Density of states in Bi12TiO20 from time-of-flight measurements

Abstract

Two sillenite crystals of Bi12,TiO20, one intrinsic and one lead doped, have been studied by means of the time-of-flight (TOF) experiment. After a short presentation of the technique, we return to the different methods proposed to extract the transit time from the current transients recorded with the TOF experiment. Further, we illustrate the possibility of extracting the density of states from these transients by means of a Laplace transform applied to the variation with time of the transient currents. Then we present some experimental results. The room temperature drift mobilities we measured were equal to 2 and 0.2 cm2 V-1 s-1 for the lead doped and intrinsic sample, respectively. Finally we present the densities of states found for each crystal and compare them to the results obtained from modulated photocurrent experiments applied to the same samples.