Broad spectral response to photon energy unlimited by Schottky barrier from NiSi/Si junction
Journal
Optics and Laser Technology
Journal Volume
166
Date Issued
2023-11-01
Author(s)
Sun, Ruei Lien
Lai, Hsin Han
Su, Zih Chun
Dong, Yao Han
Chen, Bo Heng
Sinha, Deepali
Syu, Hong Jhang
Abstract
Recent advances in plasmonic absorption devices offer a novel approach for extending the range of silicon light detection. This is achieved by exploiting the Schottky interface energy barrier, which overcomes the limitation of the 1.12 eV photon energy conversion imposed by the silicon intrinsic bandgap. Internal photoemission has been widely accepted as the primary emission mechanism, which is mostly limited by the Schottky barrier height. However, we have discovered that carriers with energy lower than the Schottky barrier can generate electrical responses through the photothermal effect, breaking this restriction. In this study, we closely investigate two forms of photoresponses, namely photoelectric and photothermal, on a NiSi thin film Schottky photodetector, considering various factors such as temperature, applied bias, incident power, and wavelength regime. Without photothermal assistance, the device achieves a responsivity of 0.41 mA/W to a 1550 nm laser. Under bias-driven conditions, highly energized hot carriers generate a 2.18 μA photoelectric response, while a 0.861 μA photothermal response is simultaneously observed under 6 mW 1550 nm laser illumination. Through systematic investigation, we advance the mechanism of both responses by combining the hot carrier model and the Schottky barrier diagram. Finally, we experimentally obtain a 4.85 μA sheer photothermal response to a 0.475 mW 4-μm wavelength signal with 10.21 mA/W responsivity. It is expected that the device will also show responses to longer wavelengths.
Subjects
Hot carrier | Infrared | Photodetector | Photothermal | Plasmonic | Schottky barrier
SDGs
Type
journal article