Search

The materials challenge is often a major hurdle for translating good ideas in science into technologies. This is no different in the arena of quantum technologies which has seen a resurgence of interest in the last decade. This perspective provides a unique insight into the recent collaborative works by research groups in Singapore to surmount key quantum materials and processing bottlenecks that have impeded quantum technologies in the areas of sensing, computing, and communications. We highlight recent important materials related breakthroughs that have made possible novel advancements such as integrated ion traps, light frequency conversion, highly efficient cryogenic contacts to atomically thin quantum devices, and gate defined quantum dots, to name just a few. We also discuss the potential applications and conclude with our perspective on the remaining challenges to be addressed and the prospects enabled by these materials advances for future collaborations and co-developments to advance quantum technologies.

The surface-enhanced coherent anti-Stokes Raman scattering (SECARS) from a self-assembled monolayer (SAM) of benzenethiol on a silver-coated surface-enhanced Raman scattering (SERS) substrate has been measured for the 1574 cm-1 SERS mode. A value of 9.6 ± 1.7×10-14 W was determined for the resonant component of the SECARS signal using 17.8 mW of 784.9 nm pump laser power and 7.1 mW of 895.5 nm Stokes laser power; the pump and Stokes lasers were polarized parallel to each other but perpendicular to the grooves of the diffraction grating in the spectrometer. The measured value of resonant component of the SECARS signal is in agreement with the calculated value of 9.3×10-14 W using the measured value of 8.7 ± 0.5 cm-1 for the SERS linewidth Γ (full width at half-maximum) and the value of 5.7 ± 1.4×10-7 for the product of the Raman cross section σSERS and the surface concentration Ns of the benzenethiol SAM. The xxxx component of the resonant part of the third-order nonlinear optical susceptibility |3 | for the 1574 cm-1 SERS mode has been determined to be 4.3 ± 1.1×10-5 cm.g-1.s2. The SERS enhancement factor for the 1574 cm-1 mode was determined to be 3.6 ± 0.9×107 using the value of 1.8×1015 molecules/cm2 for Ns.

Raman line widths of neat benzenethiol and a self-assembled monolayer (SAM) of benzenethiol on a surface-enhanced Raman scattering (SERS) substrate have been measured using a mini spectrometer with a resolution (full width at half-maximum) of 3.3 ± 0.2 cm−1. Values of 7.3 ± 0.7, 4.6 ± 0.6, 2.4 ± 0.6, 3.2 ± 0.5, 8.8 ± 0.9, and 11.0 ± 1.1 cm−1 have been determined for the Raman line widths of the 414, 700, 1001, 1026, 1093, and 1584 cm−1 modes of neat benzenethiol. Values of 13.3 ± 0.7, 9.1 ± 0.7, 5.1 ± 0.6, 5.9 ± 0.6, 13.3 ± 0.5, and 8.7 ± 0.5 cm−1 have been determined for the SERS line widths of a benzenethiol SAM on a silver-coated SERS substrate for the corresponding frequency-shifted modes at 420, 691, 1000, 1023, 1072, and 1574 cm−1. The line widths for the SERS modes at 420, 691, 1000, 1023, and 1072 cm−1 are about a factor of two larger than those of the corresponding Raman modes. However, the line width of the SERS mode at 1574 cm−1 is slightly smaller than the corresponding Raman mode at 1584 cm−1.

a b s t r a c t The absolute Raman cross section σRS of the first-order 1332-cm − 1 optical phonons in type Ia natural diamond was measured using 785- and 1064-nm pump lasers for the excitation of Raman scattering. A small temperature-controlled blackbody was used for the signal calibration of the 785- and 1064-nm Raman systems. Measurements were made with a 0.9-mm thick (111) natural diamond sample. Values of 2.7 ± 0.6 × 10 − 29 and 0.95 ± 0.2 × 10 − 29 cm 2 per carbon atom were determined for σRS for 785- and 1064-nm excitation, respectively. The corresponding values of the Raman scattering efficiency S are 3.8 ± 0.8 × 10 − 7 and 1.3 ± 0.3 × 10 − 7 cm − 1 sr − 1 . The values of the Raman polarizability |d| for 785-, and

Electro-optical/infrared (EO/IR) sensors and photovoltaic power sources are being developed for a variety of defense and commercial applications. One of the critical technologies that will enhance both EO/IR sensor and photovoltaic module performance is the development of high quality nanostructure-based antireflection coatings. In this paper, we review our work on advanced antireflection structures that have been designed by using a genetic algorithm and fabricated by using oblique angle deposition. The antireflection coatings are designed for the wavelength range of 250 nm to 2500 nm and an incidence angle between 00 and 400. These nanostructured antireflection coatings are shown to enhance the optical transmission through transparent windows over a wide band of interest and minimize broadband reflection losses to less than one percent, a substantial improvement over conventional thin-film antireflection coating technologies.

