Semiconductor nanowires are promising candidates for future nanoelectronic devices. Integration of functional materials into nanowires in the form of nanowire heterostructures can give them unique properties and novel device applications. This thesis deals with the synthesis, characterization and electronic application of core/shell nanowire heterostructures. First, a novel approach to the core/shell heterostructure, namely the atomic layer deposition (ALD) is introduced to deposit high-dielectric-constant (high-k) oxide, perovskite oxide and metal. The excellent conformality of ALD allows these materials to form uniform shells on semiconductor nanowire cores. The electrical and magnetic properties of Si/ZrO₂/Ni core/shell/shell nanowires are further investigated, which shows metallic conductivity and axial alignment in a magnetic field.

Next, we study the performance of semiconductor/high-k-oxide core/shell nanowires as nanowire field effect transistors (NW-FETs). The fabrication strategies are first evaluated. Then high-performance NW-FET devices with large ON/OFF ratio, sharp switching and low leakage current are demonstrated. These devices show significant gate enhancement compared to the back-gated devices and are promising to outperform state-of-the-art planar MOSFETs fabricated with top-down methods.

Subsequently, a charge-trapping nanowire (CTNW) with semiconductor/multidielectric core/shell heterostructure is demonstrated. Charge-trapping in the nanowire heterostructure gives it memory function with large ON/OFF ratio and reliable switching. Charge-trapping also defines the gate response of the CTNW-FET, making it a programmable logic unit. Furthermore, the application of the CTNW heterostructure in neuromorphic circuit is investigated.

CTNWs are then built into crossbar array architecture to carry out complex functions. Programming different active node patterns into the array allows it to carry out different logic operations such as XOR, adder, subtractor and latch. These results show significant progress in the complexity of nanowire electronics, and demonstrate the great versatility of the CTNW crossbar array.

Lastly, semiconductor/ferroelectric nanowire heterostructure is investigated for its application in nanoscale memories. Si/ZrO₂/BaTiO₃ core/shell/shell nanowire shows polarization-modulated conductance and the nanowire ferroelectric FET (NW-FeFET) shows excellent memory characteristics such as >10⁶ ON/OFF ratio, 100ns switching and week-long stability. The down-scaling of the device is also studied, and shows great potential towards high-density information storage.