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As of yet, III-V p-type field-effect transistors (p-FETs) on Si have not been reported, due partly to materials and processing challenges, presenting an important bottleneck in the development of complementary III-V electronics. Here, we report the first high-mobility III-V p-FET on Si, enabled by the epitaxial layer transfer of InGaSb heterostructures with nanoscale thicknesses. Importantly, the use of ultrathin (thickness, ~2.5 nm) InAs cladding layers results in drastic performance enhancements arising from (i) surface passivation of the InGaSb channel, (ii) mobility enhancement due to the confinement of holes in InGaSb, and (iii) low-resistance, dopant-free contacts due to the type III band alignment of the heterojunction. The fabricated p-FETs display a peak effective mobility of ~820 cm(2)/(V s) for holes with a subthreshold swing of ~130 mV/decade. The results present an important advance in the field of III-V electronics., (© 2012 American Chemical Society)

Nanowires have unique optical properties and are considered as important building blocks for energy harvesting applications such as solar cells. However, due to their large surface-to-volume ratios, the recombination of charge carriers through surface states reduces the carrier diffusion lengths in nanowires a few orders of magnitude, often resulting in the low efficiency (a few percent or less) of nanowire-based solar cells. Reducing the recombination by surface passivation is crucial for the realization of high-performance nanosized optoelectronic devices but remains largely unexplored. Here we show that a thin layer of amorphous silicon (a-Si) coated on a single-crystalline silicon nanowire, forming a core-shell structure in situ in the vapor-liquid-solid process, reduces the surface recombination nearly 2 orders of magnitude. Under illumination of modulated light, we measure a greater than 90-fold improvement in the photosensitivity of individual core-shell nanowires, compared to regular nanowires without shell. Simulations of the optical absorption of the nanowires indicate that the strong absorption of the a-Si shell contributes to this effect, but we conclude that the effect is mainly due to the enhanced carrier lifetime by surface passivation.

In order to record multi-site electroretinogram (ERG) responses in isolated carp retinae, we utilized three-dimensional (3D), extracellular, 3.5-μm-diameter silicon (Si) probe arrays fabricated by the selective vapor-liquid-solid (VLS) growth method. Neural recordings with the Si microprobe exhibit low signal-to-noise (S/N) ratios of recorded responses due to the high-electrical-impedance characteristics of the small recording area at the probe tip. To increase the S/N ratio, we designed and fabricated enlarged gold (Au) tipped Si microprobes (10-μm-diameter Au tip and 3.5-μm-diameter probe body). In addition, we demonstrated that the signal attenuation and phase delay of ERG responses recorded via the Si probe can be compensated by the inverse filtering method. We conclude that the reduction of probe impedance and the compensation of recorded signals are useful approaches to obtain distortion-free recording of neural signals with high-impedance microelectrodes., (Copyright © 2010 Elsevier B.V. All rights reserved.)

We report here a technique for use in electrical interfaces between neurons and microelectronics, using vertically integrated silicon probe arrays with diameters of 2-3.5 microm and lengths of 60-120 microm. Silicon probe arrays can be fabricated by selective vapor-liquid-solid (VLS) growth. A doped n-type silicon probe with the resistance of 1 k Omega has an electrical impedance of less than 10 M Omega in physiological saline. After inserting the probe arrays into the retina of a carp (Cyrpinus carpio), we conducted electrical recording of neural signals, using the probes to measure light-evoked electrical neural signals. We determined that recorded signals represented local field potentials of the retina (electroretinogram (ERG)). The VLS-probe can provide minimally invasive neural recording/stimulation capabilities at high spatial resolution for fundamental studies of nervous systems. In addition, the probe arrays can be integrated with microelectronics; therefore, these probes make it possible to construct interfaces between neurons and microelectronics in advanced neuroscience applications., ((c) 2010 Elsevier B.V. All rights reserved.)

This paper describes the fabrication of Si micro probe and SiO(2) micro tube array and their mechanical properties. The device is successfully fabricated with high-density array. One of the requirements of the penetrating device is to have the enough mechanical strength to be able to penetrate into the tissue. Hence mechanical properties are investigated and discussed using the results on bending obtained by experiments and simulation of finite element method. The device was penetrated by simple in-vitro experiments using a gelatin.

Over the past several years, the inherent scaling limitations of silicon (Si) electron devices have fuelled the exploration of alternative semiconductors, with high carrier mobility, to further enhance device performance. In particular, compound semiconductors heterogeneously integrated on Si substrates have been actively studied: such devices combine the high mobility of III-V semiconductors and the well established, low-cost processing of Si technology. This integration, however, presents significant challenges. Conventionally, heteroepitaxial growth of complex multilayers on Si has been explored-but besides complexity, high defect densities and junction leakage currents present limitations in this approach. Motivated by this challenge, here we use an epitaxial transfer method for the integration of ultrathin layers of single-crystal InAs on Si/SiO2 substrates. As a parallel with silicon-on-insulator (SOI) technology, we use 'XOI' to represent our compound semiconductor-on-insulator platform. Through experiments and simulation, the electrical properties of InAs XOI transistors are explored, elucidating the critical role of quantum confinement in the transport properties of ultrathin XOI layers. Importantly, a high-quality InAs/dielectric interface is obtained by the use of a novel thermally grown interfacial InAsOx layer (~1 nm thick). The fabricated field-effect transistors exhibit a peak transconductance of ~1.6 mS µm−1 at a drain-source voltage of 0.5 V, with an on/off current ratio of greater than 10,000. [ABSTRACT FROM AUTHOR]

Ultrathin-body InAsSb-on-insulator n-type field-effect transistors (FETs) with ultrahigh electron mobilities are reported. The devices are obtained by the layer transfer of ultrathin \InAs0.7\Sb0.3 layers (thickness of 7–17 nm) onto \Si/SiO2 substrates. InAsSb-on-insulator FETs exhibit an effective mobility of \sim\!\!\3400\ \cm^2/\V\cdot \s for a body thickness of 7 nm, which represents \sim\! \!\2\times enhancement over InAs devices of similar thickness. The top-gated FETs deliver an intrinsic transconductance of \sim\!\!\0.56\ \mS/\mu\m (gate length of \sim500 nm) at VDS = \0.5\ \V with ION/IOFF of \10^2–\10^3. These results demonstrate the utility of the transfer process for obtaining high-mobility n-FETs on Si substrates by using mixed anion arsenide–antimonide as the active channel material. [ABSTRACT FROM AUTHOR]

This paper reports the radio frequency (RF) performanceof InAsnanomembrane transistors on both mechanically rigid and flexible substrates.We have employed a self-aligned device architecture by using a T-shapedgate structure to fabricate high performance InAs metal-oxide-semiconductorfield-effect transistors (MOSFETs) with channel lengths down to 75nm. RF measurements reveal that the InAs devices made on a siliconsubstrate exhibit a cutoff frequency (ft) of ∼165 GHz, which is one of the best results achieved inIII–V MOSFETs on silicon. Similarly, the devices fabricatedon a bendable polyimide substrate provide a ftof ∼105 GHz, representing the best performance achievedfor transistors fabricated directly on mechanically flexible substrates.The results demonstrate the potential of III–V-on-insulatorplatform for extremely high-frequency (EHF) electronics on both conventionalsilicon and flexible substrates. [ABSTRACT FROM AUTHOR]