ELECTRON-BEAM-INDUCED CURRENT AND SCANNING TUNNELING SPECTROSCOPY CORRELATIVE STUDY OF CDXHG1-XTE AND CDTE CRYSTALS

A combined scanning electron microscope-scanning tunnelling microscope (SEM-STM) system has been used to characterize CdxHg1-xTe and CdTe cr ystals, The electron beam induced current (EBIC) mode of the SEM shows the existence of inhomogeneities in the electronic behaviour of the s amples, mainly related to the presence of subgrain boundaries and prec ipitates. Current imaging tunnelling spectroscopy images and the relat ed normalized differential conductance curves, obtained with the STM, reveal the electronic inhomogeneities at a finer scale. In particular, local variations of the band gap were shown by the conductance curves in regions with strong EBIC contrast. SEM-and STM-based techniques in a combined instrument appear to be complementary characterization tec hniques.