Energy Redistribution Due to Parasitic Absorption in the Cr Adhesion Layer of an Ag Grating/InAs Quantum Wire Multilayer Heterostructure

Abstract

In recent years, quantum wire infrared photodetectors have attracted extensive attention due to their high optoelectronic conversion efficiency arising from quantum confinement effects. Although metal gratings are widely employed to enhance light absorption, the influence mechanism of their parasitic absorption on device performance upon the introduction of a Cr adhesion layer to ensure mechanical stability remains unclear. In this work, a Cr adhesion layer is introduced into an Ag grating/InAs quantum wire multilayer heterostructure. Through frequency-domain simulations, the optical absorption characteristics are analyzed, and the energy redistribution mechanism of the Cr layer is revealed. The results show that after introducing a 10 nm Cr layer, the total absorptance of the device increases by 3.07% and 9.22% at 1.9 μm and 3.6 μm, respectively. However, the Cr layer dissipates 85.49% and 52.83% of the incident energy, compressing the effective absorption of the quantum wire active region to below 1%. This "increase in total absorption, yet loss in active-region absorption" effect originates from the interception and absorption of reflected energy by the Cr layer, which shifts the primary site of energy dissipation from the Ag grating to the Cr layer. This study provides quantitative criteria and theoretical guidance for the design of adhesion layers in quantum wire infrared photodetectors and similar multilayer plasmonic optoelectronic devices.