LOW-TEMPERATURE EFFECTS ON THE GALVANOMAGNETIC PROPERTIES OF THIN PBTE FILMS

The microstructure of PbTe films, deposited on crystalline (mica) and amorphous (carbon) substrates was studied by transmission electron mic roscopy and electron diffraction. The activation energy of films of th ickness 0.5 mu m was 0.317 eV, calculated from resistivity-temperature measurements. The Hall constant decreases with magnetic field increas e at 80 K and 140 K, giving a Hall factor of less than unity. The vari ation of magnetoresistance with magnetic field was studied for magneti c fields up to 10 kG (1T), and at a temperature of 80 K. Due to the lo w mobility of carriers in the studied films, the quadratic relation be tween the magnetoresistance and the product of mobility and the magnet ic field was not verified, even at low temperature. The inhomogeneity of the fi Im was studied using the relationship between the magnetores istance and the angle between the electric current and the magnetic fi eld at 90 K and 200 K. It is proposed that magnetoresistance minima al ong the [200], [220] and [222] directions are caused by excess Pb alon g these directions due to non-stoichiometric composition of PbTe films .