State of the Art in GaP Electroluminescent Junctions

Although the recombination radiation from forward-biased GaP p-n junctions could be used for the same applications as the emission from lower band-gap materials (e.g., in photon-coupled circuitry), the GaP emission occurs mainly in the visible portion of the spectrum and is thus more appropriate for applications where the human eye is the detector. To obtain emission in the visible from a forward-biased p-n junction, one needs a semiconductor with a band gap greater than I.8 eV. The I I - V I compounds that meet this requirement cannot be made into simple p-n junctions (although some of their alloys can). Hence, only GaP, BP and the various polytypes of SiC are considered. (These are all indirect gap semiconductors so that stimulated emission is not normally expected.) Of these three, GaP (banc! gap 2.26 eV) is characterized by the simplest materials technology.