| Popis: |
Results for the valence-band-edge offset (ΔEv) are reported for PbSe/Pb1−xEuxSe (x = 0.013) and PbTe/Pb1−xEuxTeSe (x = 0.026) heterojunctions in the temperature range of 77 to 300 K. The electron-beam-induced current, generated at a forward biased junction, was used to determine the built-in voltage. Both systems show a strong temperature dependence of the band-edge offset. PbSe/PbEuSe: ΔEv (300 K) = 7 meV (Type I), ΔEv (150 K) = −79 meV (Type I′). PbTe/PbEuTeSe: ΔEv (300 K) = = 80 meV, ΔEv (150 K) = 35 meV. Although this appears to be the first reported case of such a behaviour, the strong temperature dependence of the band gaps in IV–VI compounds makes such a shift a plausible one. While the error margin for the absolute values is estimated to be ±30 meV, it is less for their shift with temperature. |
