Moroccan Journal of Condensed Matter, Vol 12, No 1 (2010)

Correlation between band structure and magneto-transport properties in far-infrared detector modulated nanostructures superlattice

R. Morghi, A. Nafidi, M. Braigue, H. Chaib, J. Hemine, A. Tirbiyine, B. Er-Raha, M. Garcia Enrique, M. D'Astuto

Abstract


We report here carrier’s magneto-transport properties and the band structure results for II-IV semiconductors. HgTe is a zero gap semiconductor when it is sandwiched between CdTe layers to yield to a small gap HgTe/CdTe superlattice which is the key of an infrared detector. Our sample, grown by MBE, had a period d (100 layers) of 18 nm (HgTe) / 4.4 nm (CdTe). Calculations of the spectra of energy E(kz) and E(kp), respectively, in the direction of growth and in the plane of the superlattice were performed in the envelope function formalism. The angular dependence of the transverse magnetoresistance follows the two-dimensional (2D) behavior with Shubnikov-de Haas oscillations. At low temperature, the sample exhibits p type conductivity with a hole mobility of 900 cm²/V.s. A reversal the sign of the weak-field Hall coefficient occurs at 25 K with an electron mobility of 3 104 cm2/Vs. In intrinsic regime, the measured Eg ≈ 38 meV agrees with calculated Eg(Γ,300 K) = 34 meV which coincide with the Fermi level energy. The formalism used here predicts that this narrow gap sample is semi metallic, quasi-two-dimensional and far-infrared detector.