Modeling of the Substrate Influence on Multielement THz Detector Operation

Abstract

The development of THz multielement uncooled imagers based on focal plane arrays (FPAs) requires an optimization of the system parameters to achieve a homogeneous sensitivity of the array elements. Results of numerical simulation of the eight-element linear array of planar antennas with detecting elements, on a substrate of finite dimensions are presented. We establish how the substrate thickness h and the relative permittivity ε r influence antenna pattern and antenna-detector matching for each element. We show that the antenna pattern depends on the detector position more than the antennadetector impedance matching. The gain of array elements, the antenna-detector matching, and the homogeneity of the detector sensitivity can be simultaneously optimized by the proper choice of the substrate thickness h and the relative permittivity ε r . We show that multielement systems with large substrate thickness and high relative permittivity are not suitable for the imaging system implementation. To achieve uniform multielement system sensitivity, substrates with low permittivity (ε r <5) and/or low thickness (h< 60 μm for the Si substrate) should be used. Finally, we investigate the operation of the detector array with optimally chosen substrate parameters together with the focusing lens, and show that the system is able to work as FPA without significant image corruption.

Sensitivity of Field-Effect Transistor-Based Terahertz Detectors

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Detection of IR and sub/THz radiation using MCT thin layer structures: design of the chip, optical elements and antenna pattern

“…Substrates were thick (from ≈400 up to 800 μm), which was the reason of antenna pattern degradation. In earlier studies [8,9], it was proposed to use electrically thin substrates (the substrate thickness h < 0.1λ d , where λ d is the wavelength inside the dielectric substrate). From the technological point of view, it is difficult to obtain thin substrates (d ≤ 60 µm) when excitation of substrate modes can be excluded.…”

Sub-THz nonresonant detection in AlGaN/GaN heterojunction FETs

“…To decrease the substrate influence of detector response on radiation frequency, the Al 2 O 3 substrates were back thinned to the thickness d = 175 µm. Besides the suppression of the resonance modes in the substrate, and improving the antenna gain, it makes the system less sensitive to changing the frequency of radiation [17].…”