The Photoconductivity Exponent For Recombination At Dangling Bonds In a-Si:H

Abstract

A theoretical model has been developed for recombination at dangling bonds which explains the y variations between 0.5 and 1 depending on the Fermi level position. The occupation probabilities of the T3+, T3 0 and T3states under illumination have been calculated using the statistics of correlated levels. The y exponent is derived through a parametric representation of the equations of detailed balance and charge conservation. A good agreement with experiment is obtained with a dangling bond density of 5x1015 cm-3 , a placing of the T3 0 level at 0.95 eV below Ec,an effective correlation energy of 0.4 eV and a charged to neutral capture cross section ratio of 50.

On the relationship between photoconductivity and light intensity in solids

“…In their analysis average values o f the gap-state densities between the electron quasi-Fermi level and the equilibrium Fermi level were used and no recombination was permitted via the states below the midgap. Halpern (1986) and Vaillant and Jousse (1986) have also analysed this exponent localised gap state has three possible charge values, namely. neutral, negatively or positively charged.…”