Present status of TGS-based pyroelectric infrared detectors and computational simulation of their integration with silicon technology

Pyroelectric detectors of infrared radiation are fast-response thermal sensors operating at ambient temperature unlike semiconductor detectors, which require cooling. Their spectral response is uniform in a large range of wavelengths, including the main band of IR transmission within the earth's atmosphere. A further increase in pyroelectric response is possible by integrating pyroelectric sensors with silicon technology. Triglycine sulfate (TGS) based pyroelectric detectors are the most sensitive among available ferroelectric materials. Efforts made so far in improving their growth yield, mechanical properties and figures of merit for their use, as infrared detectors will be presented. Effective sensitivity and performance depend not only on the pyroelectric sensor element material characteristics, but also on the thermal performance of the complete structure of a detector, such as substrate material (Si), absorbing layer, and isolation layers including associated electronics. Thus, we have calculated the thermal transfer function by solving a one-dimensional thermal diffusion equation for a single element n-layer structure. From which the performance of any number of layers detector structure can be derived, predicted, and optimized. Using various single sensor configurations and pyroelectric parameters of modified TGS crystals grown in our laboratory; the calculated and predicted repsonsivity and other parameters of integrated detector system will be presented. The results obtained are encouraging for the development of TGS thin film based detectors.