Temperature dependent investigation of the HgTe/CdTe valence band offset

We report here on a temperature dependent magneto-optical investigation of the valence band offset between HgTe and CdTe. The HI-E1 gap and the conduction band edge mass of various HgTe-(HgCd)Te superlattices were studied in a wide regime from liquid helium to nearly room temperature. With an offset of 550 meV which was determined previously at liquid helium temperatures and the temperature dependence of the F6-F s gap of bulk Hg]_xCdxTe, a nearly perfect description of the experimental data was obtained. Our experiment provides strong evidence that a temperature dependence of the band offset can essentially be neglected. A reliable prediction of the band structure of heterostructures based on Hgt_xCdxTe has not been possible until recently. Due to the uncertainty in the size of the valence band offset between the semimetal HgTe and the wide gap semiconductor CdTe, a quantitative comparison with experimental data was limited. The offsets determined at liquid helium temperatures from magneto-optical experiments scatter considerably between about 40 and 800 meV, and do not agree with the offset of 350 meV determined from X-ray (XPS) and ultraviolet photoelectron spectroscopy (UPS), as reviewed in Ref. [1]. The discrepancy between magneto-optical investigations and XPS and UPS experiments has not yet been resolved