Electron transport in multigate In x Ga 1-x as nanowire FETs: from diffusive to ballistic regimes at room temperature

The III-V semiconductors such as In x Ga 1-x As (x = 0.53-0.70) have attracted significant interest in the context of low power digital complementary metal-oxide-semiconductor (CMOS) technology due to their superior transport properties. However, top-down patterning of III-V semiconductor thin films into strongly confined quasi-one-dimensional (1D) nanowire geometries can potentially degrade the transport properties. To date, few reports exist regarding transport measurement in multigate nanowire structures. In this work, we report a novel methodology for characterizing electron transport in III-V multigate nanowire field effect transistors (NWFETs). We demonstrate multigate NWFETs integrated with probe electrodes in Hall Bridge geometry to enable four-point measurements of both longitudinal and transverse resistance. This allows for the first time accurate extraction of Hall mobility and its dependence on carrier concentration in III-V NWFETs. Furthermore, it is shown that by implementing parallel arrays of nanowires, it is possible to enhance the signal-to-noise ratio of the measurement, enabling more reliable measurement of Hall voltage (carrier concentration) and, hence, mobility. We characterize the mobility for various nanowire widths down to 40 nm and observe a monotonic reduction in mobility compared to planar devices. Despite this reduction, III-V NWFET mobility is shown to outperform state-of-the-art strained silicon NWFETs. Finally, we demonstrate evidence of room -temperature ballistic transport, a desirable property in the context of short channel transistors, in strongly confined III-V nanowire junctions using magneto-transport measurements in a nanoscale Hall-cross structure.