Jeongeun Mo1,2,Dasom Wang1,Ji-Hun Kang3,Jeong Min Baik2,Won Jun Choi1
Korea Institute of Science and Technology1,Sungkyunkwan University2,Kongju National University3
Jeongeun Mo1,2,Dasom Wang1,Ji-Hun Kang3,Jeong Min Baik2,Won Jun Choi1
Korea Institute of Science and Technology1,Sungkyunkwan University2,Kongju National University3
In recent years, the demand for high-performance infrared image sensors has increased significantly in various fields, including military applications, medical imaging, and Advanced Driving Assistance Systems (ADAS). Microbolometers, which are cooler-free infrared image sensors, have gained popularity due to their affordability and convenience. However, to enhance the performance of microbolometers, it is crucial to achieve high responsivity and detectivity. Effective infrared (IR) absorption is essential for microbolometers to efficiently transfer heat to the thermistor layer and achieve high responsivity (R<sub>v</sub> = α<b>η</b>I<sub>b</sub> R<sub>0</sub>/G(1 + ω<sup>2</sup>τ<sup>2</sup>)<sup>(1/2)</sup>). To address this requirement, we applied a meta-structured IR absorber to enhance the IR absorptance of microbolometers.<br/>In this study, we employed an alternating metal-dielectric multilayer films with different refractive index as the IR absorbing medium. A periodic circular structure is introduced to multilayer films for higher absorptance. This structure has been designed to decrease total volume of IR absorbing medium in order to get lower thermal mass so that heat can easily transfer to the thermistor layer. FDTD simulation is conducted to compare the dependence of different sizes of periodic circles and intervals on absorptance of meta-structured multilayered absorber. This result revealed significant improvement in the absorptance of incident light in LWIR region (8-14um), which is commonly used for object detection. For experimental demonstration, IR absorber is deposited by electron beam evaporator based on reported previous research.<sup> </sup>The experimental results confirmed that the meta-structured IR absorber exhibited higher absorptance compared to the non-meta-structured counterpart. Consequently, we expect that the application of meta-structured IR absorber to microbolometers will facilitate the temperature increase of the thermistor material, leading to a notable improvement in responsivity. In conclusion, the presented research will give an idea of increasing responsivity of microbolometer with drawing up absorptance of IR absorber with meta-structure.