Selective-area growth and transport properties of MnAs/InAs heterojunction nanowires

摘要

The authors summarize the results of selective-area growth of vertical MnAs/InAs heterojunction nanowire (NW) arrays and present a preliminary characterization of the transport properties of a single MnAs/InAs heterojunction NW and a single InAs host NW for MnAs inclusions. During the endotaxy of MnAs after the selective-area growth of host InAs nanowires (NWs) on partially SiO2-masked GaAs(111)B substrates, hexagonal NiAs-type MnAs nanoclusters (NCs), which exhibit spontaneous magnetization at room temperature, are formed with the direction oriented parallel to the B direction of the zinc-blende-type InAs host NWs. For InAs host NWs, a large positive ordinary magnetoresistance (MR) effect up to 165 is observed at temperatures between 7 and 280 K. In addition, magnetotransport measurements reveal universal conductance fluctuations and a weak Anderson localization at temperatures up to 20 K due to a charge-accumulation layer formed at the surface. Single MnAs/InAs heterojunction NWs, however, exhibit only a negative MR effect, which is independent of temperature T < 10 K and linearly decreases up to -10 at 10 T with increasing magnetic field. These results reveal the tremendous influence of ferromagnetic NCs on the transport behavior inside the InAs host NWs.