STRUCTURE AND PHOTOCONDUCTION STUDIES OF DENSIFIED SILICON-NITRIDE

Photoconduction measurements have been made on commercially available hot-pressed polycrystalline silicon nitride. Characterization of the material was done using X-ray diffraction and scanning electron microscopy, which indicated poor processing and the presence of an unidentified impurity peak, probably due to the formation of an intermetallic compound. The photoconduction band gap obtained from the extrapolation of the photoresponse curves had a value between 4.9 and 5.1 eV for this material. The bandgap thus obtained shows a slow decrease with increasing applied voltage, which appears to be due to field-assisted photo-emission of charge carriers into the conduction band.