Photoelectron spectroscopy of molecular-beam epitaxially grown BeTe/ZnSe and BeTe/GaAs heterostructures

BeTe is a new material within the class of II–VI semiconductors with novel and interesting properties. It is well lattice matched to GaAs as well as ZnSe and therefore can be combined in superlattices with these materials. Using photoelectron spectroscopy we have investigated the valence-band offset (Δ E v ) of BeTe/ZnSe and BeTe/GaAs heterojunctions, grown by molecular-beam epitaxy (MBE). For the BeTe/ZnSe heterostructure with a Zn-rich interface, we measured a valence-band offset of 1.26±0.15 eV and for the heterovalent BeTe/GaAs interface we determined a far smaller valence-band offset of −0.25 ± 0.15 eV. From UPS measurements for increasing layer thickness of BeTe on ZnSe we calculated the accumulation layer of BeTe with a Debye-length of 6 nm and a defect concentration of 4.10 17 cm −3 .