Graphene has amazing abilities due to its unique band structure characteristics de‐ fining its enhanced electrical capabilities for a material with the highest characteris‐ tic mobility known to exist at room temperature. The high mobility of graphene occurs due to electron delocalization and weak electron–phonon interaction, mak‐ ing graphene an ideal material for electrical applications requiring high mobility and fast response times. In this review, we cover graphene’s integration into infra‐ red (IR) devices, electro-optic (EO) devices, and field effect transistors (FETs) for ra‐ dio frequency (RF) applications. The benefits of utilizing graphene for each case are discussed, along with examples showing the current state-of-the-art solutions for these applications. Graphene has many outstanding properties due to its unique bonding and subse‐ quently band gap characteristics, having electronic carriers act as “massless” DiracFermions. The material characteristics of graphene are anisotropic, having phenomenal characteristic within a single sheet and diminished material character‐ istics between sheet with increasing sheet number and grain boundaries. We will discuss the integration of graphene into many electronic device applications. Graphene has the highest mobility values measured in a material at room tempera‐ ture, allowing integration into fast response time devices such as a high electron mobility transistor (HEMT) for RF applications. Graphene has shown promise in IR detectors by utilizing graphene in thermal-based detection applications.

The components of the third-order nonlinear optical susceptibility χ(3) for the 1002-cm–1 mode of neat benzenethiol have been measured using coherent anti-Stokes Raman scattering with continuous-wave diode pump and Stokes lasers at 785.0 and 852.0 nm, respectively. Values of 2.8 ± 0.3 × 10–12, 2.0 ± 0.2 × 10–12, and 0.8 ± 0.1 × 10–12 cm·g–1·s2 were measured for the xxxx, xxyy, and xyyx components of |3χ(3)|, respectively. We have calculated these quantities using a microscopic model, reproducing the same qualitative trend. The Raman cross-section σRS for the 1002-cm–1 mode of neat benzenethiol has been determined to be 3.1 ± 0.6 × 10–29 cm2 per molecule. The polarization of the anti-Stokes Raman scattering was found to be parallel to that of the pump laser, which implies negligible depolarization. The Raman linewidth (full-width at half-maximum) Γ was determined to be 2.4 ± 0.3 cm–1 using normal Stokes Raman scattering. The measured values of σRS and Γ yield a value of 2.1 ± 0.4 × 10–12 cm·g–1·s2 for the resonant component of 3χ(3). A value of 1.9 ± 0.9 × 10–12 cm·g–1·s2 has been deduced for the nonresonant component of 3χ(3). Copyright © 2011 John Wiley & Sons, Ltd.

a b s t r a c t Coherent anti-Stokes Raman scattering (CARS) and normal anti-Stokes Raman scattering (NARS) have been measured in (001) GaP at room temperature due to the 403 cm − 1 LO phonons using a continuous wave (CW) 785.0 nm fixed-wavelength pump laser and a CW Stokes laser tunable in the 800-830 nm wavelength range. CARS measurements are normally made using pulsed lasers. The use of CW diode lasers allows a more accurate comparison between the measured and calculated values of the CARS signal. The pump and Stokes laser beams were linearly polarized perpendicular to each other, same as the pump and normal Stokes/anti-Stokes scattered light for the GaP sample used in this work. The pump and Stokes laser powers incident upon the GaP sample, located in the focal plane of a 20 mm effective focal length lens, were

Growth of vertically aligned ZnO nanowire arrays has been extensively studied on a variety of important semiconductor substrates, such as SiC and GaN. Systematic experiments were carried out to investigate the effect of growth parameters to the quality of the nanowires. In addition, the growth of nanowalls connecting individual aligned nanowires was studied and a growth mechanism was proposed. These conductive and interconnected nanowalls are indispensable for nanodevices to be fabricated on nonconductive substrates for serving as a common electrode. Finally, these nanowire arrays have been integrated as ultra violet detectors, which show good optical performance.

An extensive numerical and experimental study of deep reactive ion etched (DRIE) thin film Pb(Zr,Ti)O3 (PZT) membranes used to enhance heat transfer between an immersed integrated circuit and a dielectric fluid is presented. Modal and harmonic analysis of the vibrating PZT membranes was performed using finite element techniques for a frequency range from 0 to 5 MHz. Experimental and numerical results showed that as the size of the PZT membranes increased, their fundamental resonance frequency decreased and they exhibited an increase in the number of resonance points in a given frequency range. Square and rectangular PZT membranes showed similar resonant characteristics, while elliptic membranes displayed more resonant points than circular devices. For a specified frequency range and equivalent surface areas, square membranes had more resonant points than circular membranes. When the thin film PZT membranes are immersed in a dielectric fluid, substantial vortices and turbulences, along with distinct particle flow paths, were observed.

We present preliminary test results for the integration of a miniature crossed electric and magnetic field mass spectrometer (MS) and a small commercial gas chromatograph (GC). We targeted the experiments to identify design variables for the next generation of field-portable low-cost micro-GC–MS instruments to be developed at Lawrence Livermore National Laboratory for identification of chemical warfare agents (CWAs) and, specifically, to evaluate the potential usage of the commercial version of the compact double-focusing MS (CDFMS) as the detector component.

