Search results

To develop a silicon lateral Schottky rectifier with low forward voltage drop and low reverse leakage current while its breakdown voltage is significantly larger than that of a conventional Schottky rectifier.

A two‐dimensional device simulation has been used, to examine the effect lateral dual sidewall Schottky concept on the current‐voltage characteristics of a lateral Schottky rectifier on silicon‐on‐insulator. The Schottky contact consists of a low‐barrier metal and a high‐barrier metal.

Results show that, during forward bias, the low‐barrier Schottky (LBS) contact conducts resulting in a low forward voltage drop. During the reverse bias, the LBS contact is shielded by the depletion region of the high‐barrier Schottky contact resulting in a low reverse leakage current.

With this approach, silicon Schottky rectifiers with low power dissipation and improved breakdown voltage can be realized.

The proposed device has a large commercial potential as a low‐power high‐voltage switching device.

The purpose of this paper is to propose a new structure of GaN based metal‐semiconductor‐metal (MSM) photodiode, in which a thin unintentionally doped n‐type AlGaN layer is added on the conventional GaN on Si(111) device structure.

A thin Al_0.50Ga_0.50N cap layer of 100 nm was incorporated in GaN MSM photodiode to enhance the effective Schottky barrier height and reduce the dark current. When the incident light with photon energy higher than the band edge of GaN but lower than the bandgap of AlGaN illuminates the front face of photodiode, the light can be transparent in the top AlGaN layer and is only absorbed by the GaN layer. As a result, the photogenerated carriers in the GaN layer would be influenced by the interface states of AlGaN/GaN. It is known that the density of the interface states is normally lower than that of surface states, so the recombination of photogenerated electron‐hole pairs will be reduced. A barrier height of 0.54 eV for normal GaN MSM photodiode was increased to the effective barrier height of 0.60 eV.

The resulting MSM photodiode shows a dark current of as low as 8.0×10⁻⁴ A at 5 V bias, which is about two orders of magnitude lower than that of normal GaN (1.0×10⁻² A at 5 V bias) MSM photodiode.

The paper reports on barrier enhanced GaN Schottky MSM photodiode using a thin AlGaN cap layer. AlGaN cap layers were found to effectively suppress the leakage current of the GaN Schottky MSM photodiode, resulting in improved device characteristics. The dark current for the Schottky contact with the AlGaN cap layer was shown to be about about two orders of magnitude smaller than that of conventional GaN Schottky MSM photodiode.

The purpose of this paper is to develop a generalized model of the nonlinear conductivity of varistor ceramic suitable for solving problems of prediction and control of ceramic nonlinearity, stability of varistor properties.

The modeling of current-voltage characteristic of the intergranular barrier in metal oxide varistor ceramics is based on the development of the algorithm. It includes all the known mechanisms of electrotransfer in a wide range of voltages and currents of the current-voltage characteristics, and also takes into account the deviation of the barrier form the Schottky barrier.

The models of double Schottky barrier and double barrier of arbitrary form, as well as the algorithms for calculating the current-voltage characteristics of a single intergranular potential barrier and a separate “microvaristor” with the use of the most well-established understanding of the main mechanisms of electrical are developed. The results of current-voltage characteristics modeling correspond to the existing understanding of the nonlinear electrical conductivity varistor ceramics are based on zinc oxide. The model of double barrier of arbitrary form takes into account the deviation of the barrier form the Schottky barrier which is important in predicting the deformation of the current-voltage characteristics of the varistor products in the process of degradation.

The relation between the form of the current-voltage characteristic and the distribution profile of the donor concentration in the surface regions of the semiconductor crystallites constituting the intergranular potential barrier is established. The accumulation of donors in the space charge region leads to the increase in the current on the prebreakdown region of the current-voltage characteristic and the reduction of voltage corresponding to the breakdown region beginning of the current-voltage characteristic. The significant role of the interlayer in the formation of current-voltage characteristic of the intergranular potential barrier is shown.

The purpose of this paper is to demonstrate the existence of one suitable oxide phase concurrent with deposition for fabricating a titanium (Ti)/p-silicon (Si) Schottky diode by direct current (DC) magnetron sputtering method.

In this paper, a Ti/p-Si Schottky diode has been fabricated by depositing a Ti film on p-Si substrate by DC magnetron sputtering. Electrical properties of a Schottky junction include three main parameters: ideality factor (n), series resistance (R_s) and barrier height (Φ_b), which were determined by three analysis methods: current–voltage (I-V), Cheung function and Norde function.

As result outcomes of the calculated values by three analysis methods, average values were obtained equal to 2.475, 27.07 kÙ and 0.88 ev. With comparing direct calculation of series resistance with the achieved average value of three analysis methods, it illustrates that without X-ray diffraction (XRD) analysis consideration, it’s possible to deduce at least one oxide phase forming on the Ti layer.

This work fabricates Ti/p-Si Schottky diode by DC magnetron sputtering. By use of downward-arch region of the LnI-V curve, two functions that are known as Norde and Cheung were made with which this study applies these functions and linear region of LnI-V plot each values of n, Φ_b and R_s, except n calculated two times. With comparison of calculated values from two parts of plot, it is clear that Norde and Cheung functions are accurate and the applied method is correct. Also, with direct calculation, the value of R_s and as compared with result from analysis, this study has proved that without XRD plot, certainly simultaneity deposition at least one oxide phase was forming on Ti layer.

