Research On The Assembly And Electrical Eharacteristics Of InAs Nanowire

Semiconductor nanowires (NWs) are promising building blocks for future photonic and electronic devices. Recently, NWs have attracted much attention because of their excellent properties, being successfully applied for biosensors, gas sensors, photo-detectors and other sensors manufacture. Specifically, when InAs NWs capped with a2nm InP shell, high electron mobility of1.15×104cm2V-1s-1can be obtained at room temperature.However, the relationship between shell thickness and transistor’s electron mobility and density has not yet been experimentally studied, which is of great importance in designing a NW transistor. In order to generalize the relationship, the paper mainly studies on the growth of InAs/InP core/shell NW, large-scale assembly and fabrication of single NW field-effect transistors (FET). Moreover, the effect of shell thickness on electrical characteristic of the transistor is experimentally investigated.Firstly, InAs/InP core/shell NWs with different shell thicknesses were grown by a two-step method. Shell thicknesses are0nm,0.9nm,5.4nm and18nm.Secondly, a NWs alignment method based on dielectrophoresis alignment and patterned grooves is presented for realizing large-scale assembly of single nanowire. Thousands of single nanowire field-effect transistors were fabricated on a single chip.Moreover, experiment was set up to test electrical characteristics of nanowire transistors, Experiment results shows that the mobility increases rapidly with a shell thickness increase from0nm to0.9nm, and then decreases with further increasing shell thickness. The electron density is monotonically decreased with increasing shell thickness.In the end, the paper summarizes the following conclusion. The InP shell can effectively reduce surface accumulated electrons and ionized-atoms by passivating the surface state of InAs NW. Thus, with the increase of shell thickness and surface passivation, the electron density is decreased and the electron mobility is increased via decreasing ionized-atom related scattering. However, when the shell thickness increases to5.4nm (larger than the critical thickness), misfit dislocations would be generated, which can result in a recombination center and local variation of strain, bandgap and potential. The recombination center and potential variation will reduce the electron mobility via trapping and scattering, respectively. Thus, the electron mobility is decreased with the further increase of InP shell thickness.