Band discontinuity and band gap of MBE grown HgTe/CdTe(001) heterointerfaces studied by k-resolved photoemission and inverse photoemission

We have investigated the valence band offset (Delta E-VBO) of the molecular beam epitaxially grown heterostructure HgTe/CdTe(001) by k-resolved ultrav iolet (UPS) and X-ray (XPS) photoemission. Our angle-dependent UPS measurem ents at two different photon energies demonstrate that the dispersion of th e valence band (VB) must be checked carefully in order to find the true pos ition of the VB maximum in the Brillouin zone. With this information the va lence band discontinuity was determined as (0.53 +/- 0.03) eV, which is dif ferent from previously found photoemission values but now agrees well with magneto-optical investigations. Tn addition, we have determined the energy gap of CdTe(001) and HgTe(001) by a combination of UV and inverse photoemis sion. The energy gap of CdTe is determined to (1.57 +/- 0.06) eV and that f or HgTe as (0.0 +/- 0.06) eV. We therefore conclude that HgTe is a semi-met al with inverted band structure in agreement with other results.