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In this paper, we present a review on the development in modeling of transmittance and tunneling current through a high-K dielectric gate stack of a metal-oxide- semiconductor (MOS) capacitor by considering the coupling of transverse and longitudinal energies of an electron represented by an electron phase velocity in the gate and anisotropic masses. In order to obtain the electron transmittance and tunneling current, Airy- and exponential wavefunctions were utilized as analytical approaches. A transfer matrix method (TMM) was used as a numerical approach as a benchmark to find the best analytical approach in calculating the transmittance and tunneling current. It was shown that the Airy wavefunctions approach was a better analytical expression to calculate the transmittance and tunneling current. Furthermore, the tunneling currents computed under Airy wavefunction approach were compared to the measured ones to examine the model. It was shown that the calculated tunneling currents are fitted well by the measured ones. It was also shown that the model could be used in designing a high speed MOSFET with low tunneling current.

We have studied tunneling current in a p-n junction based on armchair graphene nanoribbon (AGNR) by using the relativistic Dirac equation and a transfer matrix method (TMM). The electron wave function was derived by solving the relativistic Dirac equation. The TMM, which is a numerical approach, was used to calculate electron transmittance and the tunneling current. The results showed that the tunneling current increases with the bias voltage. On the other hand, the tunneling current increases with the decreases in the electron incidence angle and temperature. Moreover, the increases in the AGNR width and electric field in the p-n junction result in the increase in the tunneling current.

Tunneling current in an armchair graphene nanoribbon (AGNR) tunnel field-effect transistor (TFET) was modeled. A linear equation was employed in describing a potential distribution within the AGNR due to its simplicity. A parabolic dispersion and an electron effective mass obtained by approximating kx 0 to the parabolic dispersion were applied to AGNR. In order to obtain electron transmittance, electron wavefunctions in AGNR were based on Airy functions. The obtained transmittance was then applied to calculate the tunneling current by employing the Landauer formula. The calculated results showed that the tunneling current increases with the AGNR width. It was also shown that the tunneling current increases as temperature decreases. In addition, the gate voltage influences the saturation condition of tunneling current in AGNR TFETs.

Electron tunneling current in an isotropic metal-oxide-semiconductor (MOS) capacitor with a high-κ dielectric stack has been studied by considering the effect of charge trapping. The transmittance was analytically calculated by employing an Airy-wavefunction approach and including a coupling term between the transverse and longitudinal kinetic energies which is represented by an electron phase velocity in the gate. The transmittance was then applied to obtain tunneling currents in isotropic n+poly-Si/HfSiOxN/trap/SiO2/Si (100) MOS capacitors for different electron gate phase velocities and trap depths and widths. The calculated results show that the transmittance and tunneling current increase as the electron gate velocity decreases. In addition, the increase in the trap depth and width enhances the tunneling current.

Drain current in an armchair graphene nanoribbon field effect transistor (AGNRFET) has been quantum mechanically modeled. The transfer matrix method (TMM) was employed to obtain the electron transmittance, and the obtained transmittance was then utilized to calculate the drain current by using the Landauer formula. The calculated results showed that the drain current increases with the gate and drain voltages. It was also shown that the threshold voltage for the device is around 0.3 V. In addition, the AGNR width influences the drain current of AGNRFET.

We present a compact model of the gate tunneling current in cylindrical surrounding-gate (SG) metal-oxide-semiconductor field-effect transistors (MOSFETs) based on quantum mechanical correction. The model is physics-based and is given in an analytical closed form. We start by deriving a quadratic approximation of the quantum electrostatic potential with the two lowest energy levels using quantum perturbation theory. In addition, small-diameter cylindrical SG MOSFETs can be described excellently by taking both structural and electrical confinement effects into account. A self-consistent Schrodinger-Poisson simulation was used as a benchmark to assess the proposed model. It was found that the calculated gate tunneling currents determined using the model matched well with the corresponding currents derived using self-consistent calculations. The model is thus useful for fast analysis of gate tunneling currents within the context of a circuit simulator.

