Ballistic Electron Emission Spectroscopy of Heterostructures Using Metal and Degenerately-Doped Semiconductor Tips

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9313610 Narayanamurti A unique variable temperature, ultra high vacuum (UHV) compatible Ballistic Electron Emission Microscope (BEEM) apparatus is currently under development in the PI's laboratory. This exploratory proposal is directed at fabricating tips for the BEEM to perform spectroscopy on quantum semiconductor heterostructures and superlattices. Properly prepared, heavily doped, semiconductor tips should cause a sharply focused and monoenergetic beam of electrons or holes to be injected into the sample under study. The ability to perform variable temperature UHV studies using BEEM spectroscopy could lead to the observation of quantum mechanical tunneling and interface reflection effects, local determination of dopant density, minority carrier mean free paths, and single particle charging effects (Coulomb blockade regime) with possibly the first studies of discrete light emission from the dimensionally confined pn junction. Development of this technique will be particularly important for the spectroscopic study of dimensionally small systems such as nano-scale wires, quantum dots, resonant tunneling devices and narrow bandgap infrared detectors. %%% A unique variable temperature, ultra high vacuum (UHV) compatible Ballistic Electron Emission Microscope (BEEM) apparatus is currently under development in the PI's laboratory. This exploratory proposal is directed at fabricating probes for the BEEM to perform spectroscopy on complex semiconductor structures. Properly prepared, heavily doped, semiconductor probes should cause a sharply focused and monoenergetic beam of electrons or holes to be injected into the sample under study. The ability to perform variable temperature UHV studies using BEEM spectroscopy would provide valuable physical measurements and could lead to a better understanding of the electronic states in so-called quantum dots and semiconductor heterostructures and superlattices. It is clear that such studies become increasingly important as characteristic dimensions of semiconductor devices approach the nano-meter scale regime. ***