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For improving self-heating effect (SHE) in Ge vertically stacked gate-all-around (GAA) nanowire (NW) p-type metal-oxide-semiconductor field-effect transistor (pMOSFET), aluminum oxide (Al2O3, alumina) is utilized for gate dielectric layer. From the high thermal conductivity of Al2O3, SHE is significantly improved. In order to validate the proposed device structure, technology computer-aided design simulation is performed through Synopsys Sentaurus three-dimensional tool. As a result, when Al2O3 is incorporated in Ge vertically stacked GAA NW pMOSFET, SHE can be remarkably improved from 534 to 419 K. In addition, the method of simultaneously accomplishing improvement of SHE and low gate leakage current (I gate) have been specifically investigated and proposed with numerous simulation data.

In this study, a tunnel field-effect transistor (FET) with source-side inner doping and a drain-side spacer is proposed to obtain high current drivability and reduced gate-to-drain capacitance, simultaneously. The effects of the inner doping region (regioninner) are investigated with various lengths (L ID) and concentrations (N ID). As the N ID increases, the more source-to-regioninner tunneling is added to conventional source-to-channel tunneling and thus the total tunneling current is enhanced. Moreover, with a wider L ID, the on-current is reduced by the wider source-to-regioninner tunneling width and the source-to-regioninner tunneling is generated at a lower gate voltage by the L ID-induced limitation of energy band bending. Also, the impact of the inner spacer is evaluated with various inner spacer lengths (L IS). By introducing the inner spacer, the gate-to-drain capacitance can be significantly reduced. Consequently, the proposed tunnel FET has a reduced gate-to-drain capacitance as well