Abstract. Soils are increasingly threatened by spillage of petroleum products such as petrol, diesel fuel, gasoline at oil refineries, underground storage tanks and pump stations pipelines. This study aims to investigate the effectiveness of Pseudomonas putida as oil-biodegradable agent in soil contaminated with diesel (D100). The effectiveness on bioremediation have been conducted by examined several physico-chemical tests on diesel-contaminated soil before and after seeding with P. putida. The spillage stimulation of D100 was conducted at laboratory scale for 24 days of incubation time. The results show that the bioremediation treatment able to remove up to 82%, 55%, 48%, and 34% of nitrogen, total organic carbon, phosphate, sulfate and, respectively. The pH of soil sample was changed from pH 7.8 (Day 0) to 6.78 (Day 24) after the treatment. Meanwhile, the moisture content in the sample has increased from 39% (Day 0) to 59% (Day 24). All of these results show the good indication of quality improvement of polluted soil after treated with P. putida. It is apparent from the acquired results that the application of P. putida is suitable as effective microorganism and potentially exploits as useful diesel-soil biodegradable agent in polluted soil.

The commercialization of biodiesel/diesel blends on the market can cause environmental damages due to spills. This study aims to investigate the effectiveness ofPseudomonas putidaas oil-biodegradable agent in soil contaminated with biodiesel/diesel blend (B20). The effectiveness on bioremediation have been conducted by examined several physico-chemical tests on biodiesel/diesel-contaminated soil before and after seeding ofP. putida. The spillage stimulation of B20 was conducted at laboratory scale for 24 days of incubation time. The results show that the bioremediation treatment able to remove up to 82%, 77%, 16%, and 10% of nitrogen, phosphate, sulfate and total organic carbon, respectively. The pH of soil sample was changed from pH 7.45 (Day 0) to 7.25 (Day 24) after the treatment. Meanwhile, the moisture content in the sample has increased from 44.11% (Day 0) to 50.35% (Day 24). All of these results show the good indication of quality improvement of polluted soil after treated withP. putida. It is apparent from the acquired results that the application ofP. putidais suitable as effective microorganism and potentially exploits as useful oil-soil biodegradable agent in polluted soil.

The performance of SnO2/SiO2/n-Si solar cells was studied by considering various transport mechanisms including minority-carrier diffusion, carrier recombination, and tunneling through insulating layer. The tunneling current through the SiO2 layer was obtained by employing the Airy-wavefunction approach. The efficiency was calculated to determine the performance of the cells under AM1 illumination for different values of insulating layer thickness, interface state density, hole life-time, doping density of silicon substrate, and cell thickness. It was shown that the efficiency increases as the insulating layer becomes thinner due to the decrease of short-circuit current. It was also shown that the efficiency increases as the doping density increases up to 6x1022/m3 and it then decreases for higher doping densities. As the interface state density decreases, the efficiency becomes higher. In addition, the increases in the hole lifetime and cell thickness enhance the efficiency of the solar cell.

In this study, atomic simulation for graphene growth on Ni (100) at initial stage via chemical vapor deposition method has been developed. The C-C atoms interaction was performed by Terasoff potential mean while Ni-Ni interaction was specified by EAM (Embedded Atom Modified). On the other hand, we used very simple interatomic potential to describe Ni-C interaction during deposition process. From this simulation, it shows that the formation of graphene is not occurs through a combined deposition mechanism on Ni substrate but via C segregation. It means, Ni-C amorphous is source for graphene growth when cooling down of Ni substrate. This result is appropriate with experiments, tight binding and quantum mechanics simulation.

As Malaysia is rapidly transforming into a knowledge-based nation, our society has realized the importance of lifelong learning. Thus, continuing education development is needed to accommodate its increasing demand for skilled personnel. To achieve this, UTMSPACE of Universiti Teknologi Malaysia (UTM) incepted in 1994, has expanded its professional programmes through the establishment of Professional Development Unit (UPP) in 2004. Among UPP's major functions include event management, and educate individuals with knowledge, skills, and ability in dealing with the challenges of current technology. This paper highlights the learning experience and challenges faced by UPP in managing UTMSPACE 's professional development and training programmes. In particular, the strategic and synergize efforts taken both by UTMSPACE and UTM towards gaining prestigious brand in continuing education in Malaysia .