A computer model of silicon‐on‐sapphire MESFETs has been developed in order to help the construction and technology work of novel complementary MES digital circuit building blocks. The modelling work is based partly on physical simulation by solving the semiconductor partial differential equations, and partly on development of a large‐signal MESFET model with an arbitrary doping profile input, implemented on a nonlinear circuit analysis program. The results showed cover investigations of both DC and transient behaviour of CMES inverters.

The purpose of this paper is to describe a rapid and robust axisymmetric hybrid algorithm to create dynamic temporal and spatial charge distributions, or charge map, in the simulation of bipolar charge injection using Schottky emission and Fowler-Nordheim tunneling, field-dependent transport, recombination, and bulk and interfacial trapping/de-trapping for layered polymer films spanning the range from initial injection to near breakdown.

This hybrid algorithm uses a source distribution technique based on an axisymmetric boundary integral equation method (BIEM) to solve the Poisson equation and a fourth-order Runge-Kutta (RK4) method with an upwind scheme for time integration. Iterative stability is assured by satisfying the Courant-Friedrichs-Levy (CFL) stability criterion. Dynamic charge mapping is achieved by allowing conducting and insulating boundaries and material interfaces to be intuitively represented by equivalent free and bound charge distributions that collectively satisfy all local and far-field conditions.

Charge packets cause substantial increase of electric stress and could accelerate the breakdown of polymeric capacitors. Conditions for the creation of charge packets are identified and numerically demonstrated for a combination of impulsive step excitation, high charge injection, and discontinuous interface.

Metallized bi-axially oriented polypropylene (BOPP) dielectric thin film capacitor with self-clearing and enhanced current carrying capability offer an inexpensive and lightweight alternative for efficient power conditioning, energy storage, energy conversion, and pulsed power. The originality is the comprehensive physics and multi-dimensional modeling which span the dynamic range from initial injection to near breakdown. This model has been validated against some empirical data and may be used to identify failure mechanisms such as charge packets, gaseous voids, and electroluminescence. The value lies in the use of this model to develop mitigation strategies, including re-designs and materials matching, to avoid these failure mechanisms.

To design and optimize the traditional aluminum gallium nitride/gallium nitride high electron mobility transistor (HEMT) device in achieving improved performance and current handling capability using the Synopsys’ Sentaurus TCAD tool.

Varying material and physical considerations, specifically investigating the effects of graded barriers, spacer interlayer, material selection for the channel, as well as study of the effects in the physical dimensions of the HEMT, have been extensively carried out.

Critical figure-of-merits, specifically the DC characteristics, 2DEG concentrations and mobility of the heterostructure device, have been evaluated. Significant observations include enhancement of maximum current density by 63 per cent, whereas the electron concentration was found to propagate by 1,020 cm⁻³ in the channel.

This work aims to provide tactical optimization to traditional heterostructure field effect transistors, rendering its application as power amplifiers, Monolithic Microwave Integrated Circuit (MMICs) and Radar, which requires low noise performance and very high radio frequency design operations.

Analysis in covering the breadth and complexity of heterostructure devices has been carefully executed through extensive TCAD modeling, and the end structure obtained has been optimized to provide best performance.

The purpose of this paper is to present the characteristics of novel silicon Schottky barrier (SB) photodiodes (PDs) with aluminium nitride (AlN) (100 nm) nucleation layer.

Comparison was made with conventional silicon SB PDs.

It was found that smaller dark current could be achieved with AlN nucleation layer. It was also found that effective SB height increased from 0.65 to 0.71 eV with the insertion of the AlN layer. The dark leakage current for the Schottky PDs with the AlN layer was shown to be about two orders of magnitude smaller than that for the conventional silicon SB PDs.

It is possible that the detrimental effect of interface states situated near the metal semiconductor interface was less pronounced for the sample owing to the insertion of the AlN nucleation layer.

There is believed to be no other report on silicon SB PDs capped with an AlN layer in the literature. This paper describes the fabricated silicon SB PDs and reports on the electrical characteristics of the devices with an AlN nucleation layer grown at low temperature.

The purpose of this paper is to demonstrate the n‐ZnO/p‐Si Schottky photodiodes.

A Zn film was deposited on silicon substrate by dc sputtering deposition technology from high purity zinc (Zn) targets. Then, the Zn films were then annealed under flowing oxygen (O₂) gas environment in the furnace. ZnO nanorods morphologies have been successfully prepared through a simple method. No catalyst is required.

The structures and morphologies of the products were characterized in detail by using X‐ray diffraction, energy dispersive X‐ray, and scanning electron microscopy (SEM). According to experimental results, the current‐voltage characteristics of the device show the typical rectifying behaviour of Schottky diodes. The UV photocurrent measurement was performed using an UV lamp under a reverse bias.

The paper demonstrates that the n‐ZnO/p‐Si diodes exhibit strong rectifying conduct described by the current‐voltage (I‐V) measurement under a dark and illumination conditions.

Boundary limited transport in small compound semiconductor devices is studied within the self‐consistent Monte Carlo method. New stable microscopic models fully accounting for stochastic carrier exchange at boundaries have been developed for ohmic, tunneling, and Schottky barrier boundaries. These new models are demonstrated with applications to the one‐dimensional GaAs resistor, N+‐N‐N+ diode and the N+‐N Schottky diode.