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A concise, planar two-element super wideband MIMO antenna has been analyzed and introduced in this work for SWB bandwidth (4-40 GHz). To enhance isolation a circular ring is etched on elliptical patch of antenna and complementary split ring resonator (CSRR) on ground plane is also used. Due to closed elliptical ring resonator (CRR) on radiating patch designed antenna is circularly polarized. A hoof impedance microstrip line is used to achieve super wideband bandwidth and EBG technique is deployed near the microstrip feed line to yield high isolation(

The varying system parameters, end effector payload and environmental uncertainties are quite natural in real-world robotics applications. Therefore in order to adapt to the changing control environment and improving robustness of the controller due to an uncertain system model and dynamic uncertainties adaptive control methods are developed. This paper presents an adaptive neural backstepping control for an uncertain robot manipulator with dynamic disturbances. The dynamics of an n-link uncertain robot manipulator with dynamic disturbances is expressed as a class of 3nth order nonlinear multi-input multioutput (MIMO) system using a nonlinear disturbance observer-based model. The uncertain plant and disturbances dynamics are approximated using Radial Basis Function Network (RBFN) to derive the control law. The proposed controller for each link has a simple structure with a single unknown parameter. The update law for this unknown parameter has been obtained using Lyapunov stability. It is shown that the proposed controller is able to ensure the semi-global uniformly ultimately boundedness (UUB) of all signals of the resulting closed-loop system and the actual response eventually reaches a bounded neighbourhood of the desired response. Simulation results demonstrate the feasibility of the proposed technique. The tracking performance of the proposed controller is validated experimentally on a four degrees-of-freedom (4 DOF) Barrett Whole Arm Manipulator while performing dynamic ball hitting experiments.

In this communication, a 4 element MIMO antenna is designed for Super-Wide-Band (SWB) wireless applications. The antenna structure is comprised using four mickey-mouse shaped radiating elements. Antenna with the overall size of 60×60×1.670mm3 is implemented on the FR4 substrate using CST-Microwave lab Tool. The proposed MIMO antenna is operated with in super wide-band (SWB) frequency range (4-25GHz) with peak gain of 8.55 dB. The extended bandwidth up to such extent is accomplished by etching circular ground structures within ground plane. Isolation up to 20 dB, among the radiating elements is attained by their orthogonal placement on the substrate. Operating bandwidth, efficiency and gain of the designed antenna is compared with the prevailing literature. ECC value for the designed structure is less than 0.008 and other satisfactory performance criteria are to be considered. The presented antenna could be a good contender for several applications such as: Military mobile devices, WIMAX, C, X, Ku, and K Band.

The paper reports the terahertz generation from polycrystalline CdTe thin films using 800 nm wavelength of 35 fs pulse duration at 1 kHz repetition rate obtained from Ti: sapphire laser amplifier. These films were deposited by thermal evaporation on a glass substrate and annealed at 200 and 300°C. The structural was investigated by XRD technique. Absorbance and transmittance were recorded in the wavelength (300- 800 nm). Optical studies showed that the optical energy gap decreases with increasing annealing temperatures. The results show that the film annealed at 200°C shows the highest generation of the order of 88 nW.

Palanquins or Palkis are a part of most of the pilgrimages in India. They are primarily used where the terrain is hilly and difficult to trek. In most of the places, these are manufactured locally using wood, cane, or metal pipes. Historically, Palkis were exclusively used by the royal families and the affluent as a mode of travel. In modern times, its use is limited to ceremonies and pilgrimages. This paper analyses the traditional design of one such palki used in the pilgrimage to the Yamunotri Dham situated in the state of Uttarakhand in India. The palki used there is made of Pine Wood which is sourced locally. A 3D CAD model of the palki was made using the dimensions obtained from a porter. The model was then imported into a Finite Element Analysis software. After considering the proper contact conditions based on the actual assembly, the structural analysis was carried out on the model. The primary objective of the analysis was to find out whether the existing design was safe or not. The terrain slope was also considered in the loads applied during the analysis. It was found that the design was marginally safe up to a load of 75 kgs. However, since the properties of wood are inconsistent, a higher factor of safety is recommended. Further improvements in the design could be suggested, considering the ergonomic and sustainability factors.

