W. I. Milne

University of Cambridge | Cam · Department of Engineering

With many thousands of different varieties to date, the nanowire (NW) library continues to grow at pace. With the continued and hastened maturity of nanotechnology, significant advances in materials science have allowed for the rational synthesis of a myriad of NW types of unique electronic and optical properties, allowing for the realization of a...

This work investigates a solution process for yttria-stabilized zirconia (YSZ) thin film deposition involving the addition of yttria nanoparticles, at 400 °C, in air. Different yttrium doping levels in the YSZ were studied and a wide range of optical, structural, surface, dielectric, and electronic transport properties were also investigated. An op...

A high density of silicon nanowires for solar cell applications was fabricated on a single crystalline silicon wafer, using low eutectic temperature metal catalysts, namely, gallium, indium, tin, and bismuth. The use of silicon nanowires is exploited for light trapping with an aim to enhance the efficiency of solar cells. Additionally, we have opti...

Thin film transistors (TFTs) based on metal oxide semiconductors have been attracting considerable attention over the last two decades as alternatives to a-Si due to their superior electrical performance coupled with optical transparency to visible light and mechanical flexibility. They have become highly desirable for applications in backplane ele...

Spray‐coated crystalline InZnOx‐based semiconductors are investigated as a function of [In3+]:[Zn2+] and their performance as TFTs semiconducting channels. More precisely, it is demonstrated that optical, structural, and electron transport properties show a high degree of sensitivity to the films' stoichiometry; that is, the [In3+]:[Zn2+] atomic ra...

The D- and G-band Raman signals from random arrays of vertically aligned, multi-walled carbon nanotubes are significantly enhanced (up to ~14x) while the signal from the underlying Si substrate is simultaneously attenuated (up to ~6x) when the nanotubes are dressed, either capped or coated, with Ag. These Ag-induced counter-changes originate with t...

With many thousands of different varieties to date, the nanowire (NW) library continues to grow at pace. With the continued and hastened maturity of nanotechnology, significant advances in materials science have allowed for the rational synthesis of a myriad of NW types of unique electronic and optical properties, allowing for the realisation of a...

Aluminum oxide (Al2O3) and hafnium oxide (HfO2) have been grown, using atomic layer deposition (ALD), as single and bi-layer gate dielectric films. Electrical and structural characterization indicates that the material properties depend on layer thickness and growth order, when deposited as bi-layers. Charge trapping at the interface between the bi...

In this study we report on the electron transport in flexible-transparent polymer supported chemically doped chemical vapour deposited (CVD) graphene. We investigate the modified carrier transport following doping with various metal chlorides. An increase in the work function was noted upon AuCl3, FeCl3, IrCl3, and RhCl3 doping, whilst only SnCl2 d...

Aluminium oxide (Al 2 O 3 ) and hafnium oxide (HfO 2 ) have been grown, using atomic layer deposition (ALD), as single and bi-layer gate dielectric films. Electrical and structural characterisation indicates that the material properties depend on layer thickness and growth order, when deposited as bi-layers. Charge trapping at the interface between...

The authors acknowledge support from the Innovative electronic Manufacturing Research Centre (IeMRC) through the EPSRC funded flagship project SMART MICROSYSTEMS (FS/01/02/10), Knowledge Transfer Partnership No KTP010548, EPSRC project EP/L026899/1, EP/F063865/1; EP/F06294X/1, EP/P018998/1, the Royal Society-Research Grant (RG090609) and Newton Mob...

Recently, piezoelectric thin films including zinc oxide (ZnO) and aluminium nitride (AlN) have found a broad range of lab-on-chip applications such as biosensing, particle/cell concentrating, sorting/patterning, pumping, mixing, nebulisation and jetting. Integrated acoustic wave sensing/microfluidic devices have been fabricated by depositing these...

This work reports on solution processed Nd2O3 thin films that are deposited under ambient conditions at moderate temperatures of about 400 °C and their implementation as gate dielectrics in thin film transistors employing solution processed ZnO semiconducting channels is also demonstrated. The optical, dielectric, electric, structural, surface, and...

A concurrently high beam current and high current density carbon nanotube (CNT) cold cathode electron gun is herein developed. A radial electron source has been realized, formed from CNTs synthesized directly on the side walls of a stainless steel truncated-cone electron gun. Experimental results evidenced a 35 kV/50 mA electron beam can achieve a...

Amorphous zinc tin oxides (a-ZTO), which are stoichiometrically close to the Zn2SnO4 and ZnSnO3 phases, have been deposited using remote-plasma reactive sputtering, and incorporated as the channel layers in thin film transistors (TFTs). The influence of tin composition and annealing temperatures on the structural and phase evolutions of the thin fi...

