allows forming a 1D planar periodicity with corrugation at the “metal/environment” interface by laser interference lithography using embedded chalcogenide wires, whereas the “metal/semiconductor” interface is flat that leads to reducing of surface recombination losses at Shottky barrier in contrary to the conventional technology for forming corrugated metal films on the semiconductor surface requiring chemical etching of the semiconductor substrate. In this case, the metal film interfaces are quasi-anticorrelated as opposed to correlated ones in the conventional technology. It has been theoretically predicted that the polarization sensitivity (T p/T s) strongly depends on the cross-sectional shape of chalcogenide wires and reaches a value of 8. Furthermore, it was theoretically found that the maximum sensitivity of the signal intensity on the environment refractive index is three times larger than for an equivalent structure obtained by conventional technology. Comparison of experimental data for the photocurrent in the case of two types of correlation between metal film interfaces demonstrates good agreement with numerical simulations.

Aluminum-Based Plasmonic Photodetector for Sensing Applications

“…A clearly pronounced plasmonic maximum is observed around θres = 15°, corresponding to SPP excitation. The shape of the resonance curve for such structures is closer to a Fano shape, as shown in [20] for gold gratings with a similar groove shape. Figure 6a (Curve 1) shows the dependence of the maximum light absorption in the silicon substrate (max A(θ)) on d for the simulated structure.…”

“…For the investigated PPPDs with the optimal parameters of the Al grating, we obtained a value of Ip/Is = 8, an FWHM of the photocurrent spectrum from 50 to 100 nm, and sensitivity at the resonance maximum of Iph = 0.04-0.06 A/W. The obtained PPPD characteristics are comparable to the best characteristics for PPPDs with gold gratings [20]. These practical results open up prospects for replacing gold in the production of PPPD with aluminum, which significantly lowers their cost.…”

“…For fabricating PPPDs, a pre-made p-n junction on n-Si (111) with a burial depth of 100 nm and 25/250 nm Ti/Ni ohmic rear contacts were used. The necessary periodic relief structures (gratings) on the silicon surface were created using interference lithography with thermally deposited chalcogenide photoresists in a vacuum [20]. A particular feature of this technology, compared to the standard one where the grating is etched into the semiconductor, is the profiling of the metallic plasmon-carrying Al film only.…”

“…This maintains a flat metal/semiconductor interface with low recombination of the photo-generated carriers. Such a PPPD has a simpler construction and good resonant properties [20].…”

“…However, the presence of a corrugated interface at the Schottky junction contributes to enhanced carrier recombination and scattering, leading to the attenuation of the useful signal. In this regard, PPPD designs with a flat metal-semiconductor interface have been proposed, with the grating relief formed on the outer side of the plasmon-carrying metallic film [20].…”