The recent growth of IoT use-cases in a wide array of industrial, utility and environmental applications has necessitated the need for connectivity solutions with diverse requirements. Connectivity through BLE, Zigbee and 6LoPAN are examples of short-range IoT deployments. But to provide connectivity to a high density of devices over larger coverage areas, Low-Power Wide-Area Network (LPWAN) technologies in both licensed as well as unlicensed bands have been considered. In this paper, we consider modelling the traffic from IoT devices connected through LPWAN technologies. Due to diverse applications of IoT, it is not trivial to have a single traffic model to represent all of them, but the traffic can be broadly classified as either periodic, event-triggered, or a combination of both. We evaluate the performance of LoRaWAN, one such LPWAN technology, in the presence of a hybrid of both traffic types, where the event propagates spatially over time. In a practical deployment of sensor based IoT devices, the devices are usually densely deployed to ensure sufficient & reliable measurement. Thereby, when an event occurs, they exhibit spatial & temporal correlation in their traffic rate due to the natural phenomena of the metric they measure. We use the CMMPP model to represent such characteristic traffic from independent IoT devices triggered by an event. The characteristics of LoRa, the physical layer of LoRaWAN, is abstracted based on required signal strength and interference thresholds for different modulation parameters. Through system simulations, we demonstrate that there is a significant performance hit in LoRaWAN based networks, during the occurrence of events. In particular, using the packet delivery rate (PDR) as the metric, we found that while the system was able to handle regular updates from the devices with a PDR > 80%, event-driven traffic nearly impaired the network causing the PDR to drop below 10%.

Here, we are going to describe the design and the cost estimation of a PV analyzer based on Arduino UNO, an electronic platform. The purpose is to introduce a PV analyzer with lower manufacturing cost as compared to other's. This proposed design is the sequential assemblage of voltage sensor, current sensor, temperature sensor, variable rheostat and Arduino UNO. The analyzer will contribute in measurement and keeping the record of various output parameters like current, voltage & power. It also store the data of the parameters (temperature) affecting the output of a PV system. This designed analyzer has been tested for different probable conditions and it performed up to the mark. This sequential design can be used for any PV system providing set of the components with specific power rating. Design and cost estimation of the above mentioned analyzer can be seen here.

With the growing demand of energy across the globe, different sources and alternatives of energy has been invented or improved but PV system has been proven to be the best energy generating source. This type of dependency on solar energy is seen due to its perpetual source of energy and negligible side effect. But the efficiency of solar cell is affected due to many internal factors (due to component used in manufacturing) as well as external/environmental factors (wind, dust, humidity, location etc.). The objective of this project is to analyse the effect of dust on the performance of PV system in Manipal University, Jaipur with the use of LABVIEW based data logger. All the important parameters (open circuit voltage, short circuit current, output power etc.) related to both the panels were noted down and compared with the use of characteristic curve. It was observed that reduction in power generation of unclean panel was 9% after 55 days.

