ELECTRONIC AND IR-OPTICAL PROPERTIES OF SILICIDE SILICON INTERFACES

Responsivity measurements of silicide/silicon IR detectors, i.e. PtSi/Si and IrSi/Si are interpreted in the light of physical models for photoemission. The quantum yield for photoemission is composed of the optical absorption and the electrical emission yield which impose partially conflicting requirements for the optimization of the silicide thickness. For thin (2-6 nm) silicide films, the IR responsivity is enhanced by diffuse wall scattering of charge carriers at the interfaces. The enhancement is high near the long wavelength cut-off of the detector and decreases to shorter wavelengths due to inelastic scattering of mobile carriers for increasing photoexcitation energy. The electronic properties of the interface are also characterized by tunneling spectroscopy. The results indicate a disordered interface which is created by interdiffusion of the components at elevated temperatures for silicide formation. Interdiffusion increases the emission barrier and reduces the responsivity.