MoS2 and TiN surface plasmon polaritons: A new frontier for PIN photodetector design, compared to gold and silver, and their temperature response

Abstract

This paper examines the spectral performance of Surface Plasmon Polariton (SPP)-enhanced photodetector arrays based on Germanium (Ge), Silicon (Si), Indium Phosphide (InP), and Gallium Arsenide (GaAs) substrates. The performance of devices using gold (Au) and silver (Ag) as reference plasmonic materials is systematically compared with proposed alternatives, including molybdenum disulfide (MoS₂) and titanium nitride (TiN). Across all semiconductor platforms, Au-based SPP arrays demonstrated significantly better performance in both peak current density and responsivity than their Ag, MoS₂, and TiN counterparts, often by factors of 1.5 to over 2. The proposed materials generally showed silver as the next highest performer, followed by MoS₂ and TiN. While alternative plasmonic materials, such as MoS₂ and TiN, may offer benefits like lower cost or easier integration compared to silver, the absolute current generation and responsivity are notably lower than those of silver in the studied configurations. The highest performance was observed in the Ge-pin photodetector, which achieved 25 mA/cm² with gold, compared to 13 mA/cm² with silver, 12.5 mA/cm² with MoS₂, and 12 mA/cm² with TiN. Its peak responsivity reaches approximately 250 A/W with gold, 130 A/W with silver, 125 A/W with MoS₂, and 115 A/W with TiN. Results showed that Ge outperformed all other tested photodetectors, while the Silver SPP performed similarly to MoS₂ and TiN. Our study explores the effect of temperature on our proposed materials and SPPs. The findings demonstrate that higher temperatures negatively impact the efficiency of these plasmonic devices, likely due to increased carrier scattering and reduced semiconductor performance.