Supporting Public Protection and Disaster Relief (PPDR) services are mandatory in modern wireless access networks. The sub-1GHz band is particularly suited to provide PPDR services due to the better propagation characteristics and attendant increase in link budget. In this work, we describe a novel transmit mode under a multi-operator non-orthogonal spectrum sharing framework, which can provide robust PPDR waveforms. This Ultra-Reliable Broadcast (URB) solution is based on the Licensed Shared Simultaneous Access (LSSA) broadband wireless access system which has been designed earlier by our group to provide much higher sum-rates in each cell when compared to a single-operator network, by enabling synchronization and different levels of co-operation across multiple TDD operators simultaneously using the same air-interface technology in the same spectrum. Using 19-cell system simulation with appropriate fractional frequency reuse scenarios, we compare the post-processing SINR CDFs of the 4 operator LSSA network and a single operator network, when both of these broadcast a single network-wide PPDR message. Their performances are also compared under disaster conditions where with a probability p, any of the eNodeBs can suddenly fail. We develop and use a simple 3-D stochastic path-loss model to account for users in multi-storey buildings, where depending on the user location the mean value of the shadow loss is varied. Our simulation results in the UHF band (500MHz carrier frequency) indicate that at the 10th percentile of the CDF, under normal operating conditions, the proposed URB solution with four LSSA operators can provide more than 10dB gain in SINR, and for p=0.5, this gain increases to 14dB, when compared to the single operator system.

Present work focuses on the development of thermoelectric aluminum-doped ZnO (Al:ZnO) and NiO thin films Pulsed Laser deposition technique. XRD and Hall studies were carried out to study the structural and electrical properties of the prepared thin films. The thermoelectric studies were carried out on these films using in-house developed thermoelectric measurement set-up. The Seebeck coefficient and the electrical conductivity of the Al:ZnO and NiO thin films are found to be 31 µV/K and 20 µV/K and 902.87 S/cm and 0.096 S/cm respectively. Al:ZnO thin films yielded the comparatively higher power factor of 8.67×10−5 W/mK2 as compared to NiO thin films with power factor of 38.4×10−10 W/mK2. Results indicate the possibility of realizing thin film based self-generating integrated devices.

In the present work theoretical calculations on surface acoustic wave (SAW) propagation characteristics and acousto-optic diffraction efficiency of ZnO/IDT/AlN/Sapphire is performed. The proposed layered structure with ZnO and AlN is found to be a promising high performance SAW device, as it possess an enhanced electromechanical coupling coefficient with an appreciable SAW phase velocity and is temperature stable. Also, the proposed layered structure found to exhibits very high diffraction efficiency and very high acousto optical figure of merit coupled with nearly temperature stable characteristics indicating a bonding device for acousto optic applications.

Present work focuses on the photovoltaic properties of the multilayered structure of Bismuth ferrite (BFO) and Barium titanate (BTO) thin films prepared by Pulsed Laser Deposition (PLD) technique on platinum coated silicon substrate. The five and six layered structures of BFO/BTO showed a remarkable increase in current density (J) (from 2.23×10−7 A/cm2 to 3.18×10−4 A/cm2 and from 4.50×10−8 A/cm2 to 3.84×10−4 A/cm2) upon illumination with laser light of wavelength 405 nm at an intensity of 160 mW/cm2. The values of short circuit photocurrent and open circuit voltage (V oc ) for five layered BFO/BTO PV cell were 0.3184 mA/cm2 and −1.25 V respectively. The BFO/BTO six layer PV cell exhibits higher value of V oc = −1.52 V and J ON/OFF = 8.53 × 103 due to improved ferroelectric properties related to significant interface coupling between 6 stacking layers of BFO and BTO. The BFO/BTO PV cell highlights its possible practical application in photovoltaics and multifunctional devices.

The Ferroelectric strontium barium niobate (SBN) thin films are prepared using Pulsed Laser Deposition (PLD) technique. XRD spectra of the prepared films indicate the polycrystalline growth confirming the formation of tetragonal tungsten bronze structure. A waveguide is fabricated so as to guide the light in SBN thin film. The EO measurements for the SBN thin films have been carried out using Senarmont Compensation method in order to examine the dynamic variation of EO coefficient of the prepared films. The value of dynamic EO coefficient is found to be 198pm/V.