Novel piezoelectric cantilever beams for micro sensors and actuators based on PZT thin films have been batch fabricated by surface micromachining. Lead zirconate titanate (PZT) thin film is formed by metalorganic deposition (MOD) on Pt/Ti/SiO2/Si (1 0 0) substrates and Pt/Ti/LTO/Si3N4 cantilever beams and then annealed at 700 °C in air. The PZT thin film is 0.5 μm thick and has dielectric permittivity of 1698, remanent polarization of 13.66 μC/cm2, and coercive field of 44.5 kV/cm. The influence of deposition temperatures on PZT thin film stress has been investigated. When continuously controlling the deposition temperatures, the stress of the thin film is reduced from 0.313 × 108 to 0.269 × 108 N/m, that is 16.4% decrease. With the total 120 designed devices on 4-inch wafers, the number of functional devices is increased from 82 to 97, that is 12.47%.

A linear stepper motor has been constructed with submicrometer step size and centimeter travel range. Silicon wafers with conventional dielectrics provide a basic electrostatic clamping mechanism, while a piezoelectric material serves as an electrical-to-mechanical power transducer. Movement is generated by using the inertial properties of an attached mass coupled with fast and slow expansions and contractions of the piezoelectric material. The fast transitions use the inertia of the mass to move the clamp, while the slow transitions move the mass while keeping the clamp fixed. Five prototype hand-held stepper motors have been successfully built and tested. The components of the motor fit within a pen-sized cylindrical stainless steel shell (15 cm /spl times/ 1.2 cm) and deliver a displacement of 38 mm. For the given operating conditions, the tested handpieces had 1.2 mm/s advancement speeds against a 3 N load. The electrostatic clamp generates an attraction force of about 2 N using a clamp with an area of 3.75 cm/sup 2/ and 150 V across the faces. Maximum step sizes for the piezoelectric transducer (PZT) used here are slightly less than 10 /spl mu/m, and steps less than 100 nm can be obtained with sufficiently low PZT voltages. Motor speed can be controlled by adjusting the operating frequency.

Optical sensing technology is critical for optical communication, defense and security applications. Advances in optoelectronics materials in the UV, Visible and Infrared, using nanostructures, and use of novel materials such as CNT and Graphene have opened doors for new approaches to apply device design methodology that are expected to offer enhanced performance and low cost optical sensors in a wide range of applications. This paper is intended to review recent advancements and present different device architectures and analysis. The chapter will briefly introduce the basics of UV and Infrared detection physics and various wave bands of interest and their characteristics [1, 2] We will cover the UV band (200-400 nm) and address some of the recent advances in nanostructures growth and characterization using ZnO/MgZnO based technologies and their applications. Recent advancements in design and development of CNT and Graphene based detection technologies have shown promise for optical sensor applications. We will present theoretical and experimental results on these device and their potential applications in various bands of interest.

A unique design of an implantable micropump for medical drug delivery systems was proposed. The peristaltic pumping principle was selected. Three pump chambers are individually actuated by each bulk PZT (lead zirconate titanate) disk in a peristaltic motion. It is this peristaltic motion that propels the fluid. The design of the micropump includes inlet, three pump chambers, three silicon membranes, three normally closed active valves, three bulk PZT actuators, three actuation reservoirs, flow microchannels, and outlet. To prohibit flow when no power is applied, the micropump was designed to be normally closed. The pump features an integral valve/membrane design such that the pump chambers not only pump the liquid, but also function as the inlet and outlet valves. To determine the dimensions of the proposed micropump, analytical modeling of the micropump chamber was conducted. The design tradeoffs between maximizing the pumped volume and reducing the overall size of the proposed micropump were analyzed. An electromechanical coupled field simulation using the FEA method was employed. Based upon the simulation results, 6 and 12 mm diameter silicon membranes with different thickness of 40 and 80 μm were fabricated using microelectromechanical systems (MEMS) technology. The deflection of these silicon membranes was tested. The PZT actuator was manually glued onto the micropump chamber. The testing data agreed well with the FEA simulation of the deflection. The conductive adhesive layer dramatically reduces the deflection. A 12 mm in diameter and 40 μm thick silicon membrane in each pump chamber is needed to meet the micropump design requirements. The fabrication and experiments of these silicon membranes reported in this paper determine the dimensions and fabrication processes for the complete micropump. A 70 mm ×35 mm ×1.0 mm micropump will be fabricated using MEMS fabrication technology. The complete micropump will be characterized to verify our design.