Graphene has a high potential for use in electronic devices because it has a unique characteristic, electrons in massless grasses and has a speed close to the speed of light. Graphene conductivity at temperature space is 40 000 cm2V-1s-1 in the air. In addition, thermal conductivity can reach 2 800 Wm-1K-1. The mechanical properties of graphene are very strong and flexible, and optical properties it has a white light transmittance of 95%. Therefore, graphene is suitable for transparent screen and the flexible electrode. The energy band gap of monolayer graphene can be changed by reducing the size, as for the band gap of bilayer graphene was affected by symmetry between two layers. So, it is interesting to research the band gap characteristics of bilayer armchair graphene nanoribbon (AGNR). In this paper, we have calculated the band gap of bilayer graphene and bilayer AGNR in various parameters such as band width and symmetry between two layers. The method used is tight binding method by only taking into account its nearest neighbors only. The results obtained from this simulation show that the band gap will be more open if asymmetry of the structure bilayer graphene is increasing and the band gap of AGNR will be more open if ribbon width decreased, is not affected by asymmetry.

The Dirac electron tunneling current in an n-p-n bipolar transistor based on armchair graphene nanoribbon (AGNR) has been modeled. The electron wavefunction was derived by employing the relativistic Dirac equation. The transmittance was derived by using the transfer matrix method (TMM). The Landauer formula was used to calculate the Dirac electron tunneling current. The results showed that various variables such as base-emitter voltage, base-collector voltage and the AGNR width affect the Dirac electron tunneling current. It was found that the Dirac electron tunneling current increases with increasing base-emitter and base-collector voltages. Moreover, the increase in the AGNR width results in the increase in the Dirac electron tunneling current.

Simulation of tunnel current flowing in a p-n diode made from armchair graphene nanoribbons (AGNRs) was built. The diode is composed of p-type and n-type AGNRs and bandgaps of the AGNRs are obtained by using a tight binding method. The bandgaps are required to describe a potential profile having a potential barrier of the diode. Transmittance of electrons tunneling through the potential barrier is then calculated by employing Airy wavefunctions. Gaussian quadrature method, which is a numerical approximation, is used to obtain tunnel current in the diode. All steps are visualized by using the graphical user interface of Matlab.

In this paper, we discuss the electron transmittance and tunneling current in high-k-based-MOS capacitors with trapping charge by including the off-diagonal effective-mass tensor elements and the effect of coupling between transverse and longitudinal energies represented by an electron velocity in the gate. The HfSiOxN/SiO2 dual ultrathin layer is used as the gate oxide in an n+ poly- Si/oxide/Si capacitor to replace SiO2. The main problem of using HfSiOxN is the charge trapping formed at the HfSiOxN/SiO2 interface that can influence the performance of the device. Therefore, it is important to develop a model taking into account the presence of electron traps at the HfSiOxN/SiO2 interface in the electron transmittance and tunneling current. The transmittance and tunneling current in n+ poly- Si/HfSiOxN/trap/SiO2/Si(100) capacitors are calculated by using Airy wavefunctions and a transfer matrix method (TMM) as analytical and numerical approaches, respectively. The transmittance and tunneling current obtai...

An analytical expression of direct tunneling time of an electron through a nanometer-thick trapezoidal barrier has been derived. It is found that the direct tunneling time is independent of the thickness of the SiO2 barrier for the SiO2 layers thicker than 1 nm, which are used in advanced MOS (metal-oxide-semiconductor) devices. By applying a voltage to the barrier layer, the direct tunneling time becomes shorter than that obtained without the applied voltage. The nonparabolic energy-momentum dispersion of the barrier layer increases the direct tunneling time as compared to the parabolic one. However, the nonparabolic effect is negligible for high electron energy. It is also shown that the tunneling time obtained by the phase time is shorter than that calculated by the semiclassical approach for high electron energy. However, both of the calculated tunneling times have not been able to explain the reason why the calculated tunneling time are orders of magnitude shorter than the highest time resolution achievable in the siliconbased MOS devices. � 2005 Elsevier Ltd. All rights reserved.

