Hall mobility for electrons in undoped a-Si:H

The Hall mobility μH of electrons in undoped a-Si:H has been measured between 200 and 550 K under illumination and in the dark. There are two distinct regimes: below Tt =360 K is independent of temperature, with a value μH ∼0.1 cm2 V−1 sec−1; above Tt, μH = 7.9 exp (−0.13 eV/kT) cm2 V−1 sec−1. The data can be fitted by a model where there is one set of conducting states for electrons and two possible modes of transport. Above Tt conduction is by thermally activated hopping; below Tt it takes place either by tunneling or by a temperature-independent jumping process. Conduction does not take place through extended states in the temperature range 200 – 550 K.