Amorphous semiconductor mobility limits

•A physics-based model for mobility in an amorphous semiconductor is developed.•The maximum mobility of a thin-film transistor is estimated.•The nature of disorder in an amorphous semiconductor is discussed.•Decreasing the band tail state density and the effective mass are key.

A physics-based model for electron and hole mobility in an amorphous semiconductor is developed to estimate the mobility limits of an amorphous semiconductor. The model involves band tail state trapping of a diffusive (Brownian motion) mobility and accounts for both drift- and diffusion-induced transport, as normally encountered in the operation of a thin-film transistor. Employing this model leads to a predicted maximum mobility of ~70 cm2V-1s-1 (~10 cm2V-1s-1) for electrons (holes).