Study of the properties of electro-physical parameters in spatially incoherent crystal semiconductors on the example of layered AIIIBVI semiconductor compound crystals

The results of experimental measurements of the dependence of electrophysical parameters (specific electrical conductivity, Hall coefficient and mobility of free main charge carriers) on temperature, electric field intensity, chemical nature and amount of the added dopant in layered indium monoselenide (n-InSe) single crystals without dopant (pure) and doped with dysprosium (Dy), erbium (Er) rare earth elements (REE) in various amounts (NREE=10-4-10-1 at.%) were interpreted and analyzed, and the reasons for the deviation of these results from the existing theoretical provisions for the electrophysical parameters of quasi-ordered crystalline semiconductors at low (Т<230÷250K) temperatures were explained. It has been shown that the main reason for these deviations is the formation of random macroscopic defects (RMD) in the volume of samples of these crystals due to the dominance of weak molecular (Van-der-Waals) bonds in the direction perpendicular to the layers, in contrast to the layered structure of n-InSe crystals and the strong covalent bonding in the direction of their natural layers. The crystals of this semiconductor can be generally described as a "semiconductor-semiconductor composite material" consisting of a low-ohm main matrix and a chaotically distributed higher-ohm "dispersant" with the same chemical composition and crystal structure in that matrix. The values of the electrophysical parameters in this type of composite material, as well as the nature of their dependence on various external factors, can be purposefully controlled by changing the amount of the included REE additive. It is possible to use pure and doped crystals of n-InSe as a convenient model for studying the properties of electrophysical parameters in generally spatially non-uniform crystalline semiconductors and semiconductor-semiconductor composite materials.