Hot Electron Spectroscopy in Molecular Crystals

Abstract

The well-known phenomena of electrons passing through a large potential gradient and tunnelling through a thin insulating layer across which a voltage is applied have been employed t o obtain sufficiently energetic electrons for thermionic emission to be observed at room temperature.^1,2,3 The tunnelling effect has also been used to inject carriers into silicon⁴ and n type CdS.⁵ In this note we report some preliminary results of experiments utilizing these effects to inject electrons into molecular crystals. While at present these results are not yet precise, they indicate that this technique may be very useful for the investigation of the nature of the conducting states in insulating materials. We have used both a, reversed biased silicon p-n junction and a metal-metal oxide-metal arrangement to obtain hot electrons (most of our results were obtained by the former). In this way we have obtained information on the position of what is presumably the lowest conductivity band. At present we have results only on anthracene, although other crystals are also heing investigated.