Iron doped ZnO thin films (ZnO:Fe) have been exploited for mediator-less biosensing application and have been realized as a potential matrix for the development of uric acid biosensor. Doping of iron in ZnO thin film tailors its redox property and electrical conductivity and a modified ZnO matrix is obtained that does not require any mediator in the solution besides bottom conducting electrode. The studies reveal that the bio-electrode based on Iron doped ZnO thin film matrix exhibits high sensitivity (298.33 μAmM−1cm−2) with good linearity over a wide range (0.05 mM to 1.0 mM) of uric acid concentration. A low value (0.16 mM) of Michaelis-Menten constant (Km) indicates high affinity of the immobilized uricase towards uric acid. The proposed ZnO:Fe thin film matrix based uric acid biosensor is found to exhibit excellent reproducibility, long shelf life (20 weeks) and high selectivity.

Nanoclusters of SnO 2 were synthesized using sol gel technique. The solution containing SnO 2 nanoclusters was spin coated on Pt inert digital electrodes/glass substrate to deposit thin film of semiconducting nanoclusters of SnO 2 (200nm). TEM images and electron diffraction pattern were studied to find out the size and polycrystalline nature of Tin oxide nanoclusters. The SnO 2 thin film was used for NO 2 gas sensing and was found to be highly sensitive to detect ultra-low concentrations (ppb range) of NO 2 at room temperature.

Thin films of semiconducting SnO 2 were deposited by using RF sputtering technique under 30% oxygen and 70% argon in the reactive (Ar+O 2 ) gas mixture using a metallic tin (Sn) target at 16 mTorr deposition pressure. The SnO 2 thin film deposited at optimized sputtering conditions was found to be highly sensitive (sensing response ∼ 1.4 × 104) to NO 2 gas (10 ppm) at comparatively low operating temperatures (∼ 100°C), but with moderate response (4.1 minutes) and recovery speeds (33.4 minutes). Further the response and recovery times of the sensor structure were improved by loading Al 2 O 3 and NiO nano clusters over SnO 2 surface using E-beam evaporation and sputtering techniques respectively. Thickness of Al 2 O 3 nano clusters was varied from 10 to 18nm to get the best sensing characteristics. The quality of SnO 2 film and reaction kinetics of NO 2 with SnO 2 surface at the Sn sites play an important role in enhancing the sensing response and response speed at low temperatures (< 200°C).

Ultra-Voilet (UV) photodetector is fabricated by rf magnetron sputtered ZnO thin films of different thickness (50 to 400 nm). ZnO film with thickness 100nm is found to exhibit enhanced UV photo response in comparison to that observed in the thicker films and is thermally treated by two different techniques, one by furnace method and another by pulsed laser irradiation. In the furnace method, the as-grown 100nm ZnO thin film is post annealed in a range of temperature from 100°C to 400°C for 1hr. The I on /I off ratio of furnace annealed ZnO film of thickness 100 nm at 300°C is found to be (7 × 103) with fast response time of 50 ms in comparison to other annelead films. In the second method, as-grown 100nm ZnO film is irradiated by pulsed Nd:YAG laser corresponding to both fundamental wavelength (1064 nm) and forth harmonics (266 nm) to modify its defects profiles. Laser (λ=266 nm) irradiated detector exhibits enhanced response (3.7 × 104) with fast response speed (30ms), showing its promising application for detection of low intensity UV photons.

Two sensor structures (SnO 2 film, and SnO 2 film-CuO nanolayer) have been prepared in the present study using both rf sputtering and pulsed laser deposition (PLD) techniques for trace level detection of H 2 S gas (20 ppm). The response characteristic of sensor structures based on bare SnO 2 thin film (90 nm) and after integrating with catalytic CuO nanolayer (10 nm) have been investigated and a comparative study has been carried out in detail. The bilayer sensor structures (SnO 2 film-CuO nanolayer) prepared by both techniques exhibits enhanced sensitivity in comparison to bare SnO 2 film sensor. PLD grown SnO 2 -CuO bilayer structure shows maximum sensor response (∼2.3×103) at a very low operating temperature of 100°C.

