Burstein-Moss Effect of PbTe-Pb1-xSnxTe Superlattice

Abstract
Optical-absorption-edge shifts due to free carrier (Burstein-Moss effect) of PbTe-Pb1-x Sn x Te (x=0.22) superlattices (SLs) were measured at 77 K to determine the band offset of the heterojunction. For the n-type SL, the shift was very small owing to the electron confinement into PbTe wider gap layers resulting from a type-I' band structure. On the other hand, a large shift was observed for the p-type SL owing to the electron confinement into Pb1-x Sn x Te narrower gap layers. Analyzing the optical absorption properties, conduction band edge of the Pb1-x Sn x Te was estimated to be 60 meV higher than that of PbTe.