Anisotropic Magneto-conductance of InAs Nanowire: Angle Dependent Suppression of 1D Weak Localization

The magneto-conductance of an InAs nanowire is investigated with respect to the relative orientation between external magnetic field and the nanowire axis. It is found that both the perpendicular and the parallel magnetic fields induce a positive magneto-conductance. Yet the parallel magnetic field induced longitudinal magneto-conductance has a smaller magnitude. This anisotropic magneto-transport phenomenon is studied as a function of temperature, magnetic field strength and at an arbitrary angle between the magnetic field and the nanowire. We show that the observed effect is in quantitative agreement with the suppression of one-dimensional (1D) weak localization

Impact of Short-Range Scattering on the Metallic Transport of Strongly Correlated 2D Holes in GaAs Quantum Wells

Understanding the non-monotonic behavior in the temperature dependent resistance, R(T), of strongly correlated two-dimensional (2D) carriers in clean semiconductors has been a central issue in the studies of 2D metallic states and metal-insulator-transitions. We have studied the transport of high mobility 2D holes in 20nm wide GaAs quantum wells (QWs) with varying short-range disorder strength by changing the Al fraction x in the Al_xGa_{1-x}As barrier. Via varying the short range interface roughness and alloy scattering, it is observed that increasing x suppresses both the strength and characteristic temperature scale of the 2D metallicity, pointing to the distinct role of short-range versus long-range disorder in the 2D metallic transport in this correlated 2D hole system with interaction parameter r_s~ 20.Comment: accepted for publication in Phys Rev

Frequency domain detection of biomolecules using silicon nanowire biosensors,”

ABSTRACT We demonstrate a new protein detection methodology based upon frequency domain electrical measurement using silicon nanowire field-effect transistor (SiNW FET) biosensors. The power spectral density of voltage from a current-biased SiNW FET shows 1/f-dependence in frequency domain for measurements of antibody functionalized SiNW devices in buffer solution or in the presence of protein not specific to the antibody receptor. In the presence of protein (antigen) recognized specifically by the antibodyfunctionalized SiNW FET, the frequency spectrum exhibits a Lorentzian shape with a characteristic frequency of several kilohertz. Frequency and conventional time domain measurements carried out with the same device as a function of antigen concentration show more than 10-fold increase in detection sensitivity in the frequency domain data. These concentration-dependent results together with studies of antibody receptor density effect further address possible origins of the Lorentzian frequency spectrum. Our results show that frequency domain measurements can be used as a complementary approach to conventional time domain measurements for ultrasensitive electrical detection of proteins and other biomolecules using nanoscale FETs. KEYWORDS Nanowire, FET, biosensor, frequency domain, Lorentzian O ne-dimensional nanostructures such as semiconducting nanowires (NWs) 1 have become a focus of intensive research due to their demonstrated potential for realizing a range of well-defined nanoscale devices for electronics, 2 photonics, 3 and biosensors. 11 The high surface-to-volume ratio and tunable carrier density in SiNW and other NW FETs make them sensitive probes of surface interactions, in particular, binding and unbinding of biomolecules as shown in Specifically, the frequency domain spectrum of a twolevel fluctuator system has the form of a Lorentzian function similar to that of a RC circuit. In this context, the population * To whom correspondence should be addressed, [email protected] and [email protected]. pubs.acs.org/NanoLet