Radiation Resulting from Recombination of Holes and Electrons in Silicon

Abstract

Radiation produced in silicon by the recombination of excess electrons and holes in thermal equilibrium with the crystal lattice has been examined both at room temperature and at 77 °K. The radiation obtained at room temperature is shown to be an intrinsic property of silicon. It is probably due to indirect transitions of electrons from the conduction band minima to the valence band with phonon cooperation. Additional radiation is found at 77 °K which is structure sensitive, or extrinsic. This radiation is shown to be produced by the recombination of excess carriers with unionized donor and acceptor impurities. The energy distribution of the photons of intrinsic radiation gives values of the energy gap which are in good agreement with those determined in other ways. Differences between the photon energies associated with the maximum photon emission of intrinsic and extrinsic radiation are in semi-quantitative accord with accepted values of ionization energies of the donor and acceptor impurities introduced in the crystal growing process.