Pyroelectric detectors are used for gas analysis and flame detection because of their fast response and excellent performance. Most pyroelectric devices are based on monocrystalline lithium tantalate or pyroelectric lead zirconate titanate thin films deposited on a silicon (Si) substrate. In comparison, recently discovered pyroelectric-doped hafnium oxide (HfO 2 ) offers the possibility of manufacturing completely complementary metal-oxide-semiconductor (CMOS)compatible devices on large Si wafers. This is a promising approach to simplifying mass production of the sensor element and realizing new sensor structures with a high performance. Si substrates were structured with trenches and filled with thin-doped HfO 2 layers by atomic layer deposition to multiply the pyroelectric current responsivity. An effective pyroelectric coefficient of up to 1300 μC∕m 2 ∕K was measured. Micromechanical structuring of the 6-in Si wafers was used to improve the thermal conversion of the sensor element. The applied plasmonic absorbers increase the infrared light absorption to >80% for the spectral range of 3 to 5 μm, which was determined using Fourier transform infrared reflection measurements. In the first step, the performance of the sensor element was evaluated with an analog transimpedance amplifier with a feedback resistance of 5 GΩ. A specific detectivity D Ã > 1 • 10 7 cm p Hz∕W was measured for the frequency range of 1 to 10 Hz. In addition, an application-specific integrated circuit was designed for the electrical signal conditioning to build a fully CMOScompatible pyroelectric detector. It offers a simple to manufacture, flexible configuration, and digital communication interface with a signal-to-noise performance close to analog detectors. We present the measurement results of different sensor elements and detector types.
The combined evaluation of the thermal and electrical domain of a pyroelectric system is a challenging task. The proposed approach precisely models the thermal system with FEM. The output data is approximated with a fit function and transferred to SPICE creating a universal and adaptable model for the whole pyroelectrical signal chain. For validation, the InfraTec detector LRM-244 is used.
The signal conditioning of sub-pA pyroelectric currents with a monolithic circuit is a challenging task. A switched capacitor enables the emulation of high-ohmic resistance values in the GΩ-range for a high amplification on a small chip area. Different circuit topologies are simulated and measured whereby the realized digital detector achieves a specific detectivity of 2.5 • 10 8 cm√Hz/W at 10 Hz.
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