Semiconductor nanowire (NWs) with unique physical and chemical properties have attracted great attention due to their promising applications in nanoelectronics including field effect transistors (FETs),diodes,gas sensors,etc.[1-3] These nanoelectronics are fabricated based on the metal-semiconductormetal (M-S-M) nanostructure or/and a metalsemiconductor (M-S) nanocontact and performed based on digital and/or analog circuits.Functionalities of these circuits are well understood to amplify or to switch electronic signals.High performance of the nanoelectronics significantly depends on the electrical transport properties of individual semiconductor NWs as well as M-S nanocontacts.Because the electrical transport properties of semiconductor NWs with very small diameter are dimensionally and microstructurally dependent,NWs with the same composition may possess dissimilar properties due to differences in their crystal phase,crystalline qualities,geometrical configurations including aspect ratios and the crystallographic orientation along the wire axis,and surface conditions such as morphological facets,contamination and oxidation.Some microscopic techniques with high special resolution,including scanning probe techniques such as scanning tunneling microscopy (STM),electrostatic force microscopic (EFM),scanning thermal microscopy (SThM)combined with atomic force microscopy (AFM),and electron microscopic techniques including transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have to be used for characterization of the microstructure and electrical transport properties of individual NWs.[4-7] Among these microscopic techniques,in situ TEM is the most powerful imaging tool to study both the microstructure at atomic resolution and transport property of vatious metallic and semiconductor NWs.