The fabrication and structural characterization of a surface micromachined, resonant frequency, Pb(Zr, Ti)O3 (PZT) microcantilever will be presented. The PZT microcantilever was fabricated using surface micromachining techniques, and used a low-stress silicon nitride thin film as the base material for the microcantilever onto which a PZT thin film was incorporated. The PZT thin film is used as both the microsensor and the microactuator. A unique fabrication procedure was developed in order to eliminate the step of encapsulating the PZT during the removal of the spacer layer. The encapsulation step was avoided because of the difficulty in finding a suitable material, which would protect the PZT during the removal of the spacer layer yet not affect its material properties. This predicament was resolved by removing the spacer layer prior to the deposition of the PZT. The microcantilevers were characterized extensively using an atomic force microscope in an unusual manner. The atomic force microscope was modified in such a fashion that the deflection at the tip of the microcantilever could be measured as the frequency of an electrical signal applied to the PZT thin film was varied. In addition, an impedance analyzer was used to characterize the microcantilevers. Simple thin-film, laminated plate theory was used to obtain a closed-form solution for the modal response of the microcantilever, while ANSYS was used to obtain modal and harmonic simulation results. It will be shown that the experimental, numerical, and theoretical modal results are within ±10% of one another. The experimental and numerical harmonic results differ by an order of magnitude; however, the numerical model is currently being modified to more accurately represent the PZT microcantilever. From the information gathered during the structural characterization of the PZT microcantilever, it will be shown that certain higher-order resonant frequency modes have very large mechanical responses. These higher-order resonant frequency modes give designers another parameter to adjust when trying to optimize the design of their resonant frequency device.

Two piezoresistive (n-polysilicon) strain sensors on a thin Si3N4/SiO2 membrane with improved sensitivity were successfully fabricated by using MEMS technology. The primary difference between the two designs was the number of strips of the polysilicon patterns. For each design, a doped n-polysilicon sensing element was patterned over a thin 3 μm Si3N4/SiO2 membrane. A 1000×1000 μm2 window in the silicon wafer was etched to free the thin membrane from the silicon wafer. The intent of this design was to fabricate a flexible MEMS strain sensor similar in function to a commercial metal foil strain gage. A finite element model of this geometry indicates that strains in the membrane will be higher than strains in the surrounding silicon. The values of nominal resistance of the single strip sensor and the multi-strip sensor were 4.6 and 8.6 kΩ, respectively. To evaluate thermal stability and sensing characteristics, the temperature coefficient of resistance [TCR=(ΔR/R0)/ΔT] and the gage factor [GF=(ΔR/R0)/e] for each design were evaluated. The sensors were heated on a hot plate to measure the TCR. The sensors were embedded in a vinyl ester epoxy plate to determine the sensor sensitivity. The TCR was 7.5×10−4 and 9.5×10−4/°C for the single strip and the multi-strip pattern sensors. The gage factor was as high as 15 (bending) and 13 (tension) for the single strip sensor, and 4 (bending) and 21 (tension) for the multi-strip sensor. The sensitivity of these MEMS sensors is much higher than the sensitivity of commercial metal foil strain gages and strain gage alloys.

Microelectromechanical strain sensors were fabricated and embedded in laminated composites. These small scale sensors were designed to function as part of a wireless sensing network. The sensing element, signal conditioning, and telemetry circuitry have been developed to be fabricated on a single silicon wafer. In this paper, the sensor design and function are described. The most critical feature for sensor design was the strain transfer between the sensor and composite matrix. Finite element models were developed to investigate various designs prior to manufacture. Two types of sensors were produced, sensors which were integral to the wafer, and sensors which were thin silicon nitrate beams attached to the wafer only at the beam root. An overview of experimental data from an extensive series of tests will be presented.

Electrically conductive LaNiO3 (LNO) and ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thin films were deposited on single crystal (100)SrTiO3 (STO), (100)LaAlO3 (LAO), and Pt/Ti/SiO2/Si(100) substrates using solution deposition routes. X-ray diffraction and scanning electron microscopy were used to investigate the crystallinity and microstructure of the films. The surface bonding states of the PZT and LNO films were determined by X-ray photoelectron spectroscopy (XPS). The average room-temperature dielectric constant of the PZT films, measured at 1 kHz, was in the range 905–1002 and the dissipation factor was below 0.03 for all films. The remnant polarization and coercive electric field of the PZT/LNO films deposited on (100)STO, (100)LAO, and Pt/Ti/SiO2/Si substrates were 30, 32 and 19 μC/cm2, and 84, 87 and 57 kV/cm, at applied electric field of 450 kV/cm, respectively.

Micromechanical in-plane strain sensors were fabricated and embedded in fiber-reinforced laminated composite plates. Three different strain sensor designs were evaluated: a piezoresistive filament fabricated directly on the wafer; a rectangular cantilever beam; and a curved cantilever beam. The cantilever beam designs were off surface structures, attached to the wafer at the root of the beam. The composite plate with embedded sensor was loaded in uniaxial tension and bending. Sensor designs were compared for repeatability, sensitivity and reliability. The effects of wafer geometry and composite plate stiffness were also studied. Typical sensor sensitivity to a uniaxial tensile strain of 0.001 (1000 /spl mu//spl epsi/) ranged from 1.2 to 1.5% of the nominal resistance (dR/R). All sensors responded repeatably to uniaxial tension loading. However, for compressive bending loads imposed on a 2-3-mm-thick composite plate, sensor response varied significantly for all sensor designs. This additional sensitivity can be attributed to local buckling and subsequent out of plane motion in compressive loading. The curved cantilever design, constructed with a hoop geometry, showed the least variation in response to compressive bending loads. All devices survived and yielded repeatable responses to uniaxial tension loads applied over 10 000 cycles.

