A MEMS infrared thermopile with phononic crystal structures and carbon nanotube absorption layer

We have fabricated MEMS infrared thermopiles from a silicon-on-insulator substrate where the buried oxide layer was used to form a membrane for thermal isolation of the detection area. The silicon wires of the thermocouples were patterned with a phononic crystal structure that consisted of 200nm holes on a 400nm pitch. The silicon was degenerately doped using a spin on dopant process to create the p, n-type regions. The absorption layer used was a 20um tall vertically-aligned, multi-walled, carbon nanotube layer. We measured the performance of our devices to have a D* of 3 * 10
⁷
cmHz
^0.5
W
^-1
and a time response of 5-8 msec. We believe the performance of our design can be improved to exceed a D* of 10
⁸
cmHz
^0.5
W
^-1
by patterning the absorption layer.