Correlation between current-voltage and capacitance-voltagecharacteristics of Schottky barrier diodes

A correlation between the current-voltage (I-V) and the capacitance-voltage (C-V) characteristics of Schottky barrier diodes (SBDs) is revealed and claimed to be a general property of SBDs for the first time. Analytical expressions explaining the correlation based on the electric field dependence of the Schottky barrier height are derived, yielding novel approaches to evaluate Schottky barrier height lowering and to model the device behaviors     

High-performance millimetre-wave mixer diodes fabricated using a deep mesa etch approach

Schottky-barrier junction mixer diodes compatible with monolithic integration have been fabricated on semi-insulating GaAs substrates using buried VPE n+ layers and deep mesa etch processing. A 590 GHz cutoff frequency was determined using modified DeLoach analysis and fin-line chip mounting. A 5.3 dB (SSB) noise figure and a 4.8 dB conversion loss were obtained at 35 GHz for a pair of chips in a balanced microstrip mixer.     

Sub-threshold analysis and drain current modeling of polysilicon thin-film transistor using Green's function approach

An analytical analysis for a poly-crystalline silicon thin-film transistor is presented. The Green's function approach is adopted to solve the two-dimensional Poisson's equation using Neumann's boundary conditions at the silicon-silicon di-oxide interface. The developed model gives an insight of device behavior due to the effect of traps and also grain-boundary effect. The analysis of threshold voltage depicts short-channel effects and drain-induced barrier lowering. The model is extended to analyze the transfer characteristics and obtain the transconductance of the device. The results obtained show good agreement with the numerical model and with simulated results, thus proving the validity of our model.     

A 256K HCMOS ROM using a four-state cell approach

A 256K HCMOS ROM design is discussed using a geometry-variable four-state cell for high packing density. Design, area, and process margin comparisons are made to other cell approaches. The architecture of the chip is shown and device performance is summarized. The 32K/spl times/8-bit ROM has typical access times of 200 ns with 11 mA of active current at 1000-ns cycle times and typical standby currents of 300 nA. Single-layer programming is performed with the poly layer, which is in the later stages of the process cycle than field-oxide or depletion implant programmed parts. The part is produced using an n-well HCMOS process with 2-/spl mu/m poly gate lengths. The part exhibits immunity from latchup without an epi substrate layer. This is primarily due to layout procedures to insure good substrate clamping and guardbanding.     

Analysis of nonuniform nonlinear distributed feedback structures using a simple numerical approach

A simple numerical approach previously proposed for calculating the input-intensity dependence of the reflectivity and transmissivity of a nonlinear dielectric slab for incident plane electromagnetic waves is adopted for analyzing nonuniform nonlinear distributed feedback (NLDFB) structures. The method is first validated by checking with the analytic solution for the bistability characteristics of a strictly periodic, uniform NLDFB structure as well as the reported transmission characteristics of linear structures based on transfer matrix method calculation. The method is then applied to determine the transmission bistability characteristics of linearly tapered and linearly chirped NLDFB structures. The results are found to be different in some cases from those based on a generalized transfer matrix calculation in which the nonuniform structure is approximated by a set of strictly periodic, uniform segments.     

Analysis of interface states and series resistance of MIS Schottky diodes using the current-voltage (I-V) characteristics

The purpose of this paper is to analyze interface states in Al/SiO₂/p-Si (MIS) Schottky diodes and determine the effect of SiO₂ surface preparation on the interface state energy distribution. The current-voltage (I-V) characteristics of MIS Schottky diodes were measured at room temperature. From the I-V characteristics of the MIS Schottky diode, ideality factor (n) and barrier height (Φ_B) values of 1.537 and 0.763 eV, respectively, were obtained from a forward bias I-V plot. In addition, the density of interface states (N_ss) as a function of (E_ss-E_v) was extracted from the forward bias I-V measurements by taking into account both the bias dependence of the effective barrier height (Φ_e), n and R_s for the MIS Schottky diode. The diode shows non-ideal I-V behaviour with ideality factor greater than unity. In addition, the values of series resistance (R_s) were determined using Cheung’s method. The I-V characteristics confirmed that the distribution of N_ss, R_s and interfacial insulator layer are important parameters that influence the electrical characteristics of MIS Schottky diodes.     

Disocclusion: a variational approach using level lines

Object recognition, robot vision, image and film restoration may require the ability to perform disocclusion. We call disocclusion the recovery of occluded areas in a digital image by interpolation from their vicinity. It is shown in this paper how disocclusion can be performed by means of the level-lines structure, which offers a reliable, complete and contrast-invariant representation of images. Level-lines based disocclusion yields a solution that may have strong discontinuities. The proposed method is compatible with Kanizsa's (1979) amodal completion theory.     