Lead scandium niobate titanate (Pb[Sc 1/2 Nb 1/2 ) 0.57 Ti 0.43 ]O 3 ) thin films with 0.5 mol% Nb doping were prepared by a sol–gel method. Films annealed at temperatures greater than 600°C crystallized into a single phase perovskite structure. The films were transparent and crack-free with uniform thickness and an average grain size of 1.1 μm. The dielectric constant and dissipation factor measured at 1 kHz for a film annealed at 700°C were 1370 and 0.022, respectively. Ferroelectricity was confirmed by the presence of hysteresis loops, with a remanent polarization of 20 μC/cm 2 and coercive field of 35 kV/cm. The piezoelectric coefficient ( d 33 ) of a poled film was 98 pm/V. Dielectric, ferroelectric, and piezoelectric properties of the films were enhanced through annealing and poling after deposition of the top gold electrode.

Uniformly aligned ZnO nanobelt (NB) arrays have been grown on a (0001) GaN substrate without foreign catalyst such as Au. The NBs mainly grew along [0113] at beginning when the temperature was relatively low, then switched to [0110] at high temperature, and finally switched to [0113] when the temperature was lowed. The alignment of the NBs was due to not only the epitaxial orientation relationship with the substrate but more importantly the presence of metallic Zn nanoparticles at the tip of the ZnO NBs, which were produced by reduction of ZnO source material. The Zn nanoparticle has a fixed orientation relationship with the ZnO NB, indicating that the growth follows the self-catalyzed vapor−liquid−solid process.

▪ Abstract Piezoelectric materials have been integrated with silicon microelectromechanical systems (MEMS) in both microsensor and microactuator applications. Thin-film materials selection and processing routes are reviewed. Some recent and emerging applications of piezoelectric MEMS are presented including acoustic emission microsensors, vibration monitors, molecular recognition biosensors, precision positioners, micropumps, and linear stepper motors.

This paper discusses the fabrication process and challenges for fabrication of piezoelectric cantilever beam microaccelerometers by using surface micromachining techniques. PZT thin films were used as the piezoelectric material to detect the acceleration of the cantilever beam. In this paper, we discuss in detail the process challenges encountered in piezoelectric microaccelerometers. These major challenges include PZT thin film deposition and encapsulation during final micromachining membrane release.

A ferroelectric test chip has been fabricated consisting of 1) piezoelectric (PZT) microsensors (accelerometers), 2) low-voltage, 3-μm, n-well CMOS signal conditioning electronics, 3) high-voltage (HVMOS) drive electronics, and 4) PZT microactuator diaphragms and cantilevers. This test chip has been developed to address processing problems encountered in the fabrication of integrated ferroelectric microelectromechanical systems (FMEMS). A description fabrication, IC-compatible process integration, electrical performance of diagnostic MEMS circuits and devices is presented.

Surface-micromachining techniques have been used in the fabrication of a 64/spl times/64 element PbTiO/sub 3/ pyroelectric infrared imager. Polysilicon microbridges of 1.2 /spl mu/m-thickness have been formed 0.8 /spl mu/m above the surface of a silicon wafer. Each of the 4096 polysilicon microbridges measures 50/spl times/50 /spl mu/m/sup 2/ and forms a low thermal mass support for a 30/spl times/30 /spl mu/m/sup 2/ PbTiO/sub 3/ pyroelectric capacitor with a thickness of 0.36 /spl mu/m. The air-bridge formed reduces the thermal conduction path between the detector element and substrate. An NMOS preamplifier cell is located directly beneath each microbridge element. The measured blackbody voltage responsivity at 30 Hz is 1.2/spl times/10/sup 4/ V/W. The corresponding measured normalized detectivity (unamplified) D* is 2/spl times/10/sup 8/ cm-Hz/sup 1/2/W at 30 Hz. The test chip fabricated measures 1/spl times/1 cm/sup 2/ and contains more than ten thousand transistors and 4096 micromechanical structures with integrated ferroelectric microsensors. The technique of stacking of microsensors and integrated circuits represents a new approach for achieving high-density and high-performance integrated pyroelectric microsensors through minimization of circuit to sensor interconnection with extremely small thermal crosstalk. >

Lanthanum doped Pb(Zr, Ti)O3 thin films have been fabricated by the solgel deposition technique. The small-signal dielectric constant ϵ has been investigated in the temperature range of 25°C to 550°C. The maximum value in the dielectric constant occurs at certain temperature for each particular composition. The apparent critical temperature is close to the Curie temperature reported in literature for the bulk material with similar composition. Lanthanum modified PbTiO3 and PbZrTiO3 have shown lower and broaden peaks. Ferroelectric hysteresis loops have been observed. The shape of the loop, the amplitude of the remnant polarization, and the coercive field significantly changed when the films were heated across the critical temperature that appeared in the dielectric constant curve. The critical temperature is assumed to be associated to the phase boundaries between the paraelectric-cubic and the ferroelectric tetragonal phases. A diffuse phase transition region were observed in lanthanum doped films.

