Silicon Nanowire Field-Effect Transistor as Label-Free Detection of Hepatitis B Virus Proteins with Opposite Net Charges.

The prevalence of hepatitis B virus (HBV) is a global healthcare threat, particularly chronic hepatitis B (CHB) that might lead to hepatocellular carcinoma (HCC) should not be neglected. Although many types of HBV diagnosis detection methods are available, some technical challenges, such as the high cost or lack of practical feasibility, need to be overcome. In this study, the polycrystalline silicon nanowire field-effect transistors (pSiNWFETs) were fabricated through commercial process technology and then chemically functionalized for sensing hepatitis B virus surface antigen (HBsAg) and hepatitis B virus X protein (HBx) at the femto-molar level.

Single-Molecule Ex Situ Atomic Force Microscopy Allows Detection of Individual Antibody-Antigen Interactions on a Semiconductor Chip Surface.

Although in situ atomic force microscopy (AFM) allows single-molecule detection of antibody-antigen binding, the practical applications of in situ AFM for disease diagnosis are greatly limited, due to its operational complexity and long operational times, including the execution time for the surface chemical/biological treatments in the equipped glass liquid cell. Herein, a method of graphically superimposed alignment that enables ex situ AFM analysis of an immobilized antibody at the same location on a semiconductor chip surface before and after incubation with its antigen is presented. All of the required chemical/biological treatments are executed feasibly using standard laboratory containers, allowing single-molecule ex situ AFM detection to be conducted with great practicality, flexibility, and versatility.

Probing the photovoltaic properties of Ga-doped CdS-CuS core-shell heterostructured nanowire devices.

In this study Ga-doped cadmium sulfide (CdS) nanowires (NWs) were grown through chemical vapor deposition. The carrier conductivities of the CdS NWs improved after the incorporation of Ga; moreover, the conductivities of the CdS NWs increased upon increasing the amount of the Ga source. Using a cation exchange method, these CdS NWs served as the source material for the preparation of Cu2S-CdS p-n heterostructured NWs.

Time-evolution of the electrical characteristics of MoS field-effect transistors after electron beam irradiation.

As the feature sizes of devices decrease to the nanoscale, electron microscopy and lithography will become increasingly essential techniques for fabrication and inspection. In this study, we probed the memory effects of MoS2 field-effect transistors (FETs) subjected to electron beam (e-beam) irradiation; after fabricating the devices on 300 nm SiO2/Si substrates, we irradiated the MoS2 FETs with various doses of irradiation from a 30 kV e-beam. The threshold voltage shifted to the negative side and the mobility increased-a so-called memory effect-upon increasing the e-beam dose.

Low-temperature-grown p-n ZnO nanojunction arrays as rapid and self-driven UV photodetectors.

In this study p-type ZnO nanorod (NR) arrays were grown using a low-temperature hydrothermal method in the presence of various concentrations of Sb in the doping solution. X-ray photoelectron spectroscopy revealed the atomic percentages and chemical states of the Sb dopant atoms in the p-type ZnO NR arrays. Photoluminescence and electrical measurements confirmed the p-type characteristics of the Sb-doped ZnO NR arrays.

Ionic screening effect on low-frequency drain current fluctuations in liquid-gated nanowire FETs.

The ionic screening effect plays an important role in determining the fundamental surface properties within liquid-semiconductor interfaces. In this study, we investigated the characteristics of low-frequency drain current noise in liquid-gated nanowire (NW) field effect transistors (FETs) to obtain physical insight into the effect of ionic screening on low-frequency current fluctuation. When the NW FET was operated close to the gate voltage corresponding to the maximum transconductance, the magnitude of the low-frequency noise for the NW exposed to a low-ionic-strength buffer (0.

Quantifying the barrier lowering of ZnO Schottky nanodevices under UV light.

