Electrical characteristics of SRO-miss devices and their applications

The electrical characteristics of the Metal-Insulator-Semiconductor - Switch (MISS) device with Silicon-Rich-Oxide (SRO) as the semi-insulating material have been comprehensively studied at room temperature in an exploratory way. The SRO films were deposited by atmospheric pressure chemical vapour deposition (APCVD) at 650ºC with SiH(_4) and N(_2)O reactant gases and N(_2) carrier. The react ant gas phase ratio R(_o) varying from 0.09 to 0.25 and the deposition time varying from 0.6 to 2 min. Some preliminary investigations on SRO-MIS devices were also carried out in order to understand the electronic process in the structure. Various parameters which governed the switching behaviour of an MISS were investigated. In general the switching characteristics are similar to those of the tunnel oxide MISS. The geometrical dependence of the switching behaviour in the tunnel oxide MISS has been extended to the present device by looking at the effects of electrode area, junction area, electrode perimeters and of a metal guard ring. Other effects, such as SRO deposition time, work function difference, gold doping, heat treatment, light illumination and film ageing were also observed. The dynamic characteristic of the device was studied using a double pulse technique. The characteristics of the three-terminal SRO-MISS were studied in both forward and reverse bias. The former exhibited a thyristor-like characteristic and the latter a transistor-Hke characteristic. A preliminary study on the MIS-emitter transistor was carried out with different emitter areas. In general the characteristics are the same as for the equivalent tunnel oxide devices. However it was also found that if the n-type epilayer is very thin the transistor characteristics exhibits an N-type negative resistance. The negative resistance region of the two-terminal MISS has been shown to be stable and the stability has been analysed in terms of equivalent circuit elements. The reason for the stability is that the device also has an negative capacitance. This has been proved experimentally and it is a new property of the MISS structure which never been reported before. The negative capacitance has been measured as a function of electrode area, SRO type and light illumination. An important circuit application for the negative capacitance has also been suggested and demonstrate

Simulation study of side-by-side spiral coil design for micromagnetometer

Magnetic field measurement has many applications particularly in the field of navigation, military, space exploration, and medical. Among many magnetic devices, magnetometer is significant due to its capability of detecting direction and measuring strength of magnetic field. Through the years, many types of magnetometer had been invented with fluxgate magnetometer being one of the most well-known. In the advances of MEMS processing technology, fluxgate magnetometer is increasingly developed into micro-scale. Fluxgate magnetometer is made up of three major components consisting of sensing coil, driving coil and magnetic core. The physical characteristics of the coil structure play an important factor in miniaturization as well as in performance of the device. Therefore, investigations on the physical characteristics of the coils are relevant. In this paper, the side-by-side spiral coil structure is investigated in terms of its physical characteristics such as width of the coil and distance between successive coils. The aim is to observe and analyze the effects of varying the coil physical characteristics on certain important parameters that could influence the performance of the device. The work is done with the aid of FEM simulation software, where the physical characteristics of the coils were varied and simulated. With the simulated results, dimension of coils can be appropriately designed to optimize the performance of the device

Kajian Mengenai Kebersandaran Pembentukan Keadaan Potong Bawah Penjuru Terhadap Jenis Larutan Pemunar dalam Penghasilan Diafram Beralun Silikon

Kertas kerja ini membentangkan hasil kajian simulasi mengenai kesan jenis larutan pemunar ke atas keadaan potong bawah penjuru yang terhasil pada struktur-struktur penjuru cembung diafram beralun silikon (l00). Diafram yang terlibat dalam kajian ini dihasilkan dengan menggunakan teknik punaran anisotropik dengan larutan kalium hidroksida (KOH) dan larutan tetrametil amonia hidroksida (TMAH) sebagai pemunar. Kerja-keIja simulasi telah dijalankan dengan menggunakan perisian proses punaran anisotropik Intellisuite. Berdasarkan geometri struktur penjuru cembung terpunar dan kemunculan satah-satah baru silikon, diafram beralun silikon yang dipunarkan di dalam larutan TMAH didapati mengalami keadaan potong bawah penjuru yang lebih ketara berbanding diafram yang dipunarkan dalam larutan KOH

Self-Adjusting Electrochemical Etching Technique for Producing Nanoporous Silicon Membrane

This chapter presents the technique in producing the nanoporous silicon membrane using electrochemical etching technique. Electrochemical etching technique is a self-adjusting technique due to its ability to control transfer of ion to form pore by manipulating certain parameters. There are several parameters that have been manipulated to study the effect of each parameter to the pore formation by characterizing each component. The project starts with fabrication of silicon membrane and then continues with characterization of HF concentration, current density, doping and also alcohol diluents using field emission scanning electron microscopy (FESEM). The effect of each parameter is discussed in terms of pore size, pore formation and pore structure. Finally, the pore with size less than 100 nm and columnar structure has formed using this technique. The star-shaped structure is also formed through this experimental setup. Improved nanoporous silicon membrane can be applied for filtration and separating particles, especially in an artificial kidney

GaAs PHEMT single-ended mixers for 28 GHz applications

Mixers are key devices for front-end components in any transceiver of a communication system. The performance of a receiver rely heavily on the mixer operation in terms of its conversion loss (gain), noise figure, port-to-port isolation, intermodulation distortion and dynamic range. Microwave mixer can be designed by using Schottkybarrier diode or FET, either MESFET or HEMT. Using a FET rather than a diode as the non-linear element in a mixer has several advantages. Some of these include the possibility of achieving a conversion gain, using lower LO drive power and obtaining isolation between the signal ports of the FE