In recent years a substantial amount of research has focused on the mechanical and electro-optical properties of ZnO nanowires (NWs). Initially, a significant portion of the work involved developing either single NWs or NW arrays for photo detection at ultraviolet (UV) wavelengths, and the innovation and performance of such devices have subsequently and progressively advanced. In addition, several new areas of ZnO NW research have since appeared, with energy harvesting at the forefront. The piezoelectric potential of nanowires has been a source of considerable interest, and novel concepts have been reported, including devices that convert thermal energy and sound waves into electrical power. In this paper we will address recent work (mostly published within the past couple years) on both ZnO NW based UV photodetectors and energy harvesting, seeking in the process to identify notable and innovative features that are advancing ZnO NW technology and nanodevice performance.

Next Generation EO/IR focal plane arrays using nanostructure materials are being developed for a variety of Defense Applications including Unattended Ground Sensor Applications. Several different nanomaterials are being evaluated for these applications. These include ZnO nanowires that have demonstrated large signal to noise ratio as a wide band gap nanostructure material in the UV band. Similarly, the work is under way using Carbon Nanotubes (CNT) for a high speed detector and focal plane array as bolometer for IR bands of interest, which can be implemented for the unattended ground sensor applications. In this paper, we will discuss the sensor design and model predicting performance of an EO/IR focal plane array that can cover the UV to IR bands of interest. The model can provide a robust means for comparing performance of the EO/IR FPA's and Sensors that can operate in the UV, Visible-NIR (0.4-1.8μ), SWIR (2.0-2.5μ), MWIR (3-5μ), and LWIR bands (8-14μ). This model can be used as a tool for predicting performance of nanostructure arrays under development. We will also discuss our results on growth and characterization of ZnO nanowires and CNT's for the next generation sensor applications. Several approaches for compact energy harvesting using nanostructures will be discussed.

Next Generation EO/IR focal plane arrays using nanostructure materials are being developed for a variety of Defense and Homeland Security Sensor Applications. Several different nanomaterials are being evaluated for these applications. These include ZnO nanowires, GaN Nanowires and II-VI nanowires, which have demonstrated large signal to noise ratio as a wide band gap nanostructure material in the UV band. Similarly, the work is under way using Carbon Nanotubes (CNT) for a high speed detector and focal plane array as two-dimensional array as bolometer for IR bands of interest, which can be implemented for the sensors for homeland security applications. In this paper, we will discuss the sensor design and model predicting performance of an EO/IR focal plane array and Sensor that can cover the UV to IR bands of interest. The model can provide a robust means for comparing performance of the EO/IR FPA's and Sensors that can operate in the UV, Visible-NIR (0.4- 1.8μ), SWIR (2.0-2.5μ), MWIR (3-5μ), and LWIR bands (8-14μ). This model can be used as a tool for predicting performance of nanostructure arrays under development. We will also discuss our results on growth and characterization of ZnO nanowires and CNT's for the next generation sensor applications. We also present several approaches for integrated energy harvesting using nanostructure based solar cells and Nanogenerators that can be used to supplement the energy required for nanostructure based sensors.

Ultra-high, broadband transmittance through coated glass windows is demonstrated over a wide range of incident angles. Near perfect 100% transmittance through a glass substrate has been achieved over select spectral bands, and the average transmittance increased to over 97% for photons incident between 0° and 75° with wavelengths between 400 nm and 1600 nm. The measured improvements in transmittance result from coating the windows with a new class of materials consisting of porous SiO2 nanorods.

EO/IR Nanosensors are being developed for a variety of Defense and Commercial Systems Applications. These include UV, Visible, NIR, MWIR and LWIR Nanotechnology based Sensors. The conventional SWIR Sensors use InGaAs based IR Focal Plane Array (FPA) that operate in 1.0-1.8 micron region. Similarly, MWIR Sensors use InSb or HgCdTe based FPA that is sensitive in 3-5 micron region. More recently, there is effort underway to evaluate low cost SiGe visible and near infrared band that covers from 0.4 to 1.6 micron. One of the critical technologies that will enhance the EO/IR sensor performance is the development of high quality nanostructure based antireflection coating. Prof. Fred Schubert and his group have used the TiO2 and SiO2 graded-index nanowires / nanorods deposited by obliqueangle deposition, and, for the first time, demonstrated their potential for antireflection coatings by virtually eliminating Fresnel reflection from an AlN-air interface over the UV band. This was achieved by controlling the refractive index of the TiO2 and SiO2 nanorod layers, down to a minimum value of n = 1.05, the lowest value so far reported In this paper, we will discuss our modeling approach and experimental results for using oblique angle nanowires growth technique for extending the application for UV, Visible and NIR sensors and their utility for longer wavelength application. The AR coating is designed by using a genetic algorithm and fabricated by using oblique angle deposition. The AR coating is designed for the wavelength range of 400 nm to 2500 nm and 0° to 40° angle of incidence. The measured average optical transmittance of an uncoated glass substrate between 1000 nm and 2000 nm is improved from 92.6% to 99.3% at normal incidence by using a two-layer nanostructured AR coating deposited on both surfaces of the glass substrate.

