Applicability of Electrical Conductivity Ratio Method to Complicated Band Structure and the Carrier Scattering Mechanisms of SnSe

The electrical conductivity ratio (ECR) method can be used to analyze carrier scattering mechanism (CSM) without the need of magenetic transport measurements. In this work, the applicability of the ECR method in the analysis of complex energy band structures is discussed. Combined with the thermoelectric properties of SnSe, the feasibility using ECR method of ideal single band transport model to study the CSM of semiconductor materials with complicated band structure is studied. The results indicate that ECR method is not only applicable to idea band structure as reported before but also to the complicated band structure. The analysis results of the CSM of single crystal SnSe by ECR method using ideal single-band model agree with the carrier mobility temperature dependence in the nonphase transition temperature range. The CSM along three direction of single crystal SnSe are different because of its anisotropic crystal structure. The difference between dislocation scattering (DS) and charged impurity scattering (CIS) is that DS is always accompanied by polar optical phonon scattering (POP), such as the CSM of SnSe along b axis direction. The difference between CIS and DS can be more easily distinguished by the ECR method than the carrier mobility temperature dependent method. DS and POP might be one of the approaches to improve thermoelectric property because the scattering factor for DS or POP is larger than that of acoustic phonon scattering (APS) and alloy scattering (AS). For polycrystalline SnSe, the carrier scattering mechanisms varies with the crystal structure and the temperature. This indicates that the ECR method can better reflect the variation of carrier scattering mechanisms with temperature compared to the carrier mobility temperature dependence method.