Manoj Khanna

Analytical two-dimensional modeling for potential distribution and threshold voltage of the short-channel fully depleted SOI (silicon-on-insulator) MOSFET

Abstract A two-dimensional analytical model for fully depleted SOI MOSFETs is presented. An extensive study of potential distribution in the silicon film is carried out for non-uniform doping distribution and extended to find an expression for threshold voltage in the sub micrometer region. The results so obtained are verified with experimental data. The present model calculates a critical gate voltage (for short channel fully depleted SOI devices) beyond which gate losses its control on drain current. The advantages of SOI MOSFETs over the bulk counterparts are explained on the basis of drain induced barrier lowering [DIBL]. It is also shown that the threshold voltage for the thin film SOI MOSFET is less than that of bulk MOSFET. The short-channel effects, DIBL and threshold voltage reduction, are well predicted in the present model.

Cut off frequency and transit time analysis of lightly doped drain (LDD) MOSFETs

Abstract Analytical model for the transconductance, cut off frequency, transit time and fringing capacitance of LDD MOSFETs is presented with a simple approach. The analysis is carried out considering the LDD device as a conventional MOSFET with a series resistance [Z.-H. Liu et al., Threshold voltage model for submicrometer MOSFETs. IEEE Trans Electron Devices 1993; ED-40: 86–94] and a simple closed form expressions for cut off frequency and transit time is obtained. The total gate capacitance, i.e. the geometric and fringing capacitance, is calculated for both LDD and non-LDD devices and lower fringing capacitance is reported in LDD devices. Lower cut-off frequencies and higher transit time are reported in LDD devices for the same channel length.

A device model for an ion-implanted MESFET with Half-Pearson and Half-Gaussian distribution under post-anneal conditions

A model is developed for an ion-implanted long channel silicon MESFET in terms of Half-Pearson-IV and Half-Gaussian distribution. Reasonable approximations have been made to obtain simplified solution of Poissons equation. It is seen that approximate Gaussian profile and exact Half-Pearson-IV Half-Gaussian profile gives exactly the same I/sub d/-V/sub d/ curves. It is also observed that the threshold voltage gets reduced in the later case. >

Narrow gate effect on depletion mode insulated gate field effect transistor

Abstract An analytical method is presented to predict the I d − V d characteristics and threshold voltage of narrow gate depletion mode MOSFET. It is shown that the threshold voltage expression developed is simple and valid for all gate width. The generalized expressions of threshold voltage and drain current in linear and saturation region are compared with the experimental results of wide channel depletion mode MOSFETs and the increase of threshold voltage and reduction of drain current with gate width is established as predicted by other experimental/simulation results.

Analytical theory of two-dimensional charge sheet model for short channel MOSFETs under non linear charge control

Abstract An analytical theory of two-dimensional charge sheet model of short channel IGFETs under non-linear charge control which geometrically takes into account the two-dimensional edge effect is developed. This theory includes the effects of non-uniform doping and uses the charge sheet model approach. Since the diffusion current plays an important role in subthreshold and saturation regions, the model also takes it into account along with the drift current. The model thus proposed is more accurate than the earlier models as it includes the effects of diffusion and leads to an exact analytical expression for the device current. The results obtained are compared with those of uniform doping. It is found that the current magnitude starts out greater for non-uniform doping and as the gate voltage is increased, the increase in current slows down and approaches to that of uniform doping.

One dimensional FexCo1-x nanowires; ferromagnetic resonance and magnetization dynamics

Soft magnetic nanowires (NWs) are widely used for microwave and mm-wave components. The investigation of magnetization damping behavior of NWs have attracted great interest due to large influence of loss to the device, like integrated microwave device, magnetic sensors, and magnetic random access memory. With increasing operational frequency and degree of integration, the requirements to characterize 1-dimensional NWs become increasingly high. The purpose of this work is to study the magnetization dynamics in FexCo1-x NWs. A series of FexCo1-x (x=0, 0.25, 0.5, 0.75, 1) NWs were grown by controlled electro-deposition. By adjusting FexCo1-x concentration (x=0 to 1), the saturation magnetization, increased more than 20%. Ferromagnetic resonance (FMR) both in field and frequency sweep mode are employed to characterize the NWs in flip-chip geometry. It is observed that FMR field (Hr) increases with increase in applied frequency. At a fixed frequency, Fe NWs resonate at a lower field than the Co substituted NWs...

