Fabrication and performance of a double layered Mn-Co-Ni-O/Mn-Co-Ni-Cu-O thin film detector

A thermal sensitive infrared and THz detector was fabricated by a double layered Mn-Co-Ni-O/Mn-Co-Ni-Cu-O films. The Mn-Co-Ni-O material, as one type of transition metal oxides, has long been used as a candidate for thermal sensors or infrared detectors. The resistivity of a most important Mn-Co-Ni-O thin film, Mn₁. ₉₆Co_0.96Ni_0.48O₄(MCN) , is about 200 Ω·cm at room temperature, which ranges about 2 orders larger than that of VOx detectors. Therefore, the thickness of a typical squared Mn-Co-Ni-O IR detector should be about 10 μm, which is too large for focal plane arrays applications. To reduce the resistivity of Mn-Co-Ni-O thin film, 1/6 of Co element was replaced by Cu. Meanwhile, a cover layer of MCN film was deposited onto the Mn-Co-Ni-Cu-O film to improve the long term stability. The detector fabricated by the double layered Mn-Co-Ni-O/Mn-Co-Ni-Cu-O films showed large response to blackbody and 170 GHz radiation. The NEP of the detector was estimated to be the order of 10^-8 W/Hz^{0. 5}. By applying thermal isolation structure and additional absorption materials, the detection performance can be largely improved by 1-2 orders according to numerical estimation. The double layered Mn-Co-Ni-O film detector shows great potentials in applications in large scale IR detection arrays, and broad-band imaging.