Study of subthreshold behavior of FinFet

The study of subthreshold behavior of Metal Oxide Semiconductor Field Effect Transistor (MOSFET) is critically important in the case of submicron devices for the successful design and implementation of digital circuits. Fin Field Effect Transistor (FinFET) is considered to be an alternate MOSFET structure in the deep sub-micron regime. A 3D Poisson equation solver is employed to study the subthreshold behavior of FinFET. Based on potential distribution inside the fin, the appropriate band bending and the subthreshold value called the S-factor is calculated. It is observed that the S-factor of the device increases as the channel width, Tfin increases. This is attributed to the fact that the change in the band bending is less than the change in the applied gate voltage. This is only a first order analysis; hence the device is simulated in a device simulator Taurus. It is observed that the S-factor increases exponentially for channel lengths Lg \u3c 1.5Tfin. Further, for a constant Lg, the S factor is observed to increase as Tfin increases. An empirical relationship between S, Lg and Tfin is developed based on the simulation results, which can be used as a rule of thumb for determining the S-factor of devices

Synthesis of silicide nanomaterials using chemical vapour deposition method

Recent research has evidenced that nanotechnology may bring about a material revolution which sweeps through different scientific fields and leads to dramatic changes in the use of natural resources and our everyday life. Compared to their bulk counterparts, the nanomaterials may exhibit significantly improved physical properties by shrinking their size to nanometer scale. Metal silicide are distinguished by their features of combining advantages of both metals and semiconductors which promises superior performance various fields. Despite the progress in the synthesis methods of nanomaterials, it still remains a big challenge in controlled synthesis of 1D silicide nanostructures due to the difficulties of well-controlled synthesis conditions. In this study, synthesis process of NiSix and CoSix with different morphologies using CVD method have been analysed and determined. Synthesis of different structures of NiSix on a number of substrates has been investigated. The mechanisms behind the growth of these nanostructures have been studied for better understanding of the synthesis of these silicides. The detailed characterization techniques such as SEM, TEM and XRD were used

Uncooled Infrared Detector Featuring Silicon based Nanoscale Thermocouple

The main focus of this dissertation is to improve the performance of thermoelectric (TE) infrared (IR) detectors. TE IR detectors are part of uncooled detectors that can operate at room temperature. These detectors have been around for many years, however, their performance has been lower than their contesting technologies. A novel high-responsivity uncooled thermoelectric infrared detector is designed, fabricated, and characterized. This detector features a single standalone polysilicon-based thermocouple (without a supporting membrane) covered by an umbrellalike optical-cavity IR absorber. It is proved that the highest responsivity in the developed detectors can be achieved with only one thermocouple. Since the sub-micrometer polysilicon TE wires are the only heat path from the hot junction to the substrate, a superior thermal isolation is achieved. A responsivity of 1800 V/W and a detectivity of 2 ? 10^8 (cm. sqrt(Hz)W^?1) are measured from a 20?m x 20?m detector comparable to the performance of detectors used in commercial focal planar arrays. This performance in a compact and manufacturable design elevates the position of thermoelectric IR sensors as a candidate for low-power, high performance, and inexpensive focal planar arrays. The improvement in performance is mostly due to low thermal conductivity of thin polysilicon wires. A feature is designed and fabricated to characterize the thermal conductivity of such a wire and it is shown for the first time that the thermal conductivity of thin polysilicon films can be much lower than that of the bulk. Thermal conductivity of ~110nm LPCVD polysilicon deposited at 620C is measured to be ~3.5W/m.K

Bottom-up 1-D nanowires and their applications

Master'sMASTER OF ENGINEERIN

Metal gate with high-K dielectric in Si CMOS processing

Ph.DDOCTOR OF PHILOSOPH

Laser direct written silicon nanowires for electronic and sensing applications

Silicon nanowires are promising building blocks for high-performance electronics and chemical/biological sensing devices due to their ultra-small body and high surface-to-volume ratios. However, the lack of the ability to assemble and position nanowires in a highly controlled manner still remains an obstacle to fully exploiting the substantial potential of nanowires. Here we demonstrate a one-step method to synthesize intrinsic and doped silicon nanowires for device applications. Sub-diffraction limited nanowires as thin as 60 nm are synthesized using laser direct writing in combination with chemical vapor deposition, which has the advantages of in-situ doping, catalyst-free growth, and precise control of position, orientation, and length. The synthesized nanowires have been fabricated into field effect transistors (FETs) and FET sensors. The FET sensors are employed to detect the proton concentration (pH) of an aqueous solution and highly sensitive pH sensing is demonstrated. Both top- and back-gated silicon nanowire FETs are demonstrated and electrically characterized. In addition, modulation-doped nanowires are synthesized by changing dopant gases during the nanowire growth. The axial p-n junction nanowires are electrically characterized to demonstrate the diode behavior and the transition between dopant levels are measured using Kelvin probe force microscopy

Vertical Silicon Nanowire Gate-All-Around Tunneling Field Effect Tranistors for Future Low Power Nanoelectronics

Master'sMASTER OF ENGINEERIN

Cutting Edge Nanotechnology

The main purpose of this book is to describe important issues in various types of devices ranging from conventional transistors (opening chapters of the book) to molecular electronic devices whose fabrication and operation is discussed in the last few chapters of the book. As such, this book can serve as a guide for identifications of important areas of research in micro, nano and molecular electronics. We deeply acknowledge valuable contributions that each of the authors made in writing these excellent chapters