In this study, we report an analytical calculation of electron transmittance and polarized tunneling current in a single barrier heterostructure of a metal-GaSb-metal by considering the Dresselhaus spin orbit effect. Exponential function, WKB method and Airy function were used in calculating the electron transmittance and tunneling current. A Transfer Matrix Method, as a numerical method, was utilized as the benchmark to evaluate the analytical calculation. It was found that the transmittances calculated under exponential function and Airy function is the same as that calculated under TMM method at low electron energy. However, at high electron energy only the transmittance calculated under Airy function approach is the same as that calculated under TMM method. It was also shown that the transmittances both of spin-up and spin-down conditions increase as the electron energy increases for low energies. Furthermore, the tunneling current decreases with increasing the barrier width.

In the present work, we report the preparation of BCNO/SiO2 phosphor synthesized using a microwave-assisted method. This method allows a lower temperature and a shorter reaction time than simple heating (furnace). The phosphors were prepared from precursors containing, boric acid, urea, citric acid and SiO2 nanoparticles. To These precursors, silica nanoparticles were added at various concentrations from 0 to 5 %wt. The emission wavelength produced by the phosphor was varied by varying the fraction mass of the silica that were added to the precursors. The results showed that higher photoluminescence (PL) intensity was produced by the BCNO/SiO2 with 3 %wt silica addition. The novelty of this research is using microwave heating for BCNO/SiO2 synthesis, which is usually conducted using a simple heating method.

A tunnelling field-effect transistor (TFET) based armchair graphenenanoribbons (AGNRs) with variation of uniaxial strain has been modeled. Bandgap of strained AGNR estimated by an extended tight binding method is applied to obtain electrical characteristics of a TFET under the quantum capacitance limit device approximation. Furthermore, the electron transmittance is calculated by utilizing the WKB (Wentzel–Kramers–Brillouin) approach. The obtained transmittance is then used to calculate the drain current by employing the Landauer formula. The results show that strain parameter has significant effect on the current. In other words, the electrical characteristics of AGNR TFET can be tuned by the strain of AGNR.

This study concerns hybrid Monte Carlo and molecular dynamics (MD/MC) methods involving a recipe for creating nickel carbide that can be applied to the graphene growth process. The time-stamped force-bias Monte Carlo (tfMC) method was used for taking care of the bond switching (BS) rate due to the concentration of carbon atoms in the nickel catalyst. It was found that the hybrid MD/MC method promotes the nickel carbide system to vibrational bond switching. This study also revealed that carbon atoms in metal catalyst are not spread randomly but rather prefer to gather in groups. This phenomenon is not caused by the BS rate only, but also by cohesive–adhesive competition between carbon and nickel atoms.

Soil contamination has become a major problem because of the large amounts of manmade pollutants and chemicals that have been put into the environment. This study aims to determine the growth rate of Pseudomonas putida to treat soil that has been contaminated with pure biodiesel, B100. The effectiveness on bioremediation have been conducted by examined several physico-chemical tests for biodiesel-contaminated soil before and after seeding with Pseudomonas putida. The physico-chemical tests involved were pH, nitrogen, phosphorus, sulfate and organic carbon. The experimental results show that after 20 days pure culture Pseudomonas putida able to remove approximately 69 % of nitrogen, 27 % of sulphate, however, no removal for phosphate and organic carbon. The results indicated that the application of this bacterium is suitable for the degradation of nitrogen and sulfate in biodiesel-contaminated soil. The Pseudomonas putida growth has slightly increased from Day 2 (3.0 × 107 CFU/ml) to Day 8 (4.1 × 107 CFU/ml). After Day 8, the amount of Pseudomonas putida slightly starts to deplete until Day 20 (4 × 106 CFU/ml). The available nutrient in the sample is low once the bacterium has used them as source of carbon and energy before Day 8. Overall, this study proved that Pseudomonas putida is the effective microorganism and potentially exploit as useful oil-soil biodegradable agent.

