Material response of metasurface integrated uncooled silicon germanium oxide SixGeyO1-x-y infrared microbolometers

This paper presents a study of metasurface integrated microbolometers. The semiconductor absorber is sandwiched between a metal Frequency-Selective Surface (FSS) and ground plane. When the semiconductor absorber is electrically isolated from the ground plane by a thin dielectric it can be used to measure the temperature of the pixel. The integration with the FSS removes the need for a Fabry-Perot cavity. The FSS allows control the attributes of radiation absorbed by the microbolometer on a pixel-by-pixel basis which provides the potential for spectral or polarimetric imaging. The FSS also affects he electrical performance of the semiconductor absorber and the thermal performance of the microbolometer. In addition, the complex permittivity of the semiconductor affects the optimal design of the FSS. The Si/Ge/O system is selected because it allows the properties of the absorber to be engineered (e.g., less oxygen gives lower absorptance and higher resistivity). This paper explores the absorber/FSS parameter space with an emphasis on the electrical and noise properties of the integrated system. Models are developed to explain results. Preliminary results show that the addition of the FSS improves TCR of the microbolometer by 10% while dramatically lowering its resistivity (factor of 5×). The resistivity reduction leads to a dramatic reduction of the noise power spectral density with the addition of FSS improving the measured 1/f noise by two orders of magnitude over an identical sample without the FSS. In addition, this paper will present the microbolometer figures of merits including voltage responsivity, detectivity, and thermal response time.