Manifestation of the Transition Semiconductor-Semimetal and Intrinsic Interface State in Band Structure and Magneto-Transport Properties in Nanostructure Superlattice

摘要

We report here G carrier's magneto-transport properties and the band structure results for II-VI semiconductors. HgTe is a zero gap semiconductor and when it is sandwiched between CdTe layers yield a small gap HgTe/CdTe superlattice which is the key to development 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(k_z) and E(k_p), 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 cm~2/V·s. A reversal of the sign of the weak-field Hall coefficient occurs at 25 K with an electron mobility of 3 × 10~4 cm~2/V·s. In the intrinsic regime, the measured E_g ≈ 38 meV agrees with the calculated E_g(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.