Calcium Bismuth Titanate (CBT) is the potential material for the high temperature piezoelectric and ferroelectric applications, and exhibits excellent property for the non-volatile FeRAM for various commercial applications. In the present study CBT thin films were prepared from sol gel technique using acetate precursor method and films were annealed over a wide temperature range (500°C–800°C). The crystallographic orientations of films were investigated using X-ray diffraction and confirmed the orthorhombic structure. Grain size of the prepared CBT film increases from 19nm to 94nm with the increases in annealing temperature from 500°C to 800°C. The transmittance of the films in the visible region decrease with the increases in annealing temperature. Raman spectroscopy study indicates the formation of single phase layered perovskite material at 700°C. Optical band gap of the CBT film annealed at 700°C was found to be minimum (3.4 eV). The dielectric constant measured at room temperature approach the bulk value for the CBT films annealed at 700°C temperature.

Resistance characteristics of thin film sensors based on uncoated SnO2, SnO2 with CuO overlayer and SnO2 with CuO dotted clusters are compared in three different backgrounds of air, oxygen and vacuum. Measurements for the three sensor configurations are carried out as a function of temperature. The novel dispersal method of CuO catalyst in the form of dotted clusters is seen to enhance the oxygen adsorption activity on surface of SnO2 thin film sensors. Conversion of molecular oxygen (O2 -) to atomic oxygen (O-) is shown to reduce the concentration of charge carriers in the conduction band of SnO2 film. Co-existence of a greater amount of adsorbed oxygen on the SnO2 film surface in conjunction with modulation of the space-charge region at the CuO-SnO2 interface are attributed to influence the resistance of the sensor structures under reducing gas.

In the present study, rf sputtered SnO2 thin films (90 nm thick) loaded with clusters of ultra-thin (8 nm) metal catalysts (Pt, Ag, Ni, Pb, Al, Pd) are investigated for LPG detection. It is noted that SnO2 film loaded with Pt catalyst clusters exhibits enhanced response (~ 750) to 200 ppm of LPG at a relatively low operating temperature (210degC) with a fast response time of 100s. Variation of thickness of Pt clusters in the nanoscale range (2 to 20 nm) is seen to significantly influence the sensor response characteristics. Enhanced performance is observed for SnO2 thin films loaded with 10 nm thick platinum clusters that exhibited a high response (~ 5 times 103) at an operating temperature of 220degC. Preliminary results indicate the potential application of prepared sensor structure of Pt clusters (10 nm)/SnO2 (90 nm)/IDE/glass substrate for efficient detection of LPG at relatively low temperature.

Ultravoilet (UV) photodetectors have been fabricated by rf magnetron sputtered ZnO films. The average grain size of ZnO films were 15-20 nm. Photo-response (Ion/Ioff) of as-grown ZnO film of thickness 100 nm was maximum (3.8 times 103) having relatively small response time ~90 ms for UV intensity of 140 muW/cm2 (lambda= 365 nm). ZnO films were irradiated by pulsed Nd:YAG laser corresponding to both fundamental wavelength (1064 nm) and forth harmonics (266 nm) to modify its defects profiles. Response was found to increase with increasing number of irradiating pulses upto 6000, and thereafter starts decreasing. Laser (lambda=266 nm) irradiated detector exhibits enhanced response (3.7 times 104) with fast response speed (30 ms), showing its promising application for detection of low intensity UV photons.

The dielectric study of HfO2 thin films deposited on the platinized silicon substrate using RF-sputtering deposition technique have been carried out in the metal-insulator-metal (MIM) configuration over a wide temperature (300 to 500 K) and frequency (100 Hz to 1 MHZ) ranges. The film were deposited at pre-optimized sputtering voltage of 0.8 kV, substrate bias of 80 volt and annealing temperature of 700degC in oxygen in order to get best results for the oxide charges and the leakage current as a MOS capacitor. The crystallographic structure of the deposited films were investigated using X-ray diffraction and the microstructure of the thin film is examined by SEM.

