Improved Thermopile on Pyramidally-Textured Dielectric Film

In this letter, we pattern thermocouples on the surface of pyramidally-textured dielectric film by careful control of etching and lithography process successfully. Taking advantage of the low thermal conductance and high infrared absorption of the textured dielectric film, the temperature difference between the hot and cold junctions can be increased when this dielectric-film absorber is heated by IR radiation. The fabricated thermopile with 184 pairs of P+poly-Si/Au thermocouples has responsivity, detectivity, and response time constant of 147.21±4.39 V·W
^-1
, 1.71±0.04 × 10
⁸
cm·Hz
^1/2
·W
^-1
, and 9.44±0.25 ms in air, respectively.Compared to the controlled thermopile based on flat dielectric film, the responsivity and detectivity are significantly improved by more than 58%, while the time constant is still kept less than 10 ms. These results indicate the feasibility of patterning thermocouples on the surface of pyramidally-textured dielectric film for achieving high-performance thermopiles.