Investigação das propriedades elétricas em poços quânticos de PbTe do tipo p

Abstract

In this work, the properties of electric transport and the Rashba effect were investigated in p type PbTe / Pb0.9Eu0.1Te quantum wells, with and without BaF2 doping, with 10nm thickness. The measurements were carried out in the temperature range from 1.9K to 40K, using a blue LED with a wavelength of 460 nm and intensity of 276 mW / m². In magnetoresistance measurements for the doped sample, with and without illumination, we observed that for values below B ~ 4 T there are no significant oscillations at any measured temperature, but above B ~ 4 T there are oscillations at lower temperatures in the range of 1.9 K at 10K and for temperatures above 15 K the oscillations become evident in B ~ 7 T. The concentration of carriers and their mobility were also analyzed for the sample at temperature of 4.2 K, which showed a minimal decrease in the concentration of carriers and an increase in mobility when illuminated. The magnetoresistance measurements for the doped sample, with and without illumination, showed oscillations from B ~ 4 T for temperatures in the range of 1.9 K to 15 K and for temperatures above 20 K the oscillations are very discrete above B ~ 7 T. Without light, the oscillations of the undoped sample are composed of two oscillatory components and when illuminated, they are composed of three components with very different frequencies. At temperature of 6 K, the non-doped sample showed an increase in the concentration of carriers and a decrease in mobility when illuminated. The effective cyclotronic masses and the Landé g factor were also obtained for the samples. The analysis of the frequencies found indicates the Rashba effect (or SO). The doped sample showed a greater splitting Rasba of ellipsoids than the non-doped sample, reaching 50%. The energy of Rashba found for the doped sample was 13 meV.