Deconvolution of temperature dependence of conductivity, its reduced activation energy, and Hall-effect data for analysing impurity conduction in n-ZnSe

摘要

The temperature dependence of the reduced activation energy w = ε/kBT of the conductivity σ has been utilised for determining the impurity conduction mechanism in doped semiconductors in many studies. Herein, the formula for deconvoluting w when plural conduction mechanisms appear is used to confirm the analysis of the data of the Hall-effect measurements on Al-doped n-ZnSe samples. The analysis is performed on the basis of an impurity-Hubbardband model which includes ε_2 conduction in the top Hubbard band as well as ε3 and Efros-Shklovskii (ES) variablerange hopping (VRH) conduction processes in the bottom Hubbard band. As the result of the analysis, transitions among the three hopping conduction mechanisms of ε_2, ε3, and ES VRH are clearly shown in the temperature dependence of w as well as in that of the Hall mobility, which are hardly noticed in the temperature dependence of σ. In addition, the power-law exponent of the prefactor of ES VRH conductivity is determined through the fit to the temperature dependence of w to show that it decreases from ~ 1.5 to ~ 0 with increasing net donor concentration.