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1 – 10 of 57L.S. Chuah, Z. Hassan, H. Abu Hassan, C.W. Chin, S.M. Thahab and S.C. Teoh
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.
Abstract
Purpose
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.
Design/methodology/approach
Comparison was made with conventional silicon SB PDs.
Findings
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.
Research limitations/implications
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.
Originality/value
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.
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L.S. Chuah, Z. Hassan and H. Abu Hassan
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…
Abstract
Purpose
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.
Design/methodology/approach
A thin Al0.50Ga0.50N 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.
Findings
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.
Originality/value
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.
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Mehran Shahryari, Mohammad Homayoon Shakib, Mohammad Bagher Askari, Shahryar Nanekarani, Sanaz Saeidi Nejad and Sedigheh Bagheri
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…
Abstract
Purpose
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.
Design/methodology/approach
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 (Rs) and barrier height (Φb), which were determined by three analysis methods: current–voltage (I-V), Cheung function and Norde function.
Findings
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.
Originality/value
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, Φb and Rs, 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 Rs 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.
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L.S. Chuah, Z. Hassan, S.S. Tneh and S.G. Teo
The purpose of this paper is to demonstrate the n‐ZnO/p‐Si Schottky photodiodes.
Abstract
Purpose
The purpose of this paper is to demonstrate the n‐ZnO/p‐Si Schottky photodiodes.
Design/methodology/approach
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.
Findings
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.
Originality/value
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.
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Marcin Myśliwiec, Ryszard Kisiel and Marek Guziewicz
The purpose of this paper is to deal with material and technological aspects of SiC diodes assembly in ceramic packages. The usefulness of combinations of different materials and…
Abstract
Purpose
The purpose of this paper is to deal with material and technological aspects of SiC diodes assembly in ceramic packages. The usefulness of combinations of different materials and assembly techniques for the creation of inner connection system in the ceramic package, as well as the formation of outer connections able to work at temperatures up to 350°C, were evaluated.
Design/methodology/approach
The ceramic package consists of direct bonded copper (DBC) substrate with Cu pads electroplated by Ni or Ni/Au layers on which a SiC diode was assembled by sintering process using Ag microparticles. For the connections inside the ceramic package, the authors used Al/Ni and Au-Au material system based on aluminium or gold wire bonding. The authors sealed the ceramic package with glass encapsulation and achieved a full encapsulation. Outer connections were manufactured using Cu ribbon plated with Ag layer and sintered to DBC by Ag micro particle. The authors investigated the long-term stability of electrical parameters of SiC diodes assembled in ceramic package at temperature 350°C.
Findings
The authors have shown that Schottky and PiN SiC diodes assembled with different technologies and materials in ceramic package keep their I-V characteristics unchanged during ageing at 350°C for 400 h.
Originality/value
The SiC diodes assembled into ceramic package with Al/Ni or Au-Au inner electrical connection systems and outer connections system based on Ag microparticles sintering process of Cu/Ag ribbon to DBC substrate can work reliably in temperature range up to 350°C.
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Mengjie Hua, Shuo Yang, Quan Xu, Mo Chen, Huagan Wu and Bocheng Bao
The purpose of this paper is to develop two types of simple jerk circuits and to carry out their dynamical analyses using a unified mathematical model.
Abstract
Purpose
The purpose of this paper is to develop two types of simple jerk circuits and to carry out their dynamical analyses using a unified mathematical model.
Design/methodology/approach
Two types of simple jerk circuits only involve a nonlinear resistive feedback channel composited by a nonlinear device and an inverter. The nonlinear device is implemented through parallelly connecting two diode-switch-based series branches. According to the classifications of switch states and circuit types, a unified mathematical model is established for these two types of simple jerk circuits, and the origin symmetry and scale proportionality along with the origin equilibrium stability are thereby discussed. The coexisting bifurcation behaviors in the two types of simple jerk systems are revealed by bifurcation plots, and the origin symmetry and scale proportionality are effectively demonstrated by phase plots and attraction basins. Moreover, hardware experimental measurements are performed, from which the captured results well validate the numerical simulations.
