FAR-INFRARED FREE-HOLE ABSORPTION IN EPITAXIAL SILICON FILMS FOR HOMOJUNCTION DETECTORS

We report on the investigation of free-carrier absorption characterist ics for epitaxially grown p-type silicon thin films in the far-infrare d region (50-200 mu m), where Si homojunction interfacial workfunction internal photoemission (HIWIP) detectors are employed. Five Si thin f ilms were grown by molecular beam epitaxy on different silicon substra tes over a range of carrier concentrations, and the experimental absor ption data were compared with calculated results. The free-hole absorp tion is found to be almost independent of the measured wavelength. A l inear regression relationship between the absorption coefficient and t he carrier concentration, in agreement with theory, has been obtained and employed to calculate the photon absorption probability in HIWIP d etectors. (C) 1997 American Institute of Physics.