Amorphous zinc tin oxides (a-ZTO), which are stoichiometrically close to the Zn$_2$SnO$_4$ and ZnSnO$_3$ phases, have been deposited using remote-plasma reactive sputtering, and incorporated as the channel layers in thin film transistors (TFTs). The influence of tin composition and annealing temperatures on the structural and phase evolutions of th...

Here, we investigate, through parametrically optimized macroscale simulations, the field electron emission from arrays of carbon nanotube (CNT)-coated Spindts towards the development of an emerging class of novel vacuum electron devices. The present study builds on empirical data gleaned from our recent experimental findings on the room temperature...

Here, we investigate, through parametrically optimized macroscale simulations, the field electron emission from arrays of carbon nanotube (CNT)-coated Spindts towards the development of an emerging class of novel vacuum electron devices. The present study builds on empirical data gleaned from our recent experimental findings on the room temperature...

With the rapidly increasing demands for ultrasensitive biodetection, the design and applications of new nano-scale materials for development of sensors based on optical and electrochemical transducers have attracted substantial interest. In particular, given the comparable sizes of nanomaterials and biomolecules, there exist plenty of opportunities...

Suppression of the hysteretic electron emission in one-dimensional nanomaterial-based electron sources remains a critical barrier preventing their wide scale adoption in various vacuum electronics applications. Here, we report on the suppressed hysteretic performance, and its photo-dependence from conformal poly-vinylpyrrolidone encapsulated percol...

Silicon dioxide (SiO2) is the most widely used dielectric for electronic applications. It is usually produced by thermal oxidation of silicon or by using a wide range of vacuum-based techniques. By default, the growth of SiO2 by thermal oxidation of silicon, requires the use of Si substrates whereas the other deposition techniques either produce lo...

In this work we report on the fabrication of inductively coupled plasma (ICP) etched, diode-type, bulk molybdenum field emitter arrays. Emitter etching conditions as a function of etch mask geometry and process conditions were systematically investigated. For optimized uniformity, aspect ratios of >10 were achieved, with 25.5 nm-radius tips realise...

With the rapidly increasing demands for ultrasensitive biodetection, the design and applications of new nano-scale materials for development of sensors based on optical and electrochemical transducers have attracted substantial interest. In particular, given the comparable sizes of nanomaterials and biomolecules, there exist plenty of opportunities...

In this work we report on the fabrication of inductively coupled plasma (ICP) etched, diode-type, bulk molybdenum field emitter arrays. Emitter etching conditions as a function of etch mask geometry and process conditions were systematically investigated. For optimized uniformity, aspect ratios of >10 were achieved, with 25.5 nm-radius tips realise...

Suppression of the hysteretic electron emission in one-dimensional nanomaterial-based electron sources remains a critical barrier preventing their wide scale adoption in various vacuum electronics applications. Here we report on the suppressed hysteretic performance, and its photo-dependence from conformal poly-vinylpyrrolidone (PVP) encapsulated p...

The field emission (FE) properties of carbon nanotube (CNT)-based cathodes have been investigated on nanostructured surfaces grown by plasma enhanced chemical vapor deposition. The FE angular properties and temporal stability of the emergent electron beam have been determined using a dedicated apparatus for cathodes of various architectures and geo...

The field emission (FE) properties of carbon nanotube (CNT)-based cathodes have been investigated on nanostructured surfaces grown by plasma enhanced chemical vapor deposition. The FE angular properties and temporal stability of the emergent electron beam have been determined using a dedicated apparatus for cathodes of various architectures and geo...

The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizonta...

Electronic defect states at material interfaces provide highly deleterious sources of noise in solid-state nanostructures, and even a single trapped charge can qualitatively alter the properties of short one-dimensional nanowire field-effect transistors (FET) and quantum bit (qubit) devices. Understanding the dynamics of trapped charge is thus esse...

The influence of the stoichiometry of amorphous zinc tin oxide (a-ZTO) thin films used as the semiconducting channel in thin film transistors (TFTs) is investigated. A-ZTO has been deposited using remote-plasma reactive sputtering from zinc:tin metal alloy targets with 10%, 33%, and 50% Sn at. %. Optimisations of thin films are performed by varying...

The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizonta...

This study reports on a facile and widely applicable method of transferring chemical vapour deposited (CVD) graphene uniformly onto optically transparent and mechanically flexible substrates using commercially available, low cost ultra-violet adhesive (UVA) and hot-press lamination (HPL). We report the adhesion potential between the graphene and th...

