Thermally Isolated Ruthenium Nanobolometer for Room-Temperature Operation

We propose a bolometer intended for room-temperature operation and based on a 100-nm-wide ruthenium (Ru) strip fabricated on a thin layer of cross-linked polymethyl methacrylate (XPMMA). This layer provides thermal isolation between the silicon substrate and the Ru nanostrip for increasing the nonlinearity of the bolometer {I}-{V} curve due to more intensive self-heating by the biasing and an ac current. A number of bolometers with Ru strips of different dimensions and different thicknesses of XPMMA layer were fabricated and tested at dc. An estimate based on the dc tests gives the electrical voltage responsivity to radio frequency (RF) signal as much as 250 V/W, which makes the proposed bolometer attractive as a sensing element for a simple and low-cost microwave and terahertz detector. Numerical simulations of temperature distribution along the Ru strip and analysis of the bolometer noise performance are also presented.