Highly C-axis oriented ZnO films were deposited by RF magnetron sputtering technique on unheated Si substrate with SiO2 layer deposited using thermal oxidation. We employ thermal annealing techniques with temperature range from 350degC to 800degC to investigate quality of annealed ZnO substrates. Post deposition annealing of ZnO films at atmospheric pressure in oxygen at different temperatures were found to improve film structure such as dense structure, smooth surface, and increasing resistivity. The surface morphology dramatically changes to be smooth surfaces with increase in annealing temperature. The correlation between annealing conditions and the physical structure of the films e.g. crystalline structure and microstructure was investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM). The preferred annealing condition has been found to improve ZnO film characteristics for piezoelectric applications.

SAW propagation characteristics, velocity and temperature coefficient of delay (TCD) of a 128/spl deg/ Y-X LiNbO/sub 3/ SAW device integrated with an over-layer of rf magnetron sputtered SiO/sub 2/ film have been studied. A deviation in the experimental observations with respect to the theoretical calculations on the layered structure SiO/sub 2//LiNbO/sub 3/ are identified mainly due to the difference in the material parameters of the deposited SiO/sub 2/ film. Influence of deposition conditions on the materials parameters of SiO/sub 2/ thin film have been studied, and the representative values of density, dielectric constant, elastic constants (C/sub 11/ and C/sub 44/) and their temperature coefficients have been determined, required for the design of a temperature stable SAW device.

A bi-layer structure using amorphous TeO/sub 2/ and piezoelectric ZnO thin film has been grown by reactive rf sputtering on corning glass (cg) substrate to investigate its compatibility for an acousto-optic (AO) device. Initially TeO/sub 2-x/ films were grown at different oxygen partial pressures and, structural and optical characterizations were performed to optimize the O/sub 2/ gas pressure. Effect of post-deposition annealing was studied for achieving low optical loss. Optical waveguiding was observed by prism coupling technique and the loss measurements were done. Subsequently, a high quality c-axis oriented ZnO film was grown, which is known to be suitable for SAW propagation. Finally, a TeO/sub 2/-ZnO bi-layer was grown with a clean interface and optical waveguiding was observed. Implications related to large thickness of ZnO have been discussed and a better alternate feasible TeO/sub 2/-ZnO structure is proposed.

In our earlier work enhanced H/sub 2/S detection characteristics were observed in a novel sensor structure consisting of uniformly distributed CuO islands on SnO/sub 2/ films. Ultra-thin CuO in the form of dotted islands on SnO/sub 2/ film exhibited a high sensitivity (S = 7.3 /spl times/ 10/sup 3/) at a low operating temperature (150/spl deg/C), and a fast response speed of 14 s was obtained for H/sub 2/S gas detection In the initial study the CuO islands were large in diameter (0.6 mm) quite thick (10 nm) and were widely dispersed (1.2 mm apart). In the present work a systematic study on the catalyst CuO thickness and its distribution is reported and improved response and recovery are shown with chemically derived CuO nanoparticles. The main focus is towards trace-level (20 ppm) H/sub 2/S gas detection and sensor response characteristics including sensitivity and response speed with varying distribution of CuO catalyst on SnO/sub 2/ surface. The sensor operating temperature at which a maximum response is observed is found to decrease to a lower temperature of 130/spl deg/C with surface dispersed CuO nanoparticles. The response speed of the sensors to H/sub 2/S gas becomes progressively faster when the CuO catalyst is dispersed as nanoparticles or as dotted islands onto the SnO/sub 2/ film surface. With the SnO/sub 2/-CuO-nano sensor, a high sensitivity of 2 /spl times/ 10/sup 3/ at a low operating temperature of 130/spl deg/C is obtained with a fast response speed of 16 seconds for 20 ppm of HS gas and a recovery time of 61 seconds is measured. Enhanced catalytic activity is observed due to the presence of CuO nanoparticles and their spatial distribution allows for, an effective removal of adsorbed oxygen from the uncovered SnO/sub 2/ surface. Dissociated hydrogen available from the CuO-H/sub 2/S interaction spills over and is found to be primarily responsible for the observed fast response characteristics.