Next Generation EO/IR focal plane arrays using nanostructure materials are being developed for a variety of Defense Applications including Unattended Ground Sensor Applications. These include ZnO nanowires that have demonstrated large signal to noise ratio as a wide band gap nanostructure material in the UV band. Similarly, the work is under way using Carbon Nanotubes (CNT) for a high speed detector and focal plane array as bolometer for IR bands of interest, which can be implemented for the unattended ground sensor applications. In this paper, we will discuss the sensor design and model predicting performance of an EO/IR focal plane array that can cover the UV to IR bands of interest. The model can provide a robust means for comparing performance of the EO/IR FPA's and Sensors that can operate in the UV, Visible-NIR (0.4-1.8μ), SWIR (2.0-2.5μ), MWIR (3-5μ), and LWIR bands (8-14μ). This model can be used as a tool for predicting performance of nanostructure arrays under development. We will also discuss our results on growth and characterization of ZnO nanowires and CNT's for the next generation sensor applications.

In this Paper we present growth and characterization results of highly oriented ZnO nanowires grown on wide bandgap GaN substrates. Experimental results on the ZnO nanowires grown on p-GaN are presented with growth morphology and dimensionality control. We also present experimental results on these nanowire arrays such as I-V measurements and UV sensitivity measurements. The ZnO nanowires can be used for a variety of nanoscale optical and electronics applications.

Pyroelectric lead titanate (PbTiO3) thin films deposited by sol—gel processing have been characterized for possible use in microsensor applications. Based on a comparison of relevant properties with other IC-compatible pyroelectric materials, PbTiO3 possesses a very high pyroelectric coefficient over a wide operating temperature range. The measured pyroelectric coefficient at 297 K for PbTiO3, films with thicknesses ranging from 0.2 to 0.6 μm is in the range 75 to 96 nC/cm2K. This paper presents the first use of PbTiO, as a pyroelectric material integrated into a micromachined membrane structure. This composite structure offers a key advantage of implementing a low thermal mass for high-sensitivity pyroelectric detection. The measured blackbody voltage responsivity for a pyroelectric element with an active area of 4 × 10−5 cm2 at 297 K and a chopping frequency of 100 Hz is 2.2 × 104 V/W. The normalized detectivity D* at 100 Hz is 1.0 × 109 cm Hz 1 2 /W. The response time measured by the pulsed laser-beam method for a device area ranging from 2 × 10−6 to 7 × 10−4 cm2 is in the range 2–20 μs.

RF MEMS technologies are rapidly being integrated into RF subsystems for a variety of applications of interest to the Department of Defense. New technologies such as RF high-Q MEMS resonators and micromechanical arrays are being developed that will enable filters and other high-performance passive components for fully integrated microsystems. Large off-chip filters will be replaced by arrays of MEMS resonators to enable monolithic chip-scale spectrum analyzers and channelizers. RF MEMS switches are being continually improved for low-loss, high-isolation switching with enhanced reliability critical to the performance of both military and commercial systems.

EO/IR nanosensors are being developed for a variety of Defense and Commercial Systems Applications. These include UV, Visible, NIR, MWIR and LWIR nanotechnology based Sensors. The conventional SWIR Sensors use InGaAs based IR Focal Plane Array (FPA) that operate in 1.0-1.8 micron region. Similarly, MWIR Sensors use InSb or HgCdTe based FPA that is sensitive in 3-5 micron region. More recently, there is effort underway to evaluate low cost SiGe visible and near infrared band that covers performance up to 1.6 micron. The use of nanowires for developing high quality antireflection coatings that allows minimizing the reflection loss is discussed. We have explored the possibility of using nanostructures grown by oblique angle deposition technique. A graded-index coating with different index profiles has been investigated for broadband antireflection properties, particularly with air as the ambient medium. In this paper, we present, modeling and experimental results for nanostructure AR coatings for UV, Visible and calculations for NIR sensors and also their utility for longer wavelength application.

