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 n ovel and interesting properties. It is well lattice matched to GaAs as well as ZnSe and therefore can be combined in superlattices with thes e materials. Using photoelectron spectroscopy we have investigated the valence-band offset (Delta E-v) of BeTe/ZnSe and BeTe/GaAs heterojunc tions, grown by molecular-beam epitaxy (MBE). For the BeTe/ZnSe hetero structure 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 de termined a far smaller valence-band offset of -0.25 +/- 0.15 eV. From UPS measurements for increasing layer thickness of BeTe on ZnSe we cal culated the accumulation layer of BeTe with a Debye-length of 6 nm and a defect concentration of 4.10(17) Cm-3. (C) 1998 Elsevier Science B. V. All rights reserved.