Imaging and spectroscopy of defects in semiconductors using aberration-corrected STEM

Abstract The distribution of single dopant or impurity atoms can dramatically alter the properties of semiconduc-tor materials. The sensitivity to detect and localize such sin-gle atoms has been greatly improved by the development of aberration correctors for scanning transmission electron mi-croscopes. Today, electron probes with diameters well be-low 1 Å are available thanks to the improved electron op-tics. Simultaneous acquisition of image signals and electron energy-loss spectroscopy data provides means of charac-terization of defect structures in semiconductors with un-precedented detail. In addition to an improvement of the lat-eral spatial resolution, depth sensitivity is greatly enhanced because of the availability of larger probe forming angles. We report the characterization of an alternate gate dielec-tric interface structure. Isolated Hf atoms are directly im-aged within a SiO2 thin film formed between an HfO2 layer and the silicon substrate. Electron energy-loss spectroscopy shows significant changes of the silicon valence state across the interface structure