Microstructure, electrical, and optical properties of evaporated PtSi/p-Si(100) Schottky barriers as high quantum efficient infrared detectors

The effects of the microstructure and the electrical and optical properties on the formation at highly efficient infrared PtSi Schottky barrier detectors (SBD) have been studied in detail. Two- to twelve-nanometer-thick PtSi films were grown by evaporation at temperature ranging from 350 to 550 °C. The electron diffraction patterns indicate the existence of both the (11̄0) and (12̄1) orientations when PtSi films formed at 350 °C. However, the diffraction patterns show only the (12̄1) orientation when the PtSi films are formed at 450 °C or above. The electrical barrier height of the Schottky barrier detector that formed at 350 °C was about 20 meV higher than that formed at 450 °C or above. The grain size and the film thickness had a negligible effect on the electrical barrier height. However, the optical performance was strongly dependent on the film thickness and the growth conditions. The 350 °C PtSi film showed increased quantum efficiency as the film thickness decreased. The optimal thickness that provided the highest responsivity was 2 nm. On the other hand, the optimal thickness shifted to 8 nm for PtSi film formed at 450 °C or above. These results indicate that the quantum efficiency of a detector can be improved if the PtSi film has an orientation at (12̄1), a larger grain size, and an optimal film thickness.