Fabrication and performance comparison of planar and sandwich structures of micro-bolometers with Ge thermo-sensing layer

Two types of micro-bolometer structures were fabricated with the same materials and fabrication process. The structures are labeled planar and sandwich types. Their performance was measured and a comparison was performed among these structures. Our results show that the sandwich type structure behaves better in terms of the voltage and current responsivity, but shows 2 to 3 orders of magnitude higher 1/f noise levels. In spite that the sandwich configuration shows a lower response time constant than that of the planar device, the noise level makes the detectivity of both devices practically the same.