Influence of the polysilicon doping on the electrical quality of thin oxides: a confrontation between vertical and horizontal furnaces

In this work, the influence of polysilicon doping on thin oxides (thickness equal or below 10 nm) quality and reliability (thickness equal or below 10 nm) in MOS capacitors with polysilicon gate is evaluated. By observing the polysilicon deposed in vertical and horizontal furnaces, a higher degradation in the oxide–silicon interface at high doping concentration has been found. In the case of vertical furnaces, a more evident charge trapping in the constant current stress (CCS) V(t) curves and Qbd (ERCS) degradation have also been noticed. Resistivity measurements at different concentrations show a saturation effect just in correspondence of the oxide degradation. From a morphological point of view, the poly deposited in vertical furnaces consists of grains which are larger than the ones found in horizontal furnace polysilicon and contains lower microdefectivity. Starting from these observations a model explaining the polysilicon morphology role in the oxide reliability can be proposed. According to it, the degradation of the interface is caused by the phosphorus coming from the “in situ” doped polysilicon. The hypothesis is that, at high concentrations and in presence of very large polysilicon grains, phosphorous cannot segregate at the interfaces among the polysilicon grains and, moving through the thin oxide, damages the silicon interface. This model has been confirmed by electrical, AFM and TEM analysis and all the collected data have been related to the finished devices performances (yield and reliability of CMOS flash memories, 0.25 μm technology and below).     

Noise behavior of a static induction transistor between 77 K and 300 K

The noise behavior of a Static Induction Transistor (SIT) has been studied. The SIT transistor has a relative high noise level for the low and middle frequency range and it increases with decreasing temperature. Spectral analysis for different temperatures has been carried out. Observation of the noise spectra indicates generation-recombination noise from a single energy level trap. An activation energy of 0.13 eV has been measured which might originate from a previously observed SiO complex in the bulk, this may be an important noise source in the SIT.     

Propagation characteristics of single-mode optical fibers witharbitrary complex index profiles: a direct numerical approach

We present here a rapidly converging numerical procedure for the evaluation of the propagation characteristics of a single-mode optical fiber with an arbitrary complex refractive index profile. To illustrate the procedure, we have first applied it to a fiber with a complex step index profile. As an application, we have used it to evaluate the gain in a typical 980-nm pumped erbium-doped fiber     

Two-mode chaos synchronization using a multimode external-cavity laser diode and two single-mode laser diodes

Strong optical injection and optical frequency matching have been used to effect an experimental demonstration of two-mode synchronization using a multimode external-cavity chaotic transmitter laser and two single-mode stand-alone receiver lasers. It is shown by means of synchronization diagrams and measured cross-correlation functions that the longitudinal modes of the receiver lasers have been successfully synchronized to frequency matched modes of the transmitter laser operating in the low frequency fluctuation regime.     

Fabrication and characterization of a GaN/(4H)SiC vertical pn power diode using direct and interfaced epitaxial-growth approaches

We report the fabrication and characterization of a vertical pn power diode which is realized using two separate epitaxial-growth mechanisms:(a) p-GaN over p-(4H)SiC,and(b) p-GaN over n-(4H)SiC with AlN as the interface layer.In all of the cases,n~+-doped(4H)SiC serves as the cathode substrate.Pd(200 A)/Au(10000 A) is used for the anode contact while Ni(1000 A) is used for the bottom cathode contact.The measured forward drop of the pn diode with AlN as the interface material is found to be around 5.1 V;whereas,it is 3 V for the other sample structure.The measured reverse-blocking voltage is found to be greater than 200 V.     

Bias temperature instability assessment of n- and p-channel MOS transistors using a polysilicon resistive heated scribe lane test structure

A fast wafer level device reliability stress at elevated temperatures is demonstrated. It neither needs an external heat source like a thermal chuck or an oven nor cooling. The necessary temperature for acceleration of the bias temperature stress drift mechanism is achieved by electrically resistive heating. For this reason a polycrystalline silicon (polysilicon) resistive heated test structure was designed with a MOSFET embedded between two polysilicon heater strips. A 4-terminal metal resistor above the heater allows temperature control via the temperature coefficient of the resistance. The stress algorithm performs simultaneous thermal and electrical stress. The device temperature is determined by a comparison of the temperature measured at the metal level and the pn-junction temperature determined from the forward diode characteristics. Results of an assessment of the bias temperature instability of CMOS transistors using this type of structure are discussed. They demonstrate the usefulness of the whole methodology presented.     

