Critical process issues in selenization

Both H₂Se and elemental selenium are used to form copper-indium diselenide. Equilibrium thermodynamic calculations for H ₂Se dissociation show that the higher-order Se_x species (Se₅, Se₆, Se₇) are important at temperatures below 800 K, whereas Se₂ becomes the predominant species at temperatures above 900 K. A kinetic model is presented for the decomposition of H₂Se. The reaction is found to be first order at short times, but the reverse reaction of Se _x with H₂ assumes importance at higher conversions and longer times. The constants in the kinetic model are calculated