1.4 - Internal Thermal Amplification for Increasing the Responsivity of Pyroelectric Detectors

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings IRS² 2011
I1 - Photon and Thermal Detectors
Y. Querner, V. Norkus, G. Gerlach - Technische Universität Dresden (Germany)
30 - 35


This paper describes a new method for increasing the responsivity of pyroelectric detectors in voltage mode. A three-dimensional pattern is etched into the sensitive element. This leads to thicker electrical active areas and thinner electrical passive areas. In such a structure a lateral heat flux from thinner to thicker regions is generated due to faster heating of the thinner part based on minor thermal mass. This additional heat flow into the thicker electrically active areas increases the output signal of the sensors for equal radiation fluxes and hence increases the responsivity in contrast to an unstructured sensor.

The presentation gives an overview about the mathematical and physical analysis of the three-dimensional set-up. Both, an analytical and a numerical model were developed. The analytical model is based on the well-known thermal models of vertical and lateral heat conduction and is adapted to the new pattern. It allows the description of the thermal and electrical behavior of the sensitive element depending on the size of the structure and the modulation frequency. Furthermore, a finite element model was used to simulate the temperature distributions in the patterned area with much higher accuracy.

Furthermore, the technology of implementing this structure into the lithium tantalate is introduced and experimental proof has been obtained that the amount of responsivity increase and its frequency dependence strongly depend on the structure dimensions in the sensitive element.
Preliminary results for single-element detectors show an increase of responsivity by (10-25) % at a chopping frequency of 10 Hz. Simulation results show that improvements up to 150 % can be expected.