UV response of ZnO nanowire nanosensor has been studied under ambient condition. By utilizing Schottky contact instead of Ohmic contact in device fabrication, the UV sensitivity of the nanosensor has been improved by four orders of magnitude, and the reset time has been drastically reduced from 417 to 0.8 s. By further surface functionalization with function polymers, the reset time has been reduced to 20 ms even without correcting the electronic response of the measurement system. These results demonstrate an effective approach for building high response and fast reset UV detectors. © 2009 American Institute of Physics. DOI: 10.1063/1.3133358 Ultraviolet UV photon detectors have a wide range of applications from environmental monitoring, missile launching detection, space research, high temperature flame detection to optical communications. 1 For these applications, fast response time, fast reset time, high selectivity, high responsivity, and good signal-to-noise ratio are commonly desired characteristics. 2 For UV photon detector based on polycrystalline ZnO thin film, a slow response time ranging from a few minutes to several hours is commonly observed. 3,4 Due

EO/IR Sensors have been developed for a variety of Military Systems Applications. These include UV, Visible, SWIR, MWIR and LWIR Sensors. The conventional SWIR Sensors using InGaAs Focal Plane Array (FPA) can operate in 0.4 - 1.8 micron region. Similarly, MWIR Sensors use InSb and HgCdTe based FPA's that are sensitive in 3-5 and 8-14 micron region. DOD investments in the last 10 years have provided the necessary building blocks for the IR Sensors that are being deployed in the field. In this paper, we discuss recent developments and work under way to develop Next Generation nanostructure based EO/IR detectors that can potentially cover UV, Visible and IR regions of interest. The critical technologies being developed include ZnO nanostructures with wide band gap for UV detection and Carbon Nanostructures that have shown the feasibility for IR detection. Experimental results on ZnO based nanostructures demonstrate enhanced UV sensitivity and path forward for larger arrays. Similarly, recent works on carbon nanostructures have shown the feasibility of IR detection. Combining the two technologies in a sensor can provide multispectral capability.

Next Generation EO/IR Sensors using Nanostructures are being developed for a variety of Defense Applications. In addition, large area IRFPA's are being developed on low cost substrates. In this paper, we will discuss the capabilities of a EO/IR Sensor Model to provide a robust means for comparing performance of infrared FPA's and Sensors that can operate in the visible and infrared spectral bands that coincide with the atmospheric windows - UV, Visible-NIR (0.4-1.8μ), SWIR (2.0-2.5μ), MWIR (3-5μ), and LWIR (8-14μ). The model will be able to predict sensor performance and also functions as an assessment tool for single-color and for multi-color imaging. The detector model can also characterize ZnO, Si, SiGe, InGaAs, InSb, HgCdTe and Nanostructure based Sensors. The model can predict performance by also placing the specific FPA into an optical system, evaluates system performance (NEI, NETD, MRTD, and SNR). This model has been used as a tool for predicting performance of state-of-the-art detector arrays and nanostructure arrays under development. Results of the analysis can be presented for various targets for each of the focal plane technologies for a variety of missions.

Three types of microactuator for linear displacement are presented which use piezoelectric thin films for the electrical-to-mechanical energy conversion process. One actuator uses a folded-path or meander-line geometry to produce horizontal tethered linear displacements. The second geometry uses a number of unimorph bars arranged in a planar format and mechanically connected in series to produce a tethered displacement perpendicular to the plane containing the unimorphs. The third actuator uses an inertial recoil mechanism in conjunction with an electrostatic clamp to produce incremental stepping motion. Sufficient repetition of the stepping sequence produces virtually unlimited travel range, being limited by practical considerations such as electrical connections. Electromechanical models for all three actuators are developed and are used to quantitatively estimate the performance of microactuators designed to a particular set of dimensions. Fabrication procedures for the microactuators have been developed and the status of the fabrication efforts is presented.

The pyroelectric coefficients and pyroelectric response in lead zirconate titanate (Pb(ZrxTi1−x)O3), lead titanate (PbTiO3), and zinc oxide (ZnO) thin films (0.1–2.0‐μm thick) have been studied for possible integrated thermosensor applications. Pyroelectric properties of these films deposited on thick (500‐μm) silicon substrates and thin (1.0‐μm) polysilicon membranes have been investigated. The measured pyroelectric coefficients for these materials are 70, 95, and 1.0 nC/cm2 K for Pb(Zr0.54Ti0.46)O3, PbTiO3, and ZnO, respectively. Coupling effects between the pyroelectric film and substrate were studied. It was observed that the primary pyroelectric effect dominates the pyroelectric response in Pb(Zr0.54Ti0.46)O3 and PbTiO3 thin films while the secondary effect is dominant in ZnO thin films.

The compact linear-motion piezoelectric actuator developed has relatively large displacement capabilities. It is composed of a number of parallel bars of lead zirconium titanate (PZT) connected together in a meander-line configuration so that they are mechanically in series and electrically in parallel. The polarity of the adjacent bars is arranged so that if a given bar expands under the applied voltage, the adjacent bars contract. An electromechanical model of the actuator predicted and measurements verified that stiffeners added to the basic meander line geometry significantly increased the force output without affecting the displacement versus applied voltage relationship. >