PtSi

PtSi, or platinum silicide, is a binary intermetallic compound with the chemical formula PtSi. It forms in a 1:1 platinum-to-silicon stoichiometry and behaves as a narrow-bandgap semiconductor. The material has a band gap of about 0.3 eV, which corresponds to sensitivity in the mid-infrared, roughly up to 4 micrometers in wavelength, depending on temperature and device structure. PtSi is compatible with silicon processing and can be produced as a thin PtSi layer on silicon by annealing a deposited Pt film or by diffusion of Pt into Si at elevated temperatures, forming the PtSi intermetallic at the interface.

In infrared detector technology, PtSi has been used to fabricate photodiodes and infrared imaging devices for mid-infrared applications such as imaging and spectroscopy. Devices typically operate at cryogenic temperatures to suppress dark current, with many historical detectors designed for operation around 77 K. PtSi offered the advantage of silicon compatibility and relatively straightforward fabrication compared with some other mid-infrared materials, but it has a limited long-wavelength response and lower performance at higher operating temperatures compared with modern detector materials such as HgCdTe or InSb.

The use of PtSi has declined in favor of more sensitive and temperature-tolerant materials, but PtSi detectors remain of historical importance and are still studied in research contexts for understanding narrow-gap silicides and silicon-based IR photodetection.