Temperature-dependent effects in field-effect measurements on hydrogenated amorphous silicon thin-film transistors

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Abstract
The activation energy of the source-drain current I SD in hydrogenated amorphous silicon thin-film transistors shows a correlation with the extrapolated intercept of I SD for 1/T →0 which resembles the Meyer-Neldel rule found in transport measurements on bulk samples. Previous interpretations of the Meyer-Neldel rule in field-effect experiments are discussed in detail. A unified analysis of this effect is given. The field-effect technique provides an alternative experimental method for determining the microscopic prefactor σ0 of the bulk conductivity. The accuracy of this approach is examined. It is found that 20 Ohm;−1 cm−1 < σ0 < 2000Ω−1 cm−1, the most probable value of σ0 being about 100Ω−1.cm−1. It is pointed out that knowledge of σ0 is required in order to determine the field-effect density-of-states distribution in the tail region from field-effect measurements.