Correlation Between Band Structure and Magneto- Transport Properties in HgTe/CdTe Two-Dimensional Far-Infrared Detector Superlattice

Theoretical calculations of the electronic properties of n -type HgTe/CdTe superlattices (SLs) have provided an agreement with the experimental data on the magneto-transport behaviour. We have measured the conductivity, Hall mobility, Seebeck and Shubnikov-de Haas effects and angular dependence of the magneto-resistance. Our sample, grown by MBE, had a period d = d 1 + d 2 (124 layers) of . Calculations of the spectras of energy E ( d 2 ), E ( k z ) and E ( k p ), respectively, in the direction of growth and in plane of the superlattice; were performed in the envelope function formalism. The energy E ( d 2 , Γ ,4.2 K), shown that when d 2 increase the gap E g decrease to zero at the transition semiconductor to semimetal conductivity behaviour and become negative accusing a semimetallic conduction. At 4.2 K, the sample exhibits n type conductivity, confirmed by Hall and Seebeck effects, with a Hall mobility of . This allowed us to observe the Shubnikov-de Haas effect with n =3.20×10 12 cm −2 . Using the calculated effective mass ( ) of the degenerated electrons gas, the Fermi energy (2D) was E F =88 meV in agreement with 91 meV of thermoelectric power α . In intrinsic regime, α ∼ T −3/2 and R H T 3/2 indicates a gap E g = E 1 − HH 1 =101 meV in agreement with calculated E g ( Γ ,300 K)=105 meV. The formalism used here predicts that the system is semiconductor for d 1 / d 2 =2.69 and d 2