AVS 46th International Symposium
    Thin Films Division Wednesday Sessions
       Session TF+MM-WeM

Paper TF+MM-WeM1
Detection of Photons Using Thin Films in Semiconductor MEMS

Wednesday, October 27, 1999, 8:20 am, Room 615

Session: Thin Films in MEMS and MOEMS
Presenter: P.G. Datskos, Oak Ridge National Laboratory
Authors: P.G. Datskos, Oak Ridge National Laboratory
S. Rajic, Oak Ridge National Laboratory
I. Datskou, Environmental Engineering Group, Inc.
Correspondent: Click to Email
We report on a new method for detecting photons using the stress caused by photoelectrons emitted from a thin metal film surface in contact with a semiconductor microstructure which forms a Schottky barrier. As photoelectrons diffuse from the metal film into the microstructure they produce an electronic stress. The photon detection results from the measurement of the photo-induced bending of the microstructure. Internal photoemission has been used 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 (displacement) of microstructures are routinely measured in atomic force microscopy (AFM) where atomic imaging of surfaces relies on the measurement of small changes (< 10@sup -9@ m) in the bending of microcantilevers. In this work we studied the photon response of Si microcantilevers coated with a thin film of Pt. The Si microcantilevers were 500 nm thick and had a 30 nm layer of Pt. Photons with sufficient 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 contract 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 photoemission using a 1550 nm wavelength diode laser.