In this study we measured the degrees to which the Schottky barrier heights (SBHs) are lowered in ZnO nanowire (NW) devices under illumination with UV light. We measured the I-V characteristics of ZnO nanowire devices to confirm that ZnO is an n-type semiconductor and that the on/off ratio is approximately 10(4). From temperature-dependent I-V measurements we obtained a SBH of 0.

Selective growth of ZnO nanorods on hydrophobic Si nanorod arrays.

In this paper we describe the selective growth of ZnO nanorods (NRs) on top of hydrophobic Si NR arrays. The periodic Si NR arrays, prepared through electroless chemical etching and HF treatment, functioned as hydrophobic substrates. Droplets containing ZnO seeds could be positioned on the Si NR arrays, causing the ZnO seeds to deposit selectively upon them, with n-ZnO NR/p-Si NR array heterojunctions ultimately forming after hydrothermal growth of ZnO NRs.

Low-frequency electrical fluctuations in metal-nanowire-metal phototransistors.

Using low-frequency noise spectroscopy to explore the physical origins of electrical fluctuations in ZnO nanowire (NW) phototransistors featuring a metal-NW-metal configuration, we have found that bulk mobility scatterings gave rise to electrical fluctuations in the low-gate voltage (V G) regime, providing values of Hooge's constant in the ranges 6.0-9.6 × 10(-3) and 1.

Measurement of in-plane displacement by wavelength-modulated heterodyne speckle interferometry.

The use of wavelength-modulated light incorporated into an optical-path-difference speckle interferometer is demonstrated as a heterodyne technique for measuring the in-plane displacement of a rough object. The in-plane displacement can be determined from the measured phase variation of the heterodyne speckle signal. We also improved the optical configuration to create a high-contrast interference pattern.

Near UV LEDs made with in situ doped p-n homojunction ZnO nanowire arrays.

Catalyst-free p-n homojunction ZnO nanowire (NW) arrays in which the phosphorus (P) and zinc (Zn) served as p- and n-type dopants, respectively, have been synthesized for the first time by a controlled in situ doping process for fabricating efficient ultraviolet light-emitting devices. The doping transition region defined as the width for P atoms gradually occupying Zn sites along the growth direction can be narrowed down to sub-50 nm. The cathodoluminescence emission peak at 340 nm emitted from n-type ZnO:Zn NW arrays is likely due to the Burstein-Moss effect in the high electron carrier concentration regime.

Probing the sensitivity of nanowire-based biosensors using liquid-gating.

We have used liquid-gating to investigate the sensitivity of nanowire (NW)-based biosensors for application in the field of ultrasensitive biodetection. We developed an equivalent capacitance model of the biosensor system to explore the dependence of the sensitivity on the liquid-gate voltage (V(lg)), which was influenced by capacitive competition between the NW capacitance and the thin oxide capacitance. NW biosensors with highest sensitivity were obtained when we operated the device in the subthreshold regime while applying an appropriate value of V(lg); the influence of leakage paths through the ionic solutions led, however, to significant sensitivity degradation and narrowed the operating window in the subthreshold regime.

ZnO-ZnS heterojunction and ZnS nanowire arrays for electricity generation.

Vertically aligned ZnO-ZnS heterojunction nanowire (NW) arrays were synthesized by thermal evaporation in a tube furnace under controlled conditions. Both ZnO and ZnS are of wurtzite structure, and the axial heterojunctions are formed by epitaxial growth of ZnO on ZnS with an orientation relationship of [0001](ZnO)//[0001](ZnS). Vertical ZnS NW arrays have been obtained by selectively etching ZnO-ZnS NW arrays.

Piezoelectric nanogenerator using p-type ZnO nanowire arrays.

Using phosphorus-doped ZnO nanowire (NW) arrays grown on silicon substrate, energy conversion using the p-type ZnO NWs has been demonstrated for the first time. The p-type ZnO NWs produce positive output voltage pulses when scanned by a conductive atomic force microscope (AFM) in contact mode. The output voltage pulse is generated when the tip contacts the stretched side (positive piezoelectric potential side) of the NW.