Multi-beam modulation in a carbon nanotube (CNT) cold cathode electron gun is herein investigated in order to develop miniaturized and fully integrated vacuum electron devices. By exposing the electron source to a millimeter-wave signal, the steady-state field emission current density is efficiently modulated by the incident high-frequency (HF) ele...

In this study, we report on the development of a doping scheme for large-area chemical vapour deposited graphene transferred to optically transparent and mechanically flexible polymer supports. The temporal stability of the sheet resistance and optical transparency is presented following chemical doping with various metal chlorides (MexCly). The sh...

Here we report on a straightforward and rapid means of enhancing the field electron emission performance of nascent vertically aligned multi-walled carbon nanotubes by introducing a polar zwitterionic conjugated polyelectrolyte adlayer at the vacuum-emitter interface. We attribute the observed 66% decrease in turn-on electric field to the augmented...

Here we report on a straightforward and rapid means of enhancing the field electron emission performance of nascent vertically aligned multi-walled carbon nanotubes by introducing a polar zwitterionic conjugated polyelectrolyte adlayer at the vacuum–emitter interface. We attribute the observed 66% decrease in turn-on electric field to the augmented...

Examines the Low Resistivity, High Mobility, and Zero Bandgap of Graphene The Graphene Science Handbook is a six-volume set that describes graphene’s special structural, electrical, and chemical properties. The book considers how these properties can be used in different applications (including the development of batteries, fuel cells, photovoltai...

This paper reports on a simple approach for fabricating modest aspect ratio field emission arrays (FEAs) directly from bulk molybdenum substrates via the use of fluorine inductive-coupled-plasma (ICP) etching. Compared to traditional Spindt array fabrication, through our outlined fabrication process all thin film interfaces have been eliminated red...

The Graphene Science Handbook is a six-volume set that describes graphene’s special structural, electrical, and chemical properties. The book considers how these properties can be used in different applications (including the development of batteries, fuel cells, photovoltaic cells, and supercapacitors based on graphene) and produced on a massive a...

The Graphene Science Handbook is a six-volume set that describes graphene’s special structural, electrical, and chemical properties. The book considers how these properties can be used in different applications (including the development of batteries, fuel cells, photovoltaic cells, and supercapacitors based on graphene) and produced on a massive a...

Explores Chemical-Based, Non-Chemical Based, and Advanced Fabrication Methods The Graphene Science Handbook is a six-volume set that describes graphene’s special structural, electrical, and chemical properties. The book considers how these properties can be used in different applications (including the development of batteries, fuel cells, photovo...

Discover the Unique Electron Transport Properties of Graphene The Graphene Science Handbook is a six-volume set that describes graphene’s special structural, electrical, and chemical properties. The book considers how these properties can be used in different applications (including the development of batteries, fuel cells, photovoltaic cells, and...

Size Up the Short- and Long-Term Effects of Graphene The Graphene Science Handbook is a six-volume set that describes graphene’s special structural, electrical, and chemical properties. The book considers how these properties can be used in different applications (including the development of batteries, fuel cells, photovoltaic cells, and supercap...

In article 1500318, M. T. Cole and co‐workers empirically compare the field electron emission performance of bulk, 1D, and 2D nanomaterials in the largest metal‐analysis of its type. The turn‐on electric field and maximum current density show correlation with emitter dimensionality, confirming that high aspect ratios and highly perturbed surfaces a...

Carbon is an extremely promising material for cold cathode electron emission. The various carbon allotropes, in particular the graphic sp3 derivatives; the fullerenes and carbon nanotubes (CNTs), have been some of the most widely studied materials in the arena of field emission. Their low sputter coefficients, rapid temporal responses, low surface...

We introduce a comprehensive approach to the design of mirror-symmetry-broken terahertz (THz) metamaterials and present both the simulation and experimental results which show the desired asymmetric Fano resonances and electromagnetically induced transparency-like windows. With a full-wave simulation, we find these asymmetry-induced resonance modes...

Here we present the deposition of antimony-doped tin oxide thin films using the ambient spray pyrolysis technique and demonstrate their implementation as transparent electrodes (anodes) in red, green and blue Organic Light emitting diodes. The films were spray coated at 380 oC from SnCl4 and SbCl3 solution blends in methanol and ∽230 nm thick films...

The field electron emission performance of bulk, 1D, and 2D nanomaterials is here empirically compared in the largest metal-analysis of its type. No clear trends are noted between the turn-on electric field and maximum current density as a function of emitter work function, while a more pronounced correlation with the emitters dimensionality is not...

Cold cathode fi eld emission from nanomaterials is an on-going area of great academic and technological interest. There have been many suggested applications of fi eld electron emission, including displays, [ 1–3 ] traveling wave tubes, [ 4,5 ] microwave amplifi ers, [ 6,7 ] electron microscopy, [ 8,9 ] parallel electron beam lithography, [ 2,10,11...

