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

A theoretical model has been developed for recombination at dangling bonds which explains the γ variations between 0.5 and 1 depending on the Fermi level position. The occupation probabilities of the T3 + , T3° and T3 - states under illumination have been calculated using the statistics of correlated levels. The γ 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 5×10 15 cm -3 , a placing of the T3° level at 0.95 eV below E c , an effective correlation energy of 0.4 eV and a charged to neutral capture cross section ratio of 50.