Muammar Mohamad Isa

Characterization of self-switching diodes as microwave rectifiers using ATLAS simulator

A planar nanodevice, known as the self-switching diode (SSD), has a nonlinear current-voltage (I-V) characteristic which can be exploited as a high-speed rectifier in a wide range of applications. This diode-like I-V behaviour is achieved due to the structure of the device which consists of an asymmetric nanochannel. In this work, the rectification properties of silicon-based SSDs with different geometry of the nanochannel were reported. The characterization have been performed by means of ATLAS device simulator. The results obtained can be used to facilitate in improving the rectifying performance of the device.

An overview of self-switching diode rectifiers using green materials

A unipolar two-terminal nanodevice, known as the self-switching diode (SSD), has recently been demonstrated as a room-temperature rectifier at microwave and terahertz frequencies due to its nonlinear current-voltage characteristic. The planar architecture of SSD not only makes the fabrication process of the device faster, simpler and at a lower cost when compared with other rectifying diodes, but also allows the use of various materials to realize and fabricate SSDs. This includes the utilization of ‘green’ materials such as organic and graphene thin films for environmental sustainability. This paper reviews the properties of current ‘green’ SSD rectifiers with respect to their operating frequencies and rectifying performances, including responsivity and noise-equivalent power of the devices, along with the applications.A unipolar two-terminal nanodevice, known as the self-switching diode (SSD), has recently been demonstrated as a room-temperature rectifier at microwave and terahertz frequencies due to its nonlinear current-voltage characteristic. The planar architecture of SSD not only makes the fabrication process of the device faster, simpler and at a lower cost when compared with other rectifying diodes, but also allows the use of various materials to realize and fabricate SSDs. This includes the utilization of ‘green’ materials such as organic and graphene thin films for environmental sustainability. This paper reviews the properties of current ‘green’ SSD rectifiers with respect to their operating frequencies and rectifying performances, including responsivity and noise-equivalent power of the devices, along with the applications.

Permittivity and temperature effects to rectification performance of self-switching device using two-dimensional simulation

Characterization on an InGaAs-based self-switching diode (SSD) aimed for rectification application at high frequencies is reported. Simulation on the current-voltage (I-V) characteristic of L-shaped 70 nm channel SSD has been conducted using ATLAS two-dimensional (2D) simulator for different insulating channel materials with relative permittivity ranging from 1.0 to 9.3 under temperature range of 300 K-600 K. A similar I-V curve to diode behavior has been observed. Furthermore, the curvature co-efficient of the SSD has been evaluated by extrapolating the simulated I-V graphs and the effects of both permittivity and temperature to the rectification properties are observed. The results obtained can assist the design of SSD to efficiently operate as microwave rectifier, especially in radio frequency harvesting application.

Design of DC high voltage and low current power supply using Cockroft-Walton (C-W) voltage multiplier

The high voltage DC power supply widely used for space communication and for industry consist of multistage rectifier circuit. To produce 6KV output voltage, Cockroft-Walton multiplier circuits are applied by reducing number of stages from 1200 into 32 stages without using transformer. With the implementation of this technique, it can minimize the volume of the circuit to be integrated on a single chip and it also can reduce associated power loss in the circuit. By eliminating the transformer method, cost and size for making Cockroft-Walton Voltage Multiplier are reduced. Specification need to be considered for designing a multiplier is size of component must use within the range of expected load current and output voltage The details description of the simulation, design, development and implementation of this works are done using Cadence PSPICE software. Results are present in term of the performances and efficiency.

Rectification performance of self-switching diode in various geometries using ATLAS simulator

Characterization on a planar nano-device, known as self-switching diode (SSD) aimed for rectification application at high frequencies is reported. Simulation has been conducted on InGaAs-based SSD with 70 nm L-shaped channels using two-dimensional (2D) ATLAS simulator. The current-voltage (I-V) characteristic of the device is found asymmetrical, similar to I-V behavior of a diode. The structure geometries of the channel are varied in term of channel length, channel width, and trenches width to observe the I-V behavior of the device. Furthermore, the curvature co-efficient of the SSD has been evaluated by extrapolating the simulated I-V graphs and the rectification performance of each configuration has been observed and concluded. The results obtained can assist the optimization in the design of the SSD to efficiently operate as microwave rectifier, especially in radio frequency harvesting application.

Rectification performance of self-switching diodes in silicon substrate using device simulator

A planar nanodevice, known as the self-switching diode (SSD) has been demonstrated to rectify electromagnetic signals at microwave and terahertz frequencies. This diode has a non-linear current-voltage (I-V) characteristic due to the structure of the device which consists of asymmetric nanochannel. To further explore the properties of SSD rectifiers, in this work, silicon-based SSDs with different dielectric materials that filled up the trenches of the devices were simulated using ATLAS device simulator under the temperature range of 250 K-500 K. The results showed that the rectification performance of the SSDs was deteriorated with increasing temperature for all dielectric materials which might be due to the thermal-activated electronic transport behavior of the devices.

Hydrophilicity Characterization on Cleaned Bonded Silicon Based Surface

This paper reports on the contact angle measurement analysis on a silicon based surface for anodic bonding process cleaned by three distinct cleaning processes. The three cleaning solutions tested in this experiment were RCA, piranha and acetone. Water Droplet Test (WDT) was done to analyze the contact angle of micro droplet on sample surface. It can be done by dropping a droplet of water in constant volume at the fixed height and angle. Only RCA process constantly decreases the contact angle value after cleaning. The compilations of data strongly proved that all samples become hydrophilic after RCA cleaning process. Samples which undergo piranha and acetone cleaning did not prove any characteristic of hydrophilic or hydrophobic surface after cleaning.

Methods of measurement of LTCC metallization thickness

Metallization provides electrical routing and serves as thermal via in LTCC (Low Temperature Cofired Ceramic) technology. High electrical and thermal conductivity is desirable. It is often achieved with the use of low electrical resistance materials, such as gold, silver and copper. The conductive paste made of these materials is expensive. Hence, the fabrication of LTCC has to be performance-wise and cost effective. The width, length and thickness of metallization are associated with the amount of conductor paste used. The thickness of metallization governs the functionality and performance of some components, such as resistor. In this paper, the physical attributes of LTCC substrate and its metallization was studied. Due to the constraint brought by the physical attributes of LTCC samples, various methods had been carried out. This paper also summarized the pros and cons of each method. The methods are limited to the equipment available.