Findings
Two types of simple jerk circuits are unified through parallelly connecting two diode-switch-based series branches and a unified mathematical model with six kinds of nonlinearities is established. Especially, the origin symmetry and scale proportionality for the two types of simple jerk systems are discussed quantitatively. These jerk circuits are all simple and inexpensive, easy to be physically implemented, which are helpful to explore chaos-based engineering applications.
Originality/value
Unlike previous works, the significant values are that through unifying these two types of simple jerk systems, a unified mathematical model with six kinds of nonlinearities is established, upon which symmetrically scaled coexisting behaviors are numerically disclosed and experimentally demonstrated.
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The purpose of this paper is to review recent developments in the sensing of electromagnetic radiation (EMR) with wavelengths longer than those of visible light.
Abstract
Purpose
The purpose of this paper is to review recent developments in the sensing of electromagnetic radiation (EMR) with wavelengths longer than those of visible light.
Design/methodology/approach
Following a short introduction, this paper discusses recent research into the sensing of infra‐red (IR), terahertz (THz) and microwave radiation.
Findings
It is shown that novel sensors are being developed for all of these classes of EMR. Improved IR sensors are attracting strong interest from the military, novel THz sensor developments reflect the growing uses of this radiation and research into cosmology and astronomy are driving the development of highly sensitive microwave sensors.
Originality/value
The paper provides a technical review of recent research into sensing IR, THz and microwave radiations.
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Keywords
This paper aims to provide a technical insight into a selection of recent developments and applications involving terahertz sensing technology.
Abstract
Purpose
This paper aims to provide a technical insight into a selection of recent developments and applications involving terahertz sensing technology.
Design/methodology/approach
Following an introduction, the first part of this paper considers a selection of research activities involving terahertz radiation sources and detectors. The second part seeks to illustrate how the technology is exerting a commercial impact and discusses a number of product developments and applications.
Findings
Terahertz sensing is a rapidly developing field and a strong body of research seeks to develop sources and detectors with enhanced features which often exploit novel materials, phenomena and technologies. Commercialisation is gathering pace, and a growing number of companies are producing terahertz sensing and imaging products which are finding a diversity of applications.
Originality/value
This provides details of recent research, product developments and applications involving terahertz sensing technology.
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MQ power supplies have an input voltage of 220/ 240V 48 to 440Hz. Output available is 10A, 0–16V and is adjustable from the preset value by about 10 per cent by means of a peb…
Abstract
MQ power supplies have an input voltage of 220/ 240V 48 to 440Hz. Output available is 10A, 0–16V and is adjustable from the preset value by about 10 per cent by means of a peb mounted potentiometer. It has a recovery time of less than 20µs for a 50 per cent full load change applied in less than 0.5µs.
Krzysztof Górecki and Paweł Górecki
The purpose of this paper is to propose a simple electrothermal model of GaN Schottky diodes, and its usefulness for circuit-level electrothermal simulation of laboratory-made…
Abstract
Purpose
The purpose of this paper is to propose a simple electrothermal model of GaN Schottky diodes, and its usefulness for circuit-level electrothermal simulation of laboratory-made devices is proved.
Design/methodology/approach
The compact electrothermal model of this device has the form of a subcircuit for simulation program with integrated circuit emphasis. This model takes into account influence of a change in ambient temperature in a wide range as well as influence of self-heating phenomena on dc characteristics of laboratory-made GaN Schottky diodes. The method of model parameters estimation is described.
Findings
It is shown that temperature influences fewer characteristics of GaN Schottky diodes than classical silicon diodes. The discussed model accurately describes properties of laboratory made GaN Schottky diodes. Additionally, the measured and computed characteristics of these diodes are shown and discussed.
Research limitations/implications
The presented model together with the results of measurements and computations is dedicated only to laboratory-made GaN Schottky diodes.
Originality/value
The presented investigations show that characteristics of laboratory-made GaN Schottky diodes visibly change with temperature. These changes can be correctly estimated using the compact electrothermal model proposed in this paper. The correctness of this model is proved for four structures of such diodes characterised by different values of structure area and a different assembly process.
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