IR sensors based on silicon–germanium–boron alloys deposited by plasma: Fabrication and characterization

Abstract We report the study of a fabrication process and characterization of a thermal IR sensor based on silicon–germanium–boron alloys (a-Si x Ge y B z :H) deposited by plasma at low temperature. The sensor is an un-cooled micro-bolometer fabricated with surface micro-machining techniques and is fully compatible with the CMOS technology. The temperature dependence of conductivity σ ( T ) was measured in the sensor in order to calculate the activation energy, E a , the temperature coefficient of resistance, TCR and the room temperature conductivity, σ RT . Current–voltage characteristics, I ( U ), in darkness and under IR radiation were measured in the device in order to calculate its current responsivity, R I . Spectral noise density was measured and the micro-bolometer detectivity, D ∗ was calculated. The thermal time constant of the micro-bolometer was also measured.