Following the recent global excitement and investment in the emerging, and rapidly growing, classes of one and two-dimensional nanomaterials, we here present a perspective on one of the viable applications of such materials: field electron emission based x-ray sources. These devices, which have a notable history in medicine, security, industry and...

ZnO films with a c-axis significantly inclined away from the surface normal were grown by a remote plasma sputtering technique at room temperature. The films were used to make solidly mounted resonators (SMRs) operating in shear mode at a resonant frequency of 1.35 GHz. Control of the ZnO microstructure was achieved using a polycrystalline AlN seed...

A digital variable capacitor has been designed and fabricated based on multi-cantilevers of doped nanocrystalline silicon with variable lengths, suspended over a bottom electrode on top of a high-k material, HfO2, to increase the tuning range of the capacitance. By applying a voltage between the electrodes, the electrostatic force pulls the beams i...

The graphitic nanocarbon allotropes-namely, the fullerenes, graphene, and carbon nanotubes-have attracted significant attention from academia and industry given their useful and controllable optoelectronic properties. Here we provide an up-to-date overview of the growth, alignment, manufacture, and function of engineered carbon nanotube-based elect...

Metal nanostructures with conical shape, vertical alignment, large aspect ratio, controlled cone angle, and single-crystal structure are ideal candidates for enhancing field electron-emission efficiency with additional merits such as good mechanical and thermal stability. However, fabrication of such nanostructures possessing all these features is...

We report on the improved field emission performance of graphene foam (GF) following transient exposure to hydrogen plasma. The enhanced field emission mechanism associated with hydrogenation has been investigated using Fourier transform infrared spectroscopy, plasma spectrophotometry, Raman spectroscopy, and scanning electron microscopy. The obser...

ZnO thin film based surface and bulk acoustic wave devices are reviewed in this paper. The films were initially produced using a standard RF sputtering technique. However in order to produce lower stress, smoother films at low temperatures, a novel High Target Utilisation Sputtering (HiTUS) system has also been utilised. The ZnO acoustic devices ha...

We report novel two-dimensional (2D) shaped carbon nanotube (CNT) field emitters using triangular-shaped CNT film and its field emission properties. Using the 2D shaped CNT field emitters, we achieved excellent field emission performance with an extremely high emission current of 22 mA (equivalent to an emission current density >105 A/cm2) and exce...

We investigate the high-frequency operation of a percolation field effect transistor to monitor microwave excited single trapped charge. Readout is accomplished by measuring the effect of the polarization field associated with the oscillating charge on the AC signal generated in the channel due to charge pumping. This approach is sensitive to the r...

We report the transfer of chemical vapour deposited graphene to polymer supports by utilizing thermal and ultraviolet (UV) laminate techniques. The time-dependent evolution of the opto-electronic performance was assessed following exposure to five kinds of common dopants, FeCl 3 , SnCl 2 IrCl 3 , RhCl 3 , and AuCl 3 . In general, the doping markedl...

We report on ZnO-based thin-film transistors (TFTs) employing lanthanum aluminate gate dielectrics (Lax Al 1−xOy) grown by spray pyrolysis in ambient atmosphere at 440 °C. The structural, electronic, optical, morphological, and electrical properties of the Lax Al 1−xOy films and devices as a function of the lanthanum to aluminium atomic ratio were...

In this letter, we present a fully complementary-metal-oxide-semiconductor (CMOS) compatible microelectromechanical system thermopile infrared (IR) detector employing vertically aligned multi-walled carbon nanotubes (CNT) as an advanced nano-engineered radiation absorbing material. The detector was fabricated using a commercial silicon-on-insulator...

In this letter, we present a fully complementary-metal-oxide-semiconductor (CMOS) compatible microelectromechanical system thermopile infrared (IR) detector employing vertically aligned multi-walled carbon nanotubes (CNT) as an advanced nano-engineered radiation absorbing material. The detector was fabricated using a commercial silicon-on-insulator...

A low density CNT forest was fabricated by plasma enhanced chemical vapor deposition, and Ni nanoclusters were well distributed on the sidewall and on top of CNT forest by magnetron sputtering. The Ni deposition time plays an important role in electrochemical properties of the CNT/Ni electrodes, and the optimized deposition time is 150 to 240 s. Cy...

The film bulk acoustic resonator (FBAR) is a widely-used MEMS device which can be used as a filter, or as a gravimetric sensor for biochemical or physical sensing. Current device architectures require the use of an acoustic mirror or a freestanding membrane and are fabricated as discrete components. A new architecture is demonstrated which permits...