Highly Stable Plasmon Induced Hot Hole Transfer into Silicon via a SrTiO₃ Passivation Interface

Extracting plasmon-induced hot carriers over a metal–semiconductor Schottky barrier enables photodetection below the semiconductor bandgap energy. However, interfacial carrier recombination hinders the efficiency and stability of this process, severely limiting its implementation in telecommunication. This study proposes and demonstrates the use of epitaxially grown lattice-matched SrTiO₃ for interfacial passivation of silicon-based plasmonic Schottky devices. The devices are activated by an electrical soft-breakdown of the interfacial SrTiO₃ layer, resulting in reproducible rectified Schottky characteristics. The transition to a low resistance state of the SrTiO₃ layer boosts the extraction efficiency of hot holes upon resonant plasmonic excitation, giving rise to a two orders of magnitude higher photocurrent compared to devices with a native oxide layer. Photoresponse, tunability, and barrier height studies under reverse biases as high as 100 V present superior stability with the incorporation of the SrTiO₃ layer. The investigation paves the way toward plasmon-induced photodetection for practical applications including those under challenging operating conditions.