Dual Band Thin Film Infrared Detector Design and Performance Improvement using Plasmonic Nanostructure

Abstract A new dual band thin film metal-semiconductor-metal infrared photodetector base on InGaAs for wavelength of 1.1–1.7 µm and InSb for wavelength of 3–5 µm is proposed and investigated numerically. One major problem of thin film photodetectors is low quantum efficiency that originates from low optical absorption. The quantum efficiency of proposed structure is improved by locating the array of optimized aluminum nanostructure (Al-NS) between the InGaAs and InSb layers. Using optimized Al-NS between the stack of InGaAs and InSb (InSb/Al-NS/InGaAs) results in plasmon excitation inside the photosensitive layers and so, higher photocarrier generation. Moreover, locating zinc oxide nanorode as an antireflection coating on top of detector reduces the incident light reflection in both spectrum of 1.1–1.7 µm and 3–5 µm. The finite different time domain method is used to investigated the optical properties of proposed structure and optimize the structure. According to the simulation results, designed structure gives rise to 108.1%, 110% and 320% light absorption enhancement at wavelength of 1.33 µm, 1.55 µm and 4 µm, respectively compared to reference conventional structure.