An empirical fringing capacitance dependent threshold voltage model for non-uniformly doped submicron MOSFETs

Abstract A simple and closed-form expression for the threshold voltage of non-uniformly doped submicron MOSFET is developed. The main features of this model are: (1) non-equipotential surface of the device which includes the non-uniformity effect along the channel; (2) charge screening effects to explain the weak substrate bias dependence for short channel devices; and (3) total gate capacitance of MOS structures (the geometric capacitance and the fringing capacitance which is calculated using the conformal transformation considering the effects of electrode thickness and lateral gate dimensions). Comparisons between the present model and experimental data show good agreement for a wide range of channel lengths and applied substrate biases.

Microwave monolithic filter and phase shifter using magnetic nanostructures

Monolithic Microwave Integrated Circuit (MMIC) have major impact on the development of microwave communication technology. Transition metal based ferromagnetic nano-wired (FMNWs) substrate are of special interest in order to fabricate these MMIC devices. Their saturation magnetization is comparatively higher than ferrites which makes them suitable for high frequency (>10 ∼ 40 GHz) operation at zero or a small applied magnetic field. The CoFeB nanowires in anodic alumina templates were synthesized using three-electrode electro-deposition system. After electro-deposition, 1μm thick Cu layer was sputtered on the top surface of FMNW substrate and lithography was done to design microstrip lines. These microstrip transmission lines were tested for band-stop filters and phase shifters based on ferromagnetic resonance (FMR) over a wide applied magnetic field (H) range. It was observed that attenuation and frequency increase with the increase of magnetic field (upto 5.3 kOe). For phase shifter, the influence of magnetic material was studied for two frequency regions: (i) below FMR and (ii) above FMR. These two frequency regions were suitable for many practical device applications as the insertion loss was very less in these regions in comparison to resonance frequency regions. In the high frequency region (at 35 GHz), the optimal differential phase shift increased significantly to ∼ 250 deg/cm and around low frequency region (at 24 GHz), the optimal differential phase shift is ∼175 deg/cm at the highest field (H) value.

Awareness and Sensitivity of Mobile Phone Consumers on Electronic Waste in Delhi-NCR Region

Information technology has become a part of everyday life for people from a vast cross section of the society in Indian and international perspective. This has also resulted into unimaginable accumulation of Waste from electrical and electronic equipment, also referred as WEEE. In India, there are approximately 952 million mobile subscribers. Electronic waste (e-waste) is becoming a very significant contributor to the municipal waste in the cities. It holds concern among researchers as e-waste has valuable recyclable resources and also risks as hazardous waste. These materials require not only special handling but also proper disposal and recycling methods to avoid their deleterious effects on human health and environment. Some of the hazardous materials are for example arsenic which is poisonous, beryllium which is carcinogenic and Brominated flame retardants which are potentially neurotoxins. Therefore, it is the need of the hour to educate people about e-waste and their proper disposal. The study is based upon certain assumptions that the rapid and low cost development of electronic device technology is taking place in India. People prefer to buy newer electronic gadgets rather than to repair the older one due to the higher cost of repair. Considering that mobiles are the fastest growing e-consumables, this paper attempts to study the consumption pattern, awareness in general and gender-based awareness about electronic waste among the users of Delhi-NCR region. Study has also been carried out to know about the age at which people start using mobile phones.

Analysis of Silicon Clad Optical Waveguide for High Extinction Ratio TE/TM Pass Polarizers using Resonant Coupling between Guided Modes and Lossy Modes

Attenuation characteristics of a planar silicon-clad ion exchange glass waveguide structure are investigated theoretically at the optical wavelength of 0.6328 μm. An oscillatory behaviour of the attenuation curves is noticed in the proposed four layer structure. It is observed that by varying the thickness of silicon cladding layer, the TE or TM propagating modes may be selectively attenuated. This characteristic can be used to design a high extinction ratio and low insertion loss TE or TM pass polarizer. For the analysis of both polarizations, effective indices are calculated at various thicknesses of Silicon cladding layer using Transfer Matrix Method (TMM). At an optimum Silicon thickness, polarizer parameters like insertion loss and extinction ratio are calculated and tabulated. This paper provides rigorous analysis for silicon clad waveguide polarizer parameters for TE as well as TM polarization using same structure. A TM pass polarizer with extinction ratio of about 690 dB and insertion loss of about 2.8 dB and a TE pass polarizer with extinction ratio of about 289 dB and insertion loss of about 1.5 dB is proposed for a length of 1mm.