Band-edge offsets in PbSePbEuSe and PbTePbEuTeSe heterostructures deduced from electron-beam-induced current

Abstract Results for the valence-band-edge offset ( Δ E v ) are reported for PbSe/Pb 1−x Eu x Se (x = 0.013) and PbTe/Pb 1−x Eu x TeSe (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: Δ E v (300 K) = 7 meV (Type I), Δ E v (150 K) = −79 meV (Type I′). PbTe/PbEuTeSe: Δ E v (300 K) = = 80 meV, Δ E v (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.