Temperature dependence of the 2.2-eV pair-recombination band in GaP(S,C) crystals

The dependence on temperature of the GaP(S,C) pair-recombination emission at 2.2 eV has been investigated. The peak energy $E_m$ was almost constant up to about 35°K, and shifted to lower energies at higher temperatures tending towards a minimum above 60°K. An analytical expression for the shift of $E_m$ with temperature was derived and compared with the experimental values. Half-widths of the 2.2-eV band varied at liquid-helium temperature between 16 and 32 meV depending on excitation intensity. On warming, the high-excitation half-widths dropped towards those obtained at low excitation. The emission at a fixed wavelength decreased on warming, and above 40°K gave activation energies which could be described by the sum of the binding energies minus the Coulomb energy of the pair ($E_d+E_a-E$). The 2.2-eV band was accompanied by a satellite band near 2.19 eV. Half-widths and peak energies of the 2.2-eV band were corrected in the present work for the contribution of the satellite.