1.Dept of Physics,Shanghai University;2.Shanghai Institute of Technique Physics, Chinese Academy of Sciences;3.中国科学院上海技术物理研究所;4.Physics Dept. Shanghai University
National natural science foundation
The cross-sectional scanning tunneling microscopy (XSTM) technique was used to study the cleaved surface of Hg0.72Cd0.28Te grown by molecular beam epitaxy. Scanning tunnel spectroscopy (STS)’s measurements show that the width of zero current plateau (the apparent tunneling gap) of current-voltage (I/V) spectra is about 130% larger than the practical band gap of the material, implying the existence of obvious tip-induced band bending (TIBB) effect with the measurement. Based on the 3D TIBB model, the STS data can however be interpreted and the calculated I/V spectra are in good agreement with the measurement. Nevertheless, certain deviation appears for those I/V data which were acquired with a large imaging bias, e.g. 1.6 V. This is because the current TIBB model does not taken into account the transport mechanism of the material itself, for which the band-to-band tunneling, trap assisted tunneling etc. could be non-negligible factors for the tunneling.