Talal S. Al-Harbi

A new technique of cancelation of the MOSFET leakage currents and parasitic capacitances

Abstract The paper presents a new topological technique to be used with MOSFETs to appreciably minimize their channel and drain leakage currents (by a factor of 4) and parasitic capacitances (about 10 times smaller). It also enhances the channel inversion rate due to the channel potential distribution and leads consequently to greater device-switching speeds (10 times greater). This technique will allow a smaller device to device separation without fearing from any proximity effects. It is based on the creation of a transverse lateral field which is oriented so as to keep the channel electrons within its potential-well and to reduce the channel to substrate depletion layer width. A detailed study and characterization of the new technique is comprised.

Threshold-voltage instability caused by the hot-carrier substrate current in MOSFETs

The need for precise modelling and evaluation of the threshold-voltage shift and instability in ultra-short channel MOSFETs has increased considerably, due to advances in technology and the introduction of novel high-complexity applications. The hot carrier substrate current is shown to be one of the most important parameters which appreciably shifts the threshold voltage and affects its instability. Two analytical models are considered, one for predicting the hot-carrier substrate current and the other to evaluate the threshold-voltage shift and investigate its dependence on the current level and the devices mode of operation.

Influence of aluminium concentration in Zn0:9V0:1O nanoparticles on structural and optical properties

Abstract The (V,Al) co-doped ZnO nano-structured powders (Zn0.9-xV0.1AlxO, where x = 0.02, 0.03 and 0.04) were synthesized via the sol-gel technique and their structural and optical properties were investigated. The effect of Al concentration on the structural and optical properties of the Zn0.9-xV0.1AlxO nanopowders was studied using various techniques. The XRD patterns indicate that the samples have a polycrystalline wurtzite structure. The crystallite size increases with increasing the Al content and lies in the range of 23 to 30 nm. The lattice strain, estimated by the Stokes-Wilson equation, decreases when Al content increases. SEM and TEM micrographs show that Zn0.9-xV0.1AlxO powders are the agglomeration of nanoparticles having spherical and hexagonal shapes with dimensions ranging from 20 to 30 nm. FT-IR spectra show a distinct absorption peak at about 500 cm-1 for ZnO stretching modes and other peaks related to OH and H2O bands. Raman spectra confirm the wurtzite structure of the Zn0.9-xV0.1AlxO nanoparticles. The direct band gaps of the synthesized Zn0.9-xV0.1AlxO nanopowders, estimated from the Brus equation and the crystallite sizes deduced from XRD, are around 3.308 eV. The decomposition process of the dried gel system was investigated by thermal gravimetric analysis (TGA).

Modelling and characterization of TG-MOSFET for precision VLSI applications

The paper comprises an investigation and modelling of a new short channel trapezoidal-formed gate MOS field effect transistor (TG-MOSFET). The new device is characterized by a reduced leakage current (approximately four times smaller), a small parasitic capacitance (approximately ten times smaller) and a fast switching response. It also provides a relatively larger gate current at appreciably smaller channel current and smaller power dissipation than that of the traditional rectangular gate MOSFETs. Analysis also showed that the trapezoidal gate form of the new device helps to reduce its channel-length modulation noise by a factor of 25. These features are needed for precision VLSI applications. Measurements have been performed on devices of l-4µm channel length, 400 to 1200 A˚ oxide thickness and channel sides steepness of up to 6 and were seen to be in good agreement with the theory.

Investigation of a New Technique for Adaptive Cancellation of Noise in MOSFET Op. Amps.@@@دراسة وتبيان تجريبي لتقنبية جديدة للإلغاء المتوائم للضوضاء في المكبرات التشغيلية عالية التكبير والمصنوعة بتكنولوجيا م و س

The paper presents a new technique for adaptive cancella- tion of noise in MOSFET IC operational amplifiers. It employs two operational amplifiers, one is passive with its inverting and noninvert- ing inputs short circuited. This operational amplifier is only responsi- ble to amplify its equivalent input noise and to give a proportional output voltage. The second operational amplifier is active and is used to amplify the signal to be processed together with its equivalent input noise and gives, thus, a proportional output voltage. The two opera- tional amplifiers are coupled to each other through a common floating gate so that the noise of the passive amplifier is subtracted from the input of the second one and makes it, therefore, noise-free (~lnV/√  Hz or 0.1 µV rms within 2.5 kHz bandwidth) over a wide variety dynamic range of input voltage (~120 dB) and ambient temperature. A feed- back loop is added to improve the amplifier linearity (better than 2%). The standard 2 µm CMOS technology is used for the realization of the proposed noise-free operational amplifier.