Realization of Single Layer Microbolometer Detector Pixel Using ZnO Material

Abstract

This paper presents the realization of a single layer microbolometer pixel fabricated using only ZnO material coated with atomic layer deposition. Due to the stress-free nature and high temperature coefficient of resistance of the ALD coated ZnO material, it can be used both as structural and active layers in microbolometer detectors. The design, simulations, and the fabrication optimization of two types of single layer ZnO microbolometer having pixel pitch of $35~\mu \text{m}$ are shown in this study. The designed pixels have thermal conductances of 58 nW/K and 476 nW/K while their thermal time constant values are 1.62 ms and 0.24 ms. The temperature coefficient of resistance and 1/f corner frequency of fabricated resistors are measured to be −10 %/K and 302.5 Hz respectively. The absorption coefficients of both pixels are measured to be around 40 % in 8- $12~\mu \text{m}$ wavelength range. The fabricated pixels are the first examples of successfully obtained single layer ZnO microbolometer pixels in literature and the proposed structures can be used to decrease the design complexities and fabrication costs and increase the yield of the detectors making them possible to be used in low-cost applications.