Uncooled Ni-Cr micro/nano-bolometers with NEP of 14 pW/Hz1/2

This paper presents air-suspended Ni-Cr micro/nano-bolometers with very low NEP. Analysis indicates that the thermal loss to the surrounding air cannot be ignored and therefore the reduction in the bolometer size leads to substantial improvement in the bolometer performance by minimizing the heat conduction in the air. Ni-Cr micro/nano-bolometers with a sheet resistance of 5.3-5.6 Ω/sq., widths of 0.6-2μm, and resistance up to 275 Ω are fabricated and tested at room temperature. The responsivity of the micro-bolometer (w_b=2 μm) saturates at 83 V/W due to the heat conduction from the surrounding air, while that of the nano-bolometer (w_b=0.6 μm) continuously increases up to 315 V/W. The nano-bolometer achieves a minimum NEP of 14 pW/√Hz for w_b=0.6 μm, l_b=20 μm, and R_b=184 Ω, which is ~2x better than published results and is in the state-of-the art level.