The measurement of electrical properties of uncontaminated PbTe films prepared by molecular beam deposition

Abstract

Describes the methods used to prepare uncontaminated PbTe films on mica substrates by molecular beam deposition from a single source boat and the techniques used to make in situ electrical measurements on the films down to 100K. The as-grown carrier concentration was found to be determined by source conditions and controllable n-type carrier concentrations between 1022 and 5*1024 m-3 could be obtained. Measurements on films having the lowest carrier concentration indicated that they contained a low residual doping level (<1021 m-3). Room-temperature Hall mobilities improved as the runs progressed and a maximum value of 0.195 m2 V-1 s-1 was obtained. Films with carrier concentrations greater than 5*1023 m-3 had field effect mobilities of approximately 0.08 m2 V-1 s-1. Exposure of the films to low pressures of oxygen after growth enabled the n-type doping to be reduced to any level down to intrinsic carrier concentrations.