We modeled a tunneling current in a p-n junction based on armchair graphene nanoribbons (AGNRs) by using an Airy function approach (AFA) and a transfer matrix method (TMM). We used β-type AGNRs, in which its band gap energy and electron effective mass depends on its width as given by the extended Huckel theory. It was shown that the tunneling currents evaluated by employing the AFA are the same as those obtained under the TMM. Moreover, the calculated tunneling current was proportional to the voltage bias and inversely with temperature.

In this work, we studied electron transmittance and tunneling current in isotropic n+Poly-Si/HfSiOxN/Trap/SiO2/p-Si capacitors by including the coupling effect between transverse and longitudinal kinetic energies represented by an electron velocity in the gate. It was used an HfSiOxN/SiO2 dual ultrathin layer as the gate oxide in an isotropic n+poly-Si/oxide/Si capacitor to replace SiO2. The charge trapping formed at the HfSiOxN/SiO2 interface is the main problem in using HfSiOxN because it can affect the performance of the device. Additionally, the tunneling current in metal-oxide-semiconductor (MOS) capacitor with high-κ dielectric stacks is almost zero at low bias voltage regime without considering the effect of trap. Hence, it is necessary to develop a model of tunneling current with considering the trap effect at the HfSiOxN/SiO2 interface. The transmittance was numerically calculated by employing a transfer matrix method. The transmittance was then applied to calculate tunneling currents in the stru...

Quantum effects have been incorporated in the analytic potential model for cylindrical surrounding-gate or gate-all-around metal oxide semiconductor field effect transistors (MOSFETs). By extracting some constants parameter from the self-consistent Schrodinger and Poisson equations, two physical parameters, threshold voltage shift and inversion layer centroid, are expressed as closed form function of device radius and charge density. The quantum version of inversion charge density is obtained by incorporating of those parameters into the classical procedure as modifications for gate work function and inversion layer capacitance. The model represented here has been able to reproduce simulation data obtained from self-consistent calculation. The calculated results show that the model fits well with the self-consistent calculation.

Melanomas on the foot are difficult to differentiate from diabetic foot ulcers (DFU). In particular, acral lentiginous and amelanotic melanomas have a high chance of being misdiagnosed. We present two patients with diabetes mellitus and malignant melanomas of the foot initially diagnosed as DFU. Both cases were treated with wide excision amputation and local dissection, without adjuvant chemotherapy or radiotherapy. Both patients remain disease-free up to the last follow-up visit. It is important to maintain a high index of suspicion and a skin biopsy should be done in any DFU with atypical features.

In this paper, we have developed a model of the tunneling currents through a high-k dielectric stack in MOS capacitors with anisotropic masses. The transmittance was numerically calculated by employing a transfer matrix method and including longitudinal-transverse kinetic energy coupling which is represented by an electron phase velocity in the gate. The transmittance was then applied to calculate tunneling currents in TiN/HfSiO x N/SiO 2 /p-Si MOS capacitors. The calculated results show that as the gate electron velocity increases, the transmittance decreases and therefore the tunneling current reduces. The tunneling current becomes lower as the effective oxide thickness (EOT) of HfSiO x N layer increases. When the incident electron passed through the barriers in the normal incident to the interface, the electron tunneling process becomes easier. It was also shown that the tunneling current was independent of the substrate orientation. Moreover, the model could be used in designing high speed MOS devices with low tunneling currents. DOI: http://dx.doi.org/10.11591/telkomnika.v10i3.607

Electron transmittance and tunneling current through high-k dielectric gate stacks of metal-oxide-semiconductor (MOS) capacitors have been calculated by including transverse-longitudinal kinetic energy coupling, which is represented by a gate electron phase velocity, and anisotropic masses. Metal gate/HfSiOxN/SiO2/p-Si(100) structures with applying a negative bias voltage to the gate is used to discuss the transmittance and tunneling current. In this work, the effect of the work function to the transmittance and tunneling current are considered. It is shown that the transmittance decreases as the work function increases. It is also found that the tunneling current is influenced by the metal work function.

