Micromachined, silicon filament light source for spectrophotometric microsystems

A miniature broadband light source is a critical element in a spectrophotometric microsystem. The design, fabrication, and characterization of a highly stable, miniature broadband light source that comprises filaments of single-crystal silicon are presented. Electrical current versus voltage and radiant emittance spectra under constant voltage bias are measured and related to filament dimensions. A maximum stable operating temperature for these filaments is estimated to be 1200 K. Resistance drift is demonstrated to be less than 0.5% over a 10-h period of continuous operation with visible incandescence. Emittance spectra of a multifilament array, measured at three different electrical biases, are presented and shown to compare well with theoretical blackbody radiation spectra. A continuous, total radiated power of 10.7 mW was achieved with a 1 mm x 1 mm filament array with peak emittance at lambda=2.7 micrometers.