Photon degradation effects in terrestrial solar cellsA certain type of photon degradation effect has been observed experimentally in n(+)/p solar cells. It is found that this effect is caused by a recombination center, the formation of which requires the simultaneous presence of a lattice defect and a silver atom or complex of atoms. The center is electrically active in its equilibrium state; the energy level of the inactive center is located in the band gap, 0.37 eV below the conduction band. Conversion to an active recombination center can be brought about either by raising the minority carrier quasi-Fermi level to coincide with the position of the latent center level in the band gap or by the direct excitation of electrons from the valence band to the latent center level. Photon degradation can be prevented either by preventing the introduction of silver through the use of a clean diffusion system and clean initial material or by eliminating lattice damage through sufficient surface material removal prior to diffusion while at the same time restricting diffusion temperatures to 875 C or below.
Document ID
19790057085
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Weizer, V. G. (NASA Lewis Research Center Cleveland, OH, United States)
Brandhorst, H. W. (NASA Lewis Research Center Cleveland, OH, United States)
Broder, J. D. (NASA Lewis Research Center Cleveland, OH, United States)
Hart, R. E. (NASA Lewis Research Center Cleveland, OH, United States)
Lamneck, J. H. (NASA Lewis Research Center Cleveland, Ohio, United States)