An analytical model of electron transmittance and tunneling current in an anisotropic n+poly‐Si/HfO2/SiO2/Si (100) metal‐oxide‐semiconductor capacitor by including a trap between n+ and SiO2 interfaces has been derived. It considers the coupling of electron transverse and longitudinal motions and uses an Airy‐wavefunction approach. It has been shown that the tunneling current density increases as the trap becomes deeper or wider because many resonant states available in the quantum well.

A model for describing the electron transmittance and tunneling current in anisotropic MOS devices with a high‐k dielectric stack is studied by including the off‐diagonal effective‐mass tensor elements and the effect of coupling between transverse and longitudinal energies. The HfO2/SiO2 dual ultrathin layer is used as the gate oxide in an n+poly‐Si/oxide/Si capacitor. The main problem of using HfO2 is the charge trapping formed at the HfO2/SiO2 interface that can influence the performance of the device. In addition, without taking into account the effect of trap, the tunneling current in the n+‐poly Si/HfO2/SiO2/Si capacitor is almost zero at low bias voltage regime. Therefore, it is important to develop a model taking into account the presence of electron traps at the HfO2/SiO2 interface in the electron transmittance and tunneling current. In this paper, the effects of the electron incident angle and silicon substrate orientation on the transmittance and tunneling current are studied by utilizing the de...

The electron transmittance and tunneling current in n+poly Si/HfO2/SiO2/Si(100) capacitors with an electron trap created at the interface between HfO2 and SiO2 layer have been calculated by using a transfer‐matrix method. The electron motion was considered not only in a longitudinal direction but also in a transversal direction. The trap was modeled as a quantum well. It has been found that as the trap becomes deeper and wider, the transmittance and tunneling current get higher. It has also been found that the quantum well is able to generate a resonant tunneling and this resonant tunneling will result in an oscillatory behavior in the tunneling current.

An electron direct tunneling current model of n+- poly - Si/SiO2/p - Si(100) metal-oxide-semiconductor (MOS) capacitors has been developed by considering a parallel-perpendicular kinetic energy coupling, which is represented by the gate electron phase velocity, and anisotropic masses under a parabolic E-k dispersion relationship. The electron effective mass in the oxide and the electron phase velocity in the n+ poly-Si gate are the only two fitting parameters to compare calculated tunneling currents to measured ones. It was obtained that the calculated tunneling currents fit well to the measured ones. The electron effective mass in the oxide layer tends to increase with decreasing the oxide thickness. In addition, the gate electron velocity is a constant of 1x10(5)m/s. Moreover, the theoretical model offers a simple treatment and an accurate result in obtaining the tunneling current.

TiO2 solar cells were fabricated consisting TiO2 layer, TiO2 nanocomposite layers, electrolyte polymer and counter electrode layer. It was found that TiO2 nanocomposite layer that contains metal (Zn) contact could be conductive and make better charge transfer than pure TiO2. Conversion efficiency 1.0% was achieved using TiO2 nanocomposite. It indicates that using of TiO2 nanocomposite is an effective technique for improvement of conversion efficiency.

Electron transmittance and tunneling current through high‐k dielectric gate stacks of metal‐oxide‐semiconductor (MOS) capacitors have been calculated by including an anisotropic mass and a transverse‐longitudinal kinetic energy coupling which is represented by a gate electron phase velocity. TiN/HfSiOxN/SiO2/p‐Si(100) structures with applying a negative bias voltage to the TiN metal gate is used to discuss the transmittance and tunneling current. In this work, the effects of the incident angle of electron and the valley in the anisotropic Si(100) to the transmittance and tunneling current are considered. It is found that the transmittance decreases as the electron gate phase velocity increases. It is also found that the transmittance and tunneling current get the highest at the incident angle of 0°. In addition, the transmittance is insignificantly affected by the valleys in the anisotropic Si(100) substrate.

We introduced a parameter to distinguish how well (the quality) of organization of nanoparticles in self‐organized samples. This parameter measures how far the deviation of real particle positions in the sample with respect to positions of particles forming a perfect lattice of the corresponding packing structure. The perfect lattice was developed by taking the lattice site as the average distance between contacting particles in the sample.

