Strong intersubband absorption in EuTe/PbTe double-well superlattices at normal incidence

EuTe/PbTe double-well superlattices with two kinds of PbTe quantum wells separated by monolayer EuTe were prepared on KCI(100) substrates by hot wall epitaxy. Strong intersubband absorptions as high as 2000 cm(-1) in absorption coefficient were observed for n-type samples with a carrier concentration as high as 3x10(18)cm(-3) at normal incidence. The absorption was caused through the modulation of quantum-well potential along superlattice direction at L-point of the Brillouin zone. Temperature dependence of the optical transmission properties was also measured and the absorption peak showed a large tunability of 0.9cm(-1) K-1 caused by large temperature dependence of effective masses in PbTe.