Un-cooled Micro-bolometer with Sandwiched Thermo-sensing Layer Based on Ge Films Deposited by Plasma


An un-cooled micro-bolometer with thermo-sensing layer sandwiched between two electrodes has been fabricated and characterized. The micro-bolometer has a “bridge” configuration for providing sufficient thermo-isolation of the thermo-sensing layer. Surface micro-machining techniques were used for its fabrication onto a silicon wafer. The support layer is of SiN and the thermo-sensing layer is a-Ge:H,F film, both have been deposited by low frequency PE CVD technique. The active area of the thermo-sensing layer is AB = 70×66 µm2. The temperature dependence of conductivity σ(T), current-voltage characteristics I(U), spectral noise density and thermal response time have been measured in order to characterize its performance characteristics. The measured activation energy of the thermo-sensing layer is Ea = 0.34 eV providing a thermal coefficient of resistance α = 0.043 K-1. The pixel resistance is in the range of RB = (130)x105 Ohm. Measured current and voltage responsivities are in the range of ℜI = 0.314 AW-1 and ℜU = (12)105 VW-1, respectively. The estimated value of the detectivity is in the range of D* = (140)x108 cmHz1/2W-1 and the obtained response time is τ = 1x10-4 sec. The performance characteristics obtained in this micro-bolometer with sandwiched thermo-sensing layer make it promising for further development of IR imaging systems.

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Kosarev, A., Moreno, M., Torres, A. et al. Un-cooled Micro-bolometer with Sandwiched Thermo-sensing Layer Based on Ge Films Deposited by Plasma. MRS Online Proceedings Library 910, 1705 (2005). https://doi.org/10.1557/PROC-0910-A17-05

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