The theoretical collector current model for SiGe-based heterojunction bipolar transistors under parallel–perpendicular kinetic energy coupling and anisotropic masses was validated. Verification was performed by comparison to Monte Carlo (MC) calculations and experimental data obtained from previous publications. Collector current against base-emitter voltage obtained by the present model is comparable to that calculated by the MC method. The measured collector currents as a function of base-collector voltage agreed well with the calculated currents for base-emitter voltages ranging from 0.3 to 0.6 V.

A leakage current in a metal-oxide-semiconductor (MOS) capacitor has been calculated taking into account an in-plane-longitudinal kinetic energy coupling, which is represented by an electron phase velocity in the gate, and anisotropic and isotropic mass approaches. The leakage currents computed under these approaches were fitted to the measured data. It was found that the calculated tunnelling currents fit well to the measured ones. It was also found that the leakage currents evaluated under the isotropic mass approach are identical with that computed under the anisotropic one. Moreover, the calculated current by considering the coupling effect and isotropic mass is able to obtain leakage currents in MOS capacitors with simplicity but with appropriate results.

We have modelled quantum mechanically the drain current in double gated armchair graphene nanoribbon field-effect transistors (AGNR-FETs). The Dirac 'like' equation was used to determine the electron wave functions in the AGNR. The electron transmittance and the drain current were calculated numerically by using a transfer matrix method (TMM). The results showed that the drain current of the AGNR-FET devices increases with the drain and gate voltages. In addition, the threshold voltage of the devices was obtained to be constant at about 0.3 V. Moreover, the drain current increased with decreasing the thickness of insulator. The different temperatures gave the different characteristics of the drain current.

Analytical expressions of electron transmittance and tunneling current in an anisotropic TiNx/HfO2/SiO2/p-Si(100) metal—oxide—semiconductor (MOS) capacitor were derived by considering the coupling of transverse and longitudinal energies of an electron. Exponential and Airy wavefunctions were utilized to obtain the electron transmittance and the electron tunneling current. A transfer matrix method, as a numerical approach, was used as a benchmark to assess the analytical approaches. It was found that there is a similarity in the transmittances calculated among exponential- and Airy-wavefunction approaches and the TMM at low electron energies. However, for high energies, only the transmittance calculated by using the Airy-wavefunction approach is the same as that evaluated by the TMM. It was also found that only the tunneling currents calculated by using the Airy-wavefunction approach are the same as those obtained under the TMM for all range of oxide voltages. Therefore, a better analytical description for the tunneling phenomenon in the MOS capacitor is given by the Airy-wavefunction approach. Moreover, the tunneling current density decreases as the titanium concentration of the TiNx metal gate increases because the electron effective mass of TiNx decreases with increasing nitrogen concentration. In addition, the mass anisotropy cannot be neglected because the tunneling currents obtained under the isotropic and anisotropic masses are very different.

Two different components of tunneling current in the TiN/HfSiOxN/SiO2/p-Si(100) metal-oxide-semiconductor capacitor have been presented. The tunneling currents were calculated by taking into account a longitudinal-transverse kinetic energy coupling. The calculated tunneling currents were compared with that measured ones by employing the electron and hole effective masses and phase velocities as fitting parameters. It has been shown that hole tunneling currents dominate at low voltages whereas at high voltages the tunneling currents are mainly contributed by electrons. It has also been found that the effective mass of hole in the HfSiOxN layer is higher than that of electron. The gate electron and substrate hole velocities are 1×105 m/s independent of the HfSiOxN thickness. In addition, it is speculated that the electron and hole effective masses in the HfSiOxN layer perhaps increase as its thickness decreases.

An analytic model of the stress-induced leakage current in thin gate oxides was developed under the assumptions that traps created in the gate oxide during high field injection of electrons have an exponential distribution in energy and transport of the electrons localized in the traps is due to an activated process of motion from one trap to another. The electric field and temperature dependence of the leakage current in a wide range were explained successfully by the model.