Boron doping compensation of hydrogenated amorphous and polymorphous germanium thin films for infrared detection applications

• We reported boron doping compensation of amorphous and polymorphous germanium.
• The films were deposited by plasma enhanced chemical vapor deposition.
• The aim is to use the films as thermo-sensing elements in un-cooled microbolometers.
• Those films have advantages over boron doped a-Si:H used in commercial detectors.

In this work we have studied boron doping of hydrogenated amorphous germanium a-Ge:H and polymorphous germanium (pm-Ge:H) in low regimes, in order to compensate the material from n-type (due to oxygen contamination that commonly occurs during plasma deposition) to intrinsic, and in this manner improve the properties that are important for infrared (IR) detection, as activation energy (Ea) and temperature coefficient of resistance (TCR).Electrical, structural and optical characterization was performed on the films produced. Measurements of the temperature dependence of conductivity, room temperature conductivity (σRT), Ea and current–voltage characteristics under IR radiation were performed in the compensated a-Ge:H and pm-Ge:H films. Our results demonstrate that, effectively, the values of Ea, TCR and IR detection are improved on the a-Ge:H/pm-Ge:H films, using boron doping in low regimes, which results of interest for infrared detectors.