Band tails, entropy, and equilibrium defects in hydrogenated amorphous silicon

Abstract

A method of calculation of the equilibrium defect concentration for a disordered semiconductor with exponential band tails is presented. For hydrogenated amorphous silicon, the entropy-of-mixing term in the expression for the free energy is found by consideration of the dangling bonds as an impurity in a system of bonding orbitals. These calculations are compared with experimental results.