Investigation of boron-doped hydrogenated silicon films as a thermo-sensing layer for uncooled microbolometer

Abstract

Boron-doped hydrogenated silicon films are used in thermo-sensing layer in infrared detectors or uncooled microbolometers. Among thermo-sensing materials such as vanadium oxide and amorphous silicon and silicon diodes, amorphous silicon is the most common. Parameters such as the temperature coefficient of resistance (TCR), sheet resistance and 1/f noise are very important for the performance of these devices. One thermo-sensing material in particular, boron-doped hydrogenated silicon (BSi:H), has satisfactory TCR, sheet resistance (Rsheet), and 1/f noise values. The BSi:H films are deposited using radio frequency plasma-enhanced chemical vapor deposition. The dependence of electrical, structural, and chemical properties of the BSi:H films on the plasma parameters is reported. The TCR of the films is 1.0–2.9%/K, Rsheet is 1.2–37.8 MΩ/Υ and crystalline volume fraction is 10.2–68.5%. The properties of the amorphous and mixed-phase are compared. It is found that the 1/f noise of the mixed-phase film is lower than that of the amorphous phase film. These results show that the boron doped mixed-phase silicon films are suitable for use as thermo-sensing layers.