Sanna Taking

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.

Indoor navigation and localisation application system

This project is dedicated towards the designing and developing of an indoor positioning tracking application system with the most optimum characteristics. This is because the Global Positioning system (GPS) is not suitable to be used indoors due to signal lost within contact of building walls. The indoor positioning system is based on the application of Wi-Fi access points found abundantly in smart phones and buildings. Note that the main goal of this project is maintaining both the budget and power consumption the lowest value possible while completing the project within a stipulated time. The system has two main functions which are to provide localisation and navigation services.

Effects of Indium (In) to the Efficiency Tandem Cell Ga1-xInxP/Silicon for Solar Cell Application

In this paper, the contribution of Indium (In) to the Gallium Phosphide (GaP) composition of solar cell was investigated to know the effectiveness of the In when its being substitute to GaP layer on the top layer of Silicon (Si) substrate. The substitution was made to the Ga1-xInxP for the range of (0≤x≤0.5). The highest efficiency was 10.1235% for x=0.5 for the Ga1-xInxP. In contribution shows a higher efficiency compared to single layer GaP which only about 5.40608%. As the x composition increased, the efficiency becomes higher for each composition increment. The rate of efficiency, increased about 88% and improves current density with a value up to 13.1134mA/cm2.The efficiency obtained in this work is considerably high using simulation tools compared to the previous record for InGaP/Silicon reported in Feb 2014 about 6~11.2% by fabrication method.

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.

Effect on different geometric dimensions of metal-oxide-semiconductor capacitor by using TCAD simulation

This paper reports on the design, implementation, and characterization of a trench-filled capacitor in complementary Metal-Oxide-Semiconductor (CMOS) grade silicon. In order to achieve high capacitance value in MOS capacitor, trench technology is applied to improved capacitance. The simulation executed by using Synopsyss Sentaurus TCAD. A C-V measurement was done between two different structures of MOS capacitor which are using planar and trench technology. A MOS capacitor with planar technology achieved 4.5 fF meanwhile trench technology achieved a much higher capacitance which is 1.325 pF. A test of varied trench has also been carried out to verify the basic fundamentals of MOS capacitor. It shows that a deeper trench helps to increase higher capacitance.

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.

The Comparison Between Gallium Arsenide and Indium Gallium Arsenide as Materials for Solar Cell Performance Using Silvaco Application

The work presented in this paper is about the development of single and multilayer solar cells using GaAs and InGaAs in AM1.5 condition. The study includes the modeling structure and simulation of the device using Silvaco applications. The performance in term of efficiency of Indium Gallium Arsenide (InGaAs) and GaAs material was studied by modification of the doping concentration and thickness of material in solar cells. The efficiency of the GaAs solar cell was higher than InGaAs solar cell for single layer solar cell. Single layer GaAs achieved an efficiency about 25% compared to InGaAs which is only 2.65% of efficiency. For multilayer which includes both GaAs and InGaAs, the output power, Pmax was 8.91nW/cm² with the efficiency only 8.51%. GaAs is one of the best materials to be used in solar cell as a based compared to InGaAs.

Ferroelectric and relaxor ferroelectric to paralectric transition based on Lead Magnesium Niobate (PMN) materials

First ferroelectric materials were found in Rochelle salt was in a perovskite structure. Lead Magnesium Niobate (PMN) is a perovskites with a formula of PbMg1/3Nb2/3O3 (PMN) and are typical representatives for most of all ferroelectrics materials with relaxor characteristic. It posses high dielectric permittivity which nearly ~ 20,000[ with a broad dielectric permittivity characteristic, known as relaxor ferroelectric below room temperature. Some of the researcher might think that the transition from relaxor ferroelectric to paraelectric is similar to the characteristic as observed from ferroelectric to paraelectric, but it is not necessary. The puzzling is how do we categorise them. How is the domain structure look like typically in ceramic materials.