Nemanja Peric
Charge injection in semiconductor nanowires
Institut supérieur de l'électronique et du numérique
Engineering the properties of electrical contacts relies on a detailed understanding of the physical mechanisms of charge injection, which govern charge transport across metal-semiconductor interfaces. For semiconductor nanowires (NW), whose crystal structure, Fermi level pinning at surfaces and binding energies of impurities depart from bulk materials, this must be systematically re-evaluated to realize high-performance contacts using conventional metals or transparent conductive electrodes. To improve our fundamental understanding of the electrical contact to (semiconductor) nanowires, I will be involved in the study of nanowires with single and multiple probe scanning tunneling microscopy in ultrahigh vacuum at variable temperatures. The use of multi-probe scanning tunneling microscope will enable the arbitrary positioning of four probes on complex heterostructured nanowires (as presented in Figure 1). Such setup should help in improving the contact formation between nanowires and electrodes.
Figure 1. SEM image of free-standing InAs NWs grown on an InP(111)B substrate. The NW in the center is contacted with four W tips, that are used either as sourcing electrodes or potential probes. The electron beam energy is 5 keV. Scale bar: 150 nm. (Durand et al., 2013)
Detailed information of the nanowire surfaces will be relevant to understand the atomistic processes that may occur on the sidewalls during the formation of electrical contacts to the nanowires. Nanoscale characterization of band alignment and physical description of charge transport mechanisms through metal-semiconductor interfaces will be performed to optimize charge injection between NWs and metallic electrodes. In collaboration with companies, tools will be developed to study (i) the dynamics of charge carriers in the vicinity of metal/semiconductor interfaces and (ii) the local strain/doping induced in the semiconductor by the formation of a metallic contact.
Durand, C., Berthe, M., Makoudi, Y., Nys, J.-P., Leturcq, R., Caroff, P., Bruno Grandidier, 2013. Persistent enhancement of the carrier density in electron irradiated InAs nanowires. Nanotechnology 24, 275706. https://doi.org/10.1088/0957-4484/24/27/275706