Graphene for biomedical applications:a review

Since its discovery in 2004, graphene has enticed engineers and researchers from various fields to explore its possibilities to be incepted into various devices and applications. Graphene is deemed a ‘super’ material by researchers due to its extraordinary strength, extremely high surface-to-mass ratio and superconducting properties. Nonetheless, graphene has yet to find plausible footing as an electronics material. In biomedical field, graphene has proved useful in tissue engineering, drug delivery, cancer teraphy, as a component in power unit for biomedical implants and devices and as a vital component in biosensors. Graphene is used as scaffolding for tissue regeneration in stem cell tissue engineering, as active electrodes in supercapacitor for powering wearable and implantable biomedical devices and as detectors in biosensors. In tissue engineering, the extreme strength of monolayer graphene enables it to hold stem cell tissues as scaffold during in-vitro cell regeneration process. In MEMS supercapacitor, graphene’s extremely high surface-to-mass ratio enables it to be used as electrodes in order to increase the power unit’s energy and power densities. A small yet having high energy and power densities cell is needed to power often space constrainted biomedical devices. In FET biosensors, graphene acts as detector electrodes, owing to its superconductivity property. Graphene detector electrodes is capable of detecting target molecules at a concentration level as low as 1 pM, making it the most sensitive biosensor available today. Graphene continues to envisage unique and exciting applications for biomedical field, prompting continuous research which results and implementation could benefit the general public in decades to come

Synthesis and characterization of carbon nano structures on Gallium Phosphate

Carbon nano structures were grown on Gallium Phosphate substrate by using Alcohol Catalytic Chemical Vapor Deposition (ACCVD) method. The aim of this paper is to study the structure and the morphology of the carbon nano structures growth on Gallium Phosphate. Gallium Phosphate is known as piezoelectric materials which are more stable and similar to quartz in its crystal structure. The ACCVD is chosen because of its simplicity and economical method for the growth of carbon nano structure. Mixture of ethanol and Iron Nitrate in a ratio of 1:25 was used as the catalyst to impregnate the carbon nano structures. The carbon nano structures were grown at 800oC. The ethanol liquid which was used as a carbon source was injected into the furnace tube with flow rate of 2.0 ml/min. The furnace was flowed by Argon gasses throughout the experiment. FE-SEM and EDX are used to investigate the morphology of the carbon structure. Finally Raman measurements have been performed and equipped with laser diode emitting at 632nm

Spin-on-Glass (SOG) based insulator of stack coupled microcoils for MEMS sensors and actuators application

A comprehensive study on the SOG (Spin-on-Glass) based thin film insulating layer is presented. The SOG layer has been fabricated using simple MEMS technology which can play an important role as insulating layer of stack coupled microcoils. The fabrication process utilizes a simple, cost effective process technique as well as CMOS compatible resulting to a reproducible and good controlled process. It was observed that the spin speed and material preparation prior to the process affect to the thickness and surface quality of the layer. Through the annealing process at temperature 425oC in N2 atmospheric for 1 h, a 750 nm thin SOG layer with the surface roughness or the uniformity of about 1.5% can be achieved. Furthermore, the basic characteristics of the spiral coils, including the coupling characteristics and its parasitic capacitance were discussed in wide range of operating frequency. The results from this investigation showed a good prospect for the development of fully integrated planar magnetic field coupler and generator for sensing and actuating purposes

Pencirian pertumbuhan lapisan nano grafin di atas elektrod antara digit superkapasitor MEMS

Superkapasitor MEMS khususnya dengan reka bentuk elektrod antara digit (IDE), telah menarik minat pada masa kini dalam bidang seperti bioMEMS, bioperubatan implan, peranti kuasa elektronik dan aplikasi berkuasa tinggi disebabkan kapasiti pengecasannya yang tinggi. Kajian ini membentangkan superkapasitor MEMS dengan lapisan nano grafin tumbuh di atas elektrod. Superkapasitor MEMS terdiri daripada silikon dioksida (SiO2), nikel, grafin, polipirol (Ppy) dan lapisan alkohol polivinil (PVA). Tumpuan diberikan kepada fabrikasi struktur lapisan nano grafin atas elektrod superkapasitor MEMS melalui beberapa proses seperti pemendapan wap kimia secara peningkatan plasma (PECVD), penyejatan alur e dan salutan pusing. Grafin tumbuh melalui proses PECVD selama 10 minit pada kuasa 40 Watt dan pada suhu antara 400°C dan 1000°C. Spektrum Raman menunjukkan puncak pada 1340 dan 1580 cm-1 mewakili jalur D dan G . Puncak 2D wujud dalam julat 2600 - 3000 cm-1. Nisbah bagi keamatan puncak 2D terhadap puncak G pada 1000°C adalah 0.43 menunjukkan kualiti yang baik bagi banyak lapisan grafin

Lithography method for selective area of CNTs growth

This paper presents the processes of fabrication method in the selective area of growth Carbon Nanotubes (CNTs) on the substrate with an Interdigitated (IDE) electrodes pattern using resist AZ1500. The substrate used in this work was Gallium Phosphate with Chromium (0.021μm) and Platinum (0.11μm) as the metal layer. The CNTS was grown in two different temperatures using chemical vapor deposition (CVD) with hydrogen as the process gas and benzene as the hydrocarbon. The most suitable temperature growth for CNTs in this work was found to be 800°C. In this study, CNTs were produced by CVD impregnated with iron nitrate (Fe(NO3)3·9 H2O) solution and Resist AZ1500 as the mask for the selective area grown. Maximum temperature for Resist AZ1500 was at 120°C. Therefore Iron Nitrate was used as the protector to protect the resist to be evaporated. The Resist AZ1500 and the Iron Nitrate were coated in different layer on the substrate using standard lithography method