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

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.