New Scheme for the Detection of Optical Radiation in the External Photoemissive Mode: Device Implementation.

摘要

The work undertaken this year included setting up equipment for and making absorption measurements of Ag/n-Si composite films containing 3x10e+19 per cubic centimeter of antimony and various Ag at. %. The absorption was greater than 50 % from 1-14 microns wavelength. A complete inhouse responsivity facility was setup for measuring responsivity, signal-to-noise ratios and detectivity for composite films from room down to liquid nitrogen temperatures. Those films containing 13 at. % Ag were found to have the highest responsivity. Room temperature responsivities in the 1-2 micron wavelength were routinely fabricated and found to be due to composite behavior and not due to the silicon matrix alone. Transport measurements indicated that in films with greater than 20 at. % Ag, the Ag acted as a dopant producing room temperature carrier concentrations larger than three orders of magnitude than that due to the antimony alone, producing films with extremely low resiistivities and very narrow depletion regions between the Ag and Si. This will help to make tunneling of photoexcited electrons from the Ag nanoparticles into the silicon conduction band much easier.