Hydrogenated amorphous silicon germanium films doped with nitrogen (a-SiGe:H,N) to improve the long-wave infrared (LWIR) region absorption

Sensors in the long-wave IR region are used due to their enormous importance in technology for a variety of applications, as medical diagnostics, fire protection, automotive night vision, security and military, among others. This paper reports our study of hydrogenated amorphous silicon-germanium (a-SiGe:H) thin films deposited by low-frequency plasma-enhanced chemical vapor deposition (LF-PECVD), in order to be used as long-wave infrared (LWIR) sensing films in microbolometers. In order to improve the absorbance of the IR sensing films, they were doped with nitrogen (N 2 ) using different flow rates. FTIR measurements were performed to compare the absorption coefficient of the films doped with different N 2 flow rates, where was observed that effectively, the absorption in the 8 – 14 μm spectral range was improved for the films deposited with larger N 2 flow rates. Also, it was observed that the incorporation of N 2 in the a-SiGe:H films improves the room temperature conductivity (σ RT ) up to 3 orders of magnitude.