Trace level detection of H/sub 2/S is of immense interest in diverse fields ranging from gas and oil exploration to dentistry. In the present work 0.12 /spl mu/m thick sputtered SnO/sub 2/ films, and a novel SnO/sub 2/-CuO bilayer structure consisting of ultra thin (/spl sim/10 nm) CuO dotted islands (0.6 mm diameter) are investigated for H/sub 2/S gas sensing. With the SnO/sub 2/-CuO-dotted sensor, a high sensitivity of 7.3/spl times/10/sup 3/ at a low operating temperature of 150/spl deg/C is obtained with a fast response time of 14 seconds for 20 ppm of H/sub 2/S gas and a recovery time of 118 seconds under flowing air have been measured. The electronic and chemical interactions of the CuO catalyst layer on SnO/sub 2/ in the presence of H/sub 2/S have been analyzed in the light of space charge regions formed due to distributed p-type CuO islands on the n-type SnO/sub 2/ thin film surface. Dissociated hydrogen available from the CuO-H/sub 2/S interaction spills over and is found to be primarily responsible for the observed fast response characteristics.

High quality crystalline c-axis oriented zinc oxide (ZnO) film has been deposited on various substrates by rf sputtering in pure argon ambient. The effect of post deposition annealing (300 K to 1073 K) on the structural and optical properties of sputtered ZnO thin film have been investigated. It is found from the XRD pattern that the intensity and the grain size increases with annealing temperature and becomes maximum for 1063 K. Also the asymmetric factor approaches to the value of one. The lattice constant and stress as a function of annealing temperature shows that up to 673 K, their is a state of stress relief and above 673 K, it goes in a state of compression. The SEM photograph also demonstrate that the grain size increases with annealing temperature, however, cracks are observed on the surface of the films annealed at 873 K. The optical band gap of the film is found to be a minimum (3.23 eV) for the films annealed at 673 K, whereas refractive index and packing density is at a maximum.

A highly c-axis oriented and insulating zinc oxide (ZnO) thin film has been deposited by rf sputtering at room temperature. We have attempted to establish the mechanism of breakdown in insulating ZnO films in a metal-insulator-metal configuration using capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics. The C-V characteristics exhibit hysteresis during the retrace. The G-V characteristic was linear for both forward and reverse bias for small bias voltages. However, for a large bias strong directional behavior depending on the polarity of the applied bias was observed. The magnitude of the maximum value of conductance and the breakdown field were found to depend on the sweep rate indicating a thermal origin for the breakdown. The non-linearity is found to depend on the substrate metallization. The Influence of bottom electrodes on the dielectric properties is also discussed.

The stability of sputtered platinum/metal bilayer metallization systems (where metal=Ti, Cr, or Ta) deposited onto SiO/sub 2//Si and TiN/Si substrates has been investigated for their resistance to oxidation in the temperature range 500 to 800/spl deg/C in O/sub 2/. RBS and SEM techniques have been used to study the interface reactions and surface morphology. Simple metallic bilayer combinations of Pt/Ti, Pt/Cr, and Pt/Ta on SiO/sub 2//Si substrates are found to be unstable. A complex Pt/TiO/sub 2//Ti/SiO/sub 2//Si structure offers good stability and can be grown without any heating using a thin TiO/sub 2/ layer and a bias sputtered Pt film. On TiN diffusion barrier layers, the Pt/TiN/Si system is unstable. Thin Ta layers in the Pt/Ta/TiN/Si structure, reduce the interdiffusion and minimize the degradation, but the surface morphology of Pt is rough.