Detection of infrared photons using the electronic stress in metal-semiconductor interfaces

It is well known that the work function of metals decrease when they are placed in a nonpolar liquid. A similar decrease occurs when the metal is placed into contact with a semiconductor forming a Schottky barrier. We report on a new method for detecting photon is using the stress caused by photon-electronics emitted forma metal film surface in contact with a semiconductor microstructure. The photoelectrons diffuse into the microstructure and produced an electronic stress. The photon detection results from the measurement of the photo-induced bending of the microstructure. Internal photo-emission has been sued in the past to detect photons, however, in those cases the detection was accomplished by measuring the current due to photoelectrons and not due to electronic stress. Small changes in position of microstructures are routinely measured in atomic force microscopy where atomic imaging of surface relies on the measurement of small changes in the bending of microcantilevers. In the present work we studied the photon response of Si microcantilevers with a thin film of Pt. The Si microcantilevers. In the present work we studied the photon response of Si microcantilevers with a thin film of Pt. The Si microcantilevers were 500 nm thick and had a 30 nm layer of Pt. Photons with high enough energies produce electrons from the platinum-silicon interface which diffuse into the Si and produce an electronic stress. Since the excess charge carriers cause the Si microcantilever to contact in length but not the Pt layer, the bimaterial microcantilever bends. In our present studies we used the optical detection technique to measure the photometric response of Pt-Si microcantilevers as a function of photon energy. The charge carriers responsible for the photo-induced stress in Si, were produced via internal photo-emission using a diode laser with wavelength (lambda) equals 1550 nm.