Design and measurements of a novel subharmonically pumpedmillimeter-wave mixer using two single planar Schottky-barrier diodes

A novel design of a subharmonically pumped millimeter-wave mixer operating at room temperature was developed and realized. The double sideband conversion loss and mixer noise temperature were measured to be 6.2 dB and 930 K, respectively, at a local oscillator frequency of 73 GHz and an IF of 1.5 GHz. These results are comparable to the best published results measured for subharmonically pumped mixers at similar frequencies. The mixer shows good performance even at IF's up to 9.5 GHz resulting in a useful RF range from 136 GHz to 156 GHz. For the first time a subharmonically pumped millimeter-wave mixer was designed without the use of any scale model measurements or other high-frequency measurements. The whole design process occurred on the basis of computer simulations. Two single low-capacitance planar air-bridge type Schottky-barrier diodes are used as the mixing elements     

Out of plane vs in plane flexural behaviour of thin polysilicon films: Mechanical characterization and application of the Weibull approach

A new MEMS for on-chip mechanical testing of 0.7 μm thick LPCVD polysilicon film has been designed, modelled and fabricated. The polysilicon film is electrostatically loaded under bending until rupture in the out of plane direction. Electrostatical numerical simulations were carried out to evaluate the force developed by the actuator and the capacitance measured by the sensing electrodes while structural numerical simulations were used to compute the stress field into the specimen and its stiffness. Elastic properties and ultimate strength of the material were determined. Comparative studies were performed to investigate the variation of the ultimate strength of the polysilicon film with different loading conditions.     

Performance and reliability of low-temperature polysilicon TFT with a novel stack gate dielectric and stack optimization using PECVD nitrous oxide plasma

This paper proposes a novel tetraethylorthosilicate (TEOS)/oxynitride stack gate dielectric for low-temperature poly-Si thin-film transistors, composed of a plasma-enhanced chemical vapor deposition (PECVD) thick TEOS oxide/ultrathin oxynitride grown by PECVD N/sub 2/O plasma. The novel stack gate dielectric exhibits a very high electrical breakdown field of 8.5 MV/cm, which is approximately 3 MV/cm higher than traditional PECVD TEOS oxide. The novel stack oxide also has better interface quality, lower bulk-trap density, and higher long-term reliability than PECVD TEOS dielectrics. These improvements are attributed to the formation of strong Si/spl equiv/N bonds of high quality ultra-thin oxynitride grown by PECVD N/sub 2/O plasma, and the reduction in the trap density at the oxynitride/poly-Si interface.     

Identify triplet-charge interaction in rubrene-based diodes using magneto-conductance: Coexistence of dissociation and scattering channels

Although it is known that triplet excitons can be quenched via triplet-charge interaction (TQI), it is still unclear how this process occurs in rubrene-based devices. We found that magneto-conductance (MC) can be used to probe the detailed mechanism of TQI in rubrene-based organic light-emitting diodes and observed the coexistence of negative and positive MC responses in the high-field region when holes and electrons were the dominant charged species at different interfaces adjoining the rubrene layer, respectively. Further analysis suggests that the negative MC response was originated from the dissociation of triplet excitons by holes, while the positive MC response was due to electron scattering by triplet excitons. The MC responses of the devices were examined under different injection currents and temperatures to confirm our hypothesis. This work gives significant insight into mechanisms of TQI in organic semiconductors, which will allow for the design of new and improved devices.     

Electron injection and interfacial trap passivation in solution-processed organic light-emitting diodes using a polymer zwitterion interlayer

Here we describe the use of a polymer zwitterion as a solution-processable material that serves as the key component of the electron injection layer (EIL) in solution processed organic light-emitting diodes (OLEDs). Poly(sulfobetaine methacrylate) (PSBMA) was employed in both regular and inverted device configurations as a work-function modifier for Al and ZnO cathodes, respectively. For both architectures, PSBMA significantly improved the OLED performance when compared to reference devices without EIL in terms of turn-on voltage and luminance. In inverted devices, PSBMA showed a passivation effect on ZnO surface trap states, producing better performing and more stable devices.     

A new approach to microstrip antennas using a mixed analysis:transient-frequency

An approach to microstrip antennas is developed that is based on a mixed transient-frequency analysis. The solution of transient integral equations by the method of moments allows one to compute the transient currents on the antenna. The Fourier transform of these transient currents used in asymptotic expressions for the far field of a Hertz dipole leads directly to harmonic parameters of radiation. The relative importance of spherical space waves and cylindrical surface waves and their behavior in terms of substrate parameters and frequency are discussed for some cases     

Nrityabodha: Towards understanding Indian classical dance using a deep learning approach

Indian classical dance has existed since over 5000 years and is widely practised and performed all over the world. However, the semantic meaning of the dance gestures and body postures as well as the intricate steps accompanied by music and recital of poems is only understood fully by the connoisseur. The common masses who watch a concert rarely appreciate or understand the ideas conveyed by the dancer. Can machine learning algorithms aid a novice to understand the semantic intricacies being expertly conveyed by the dancer? In this work, we aim to address this highly challenging problem and propose deep learning based algorithms to identify body postures and hand gestures in order to comprehend the intended meaning of the dance performance. Specifically, we propose a convolutional neural network and validate its performance on standard datasets for poses and hand gestures as well as on constrained and real-world datasets of classical dance. We use transfer learning to show that the pre-trained deep networks can reduce the time taken during training and also improve accuracy. Interestingly, we show with experiments performed using Kinect in constrained laboratory settings and data from Youtube that it is possible to identify body poses and hand gestures of the performer to understand the semantic meaning of the enacted dance piece.