Electrical Properties of Ge/Ge(x)Si(1-x) thin films on the boundary of semiconductor-dielectric transition

Calculations of the dependencies of carrier concentration and specific electrical conductivity at room temperature for the undoped and doped germanium nanofilms, grown on the Ge(x)Si(1-x) substrate with crystallographic orientation (001), on a film thickness and substrate composition, have been provided based on the theory of electrical conductivity for the two-dimensional semiconductor nanostructures. It was established that the dielectric-semiconductor transition for thin germanium films with a thickness of can be achieved either by increasing the film thickness, which reduces the effectiveness of quantum size effects or by increasing the silicon content in the Ge(x)Si(1-x) substrate. The latter increases the internal mechanical stress in the film and, consequently, the concentration of intrinsic current carriers. Doping such germanium film by the donor impurities with the ionization energy also leads to the implementation of the dielectric-semiconductor transition. The presented calculations of the electrical properties of germanium thin films can be utilized in developing the scientific foundations for their synthesis and in designing channels of the n-MOSFET and n-MODFET transistors, lasers based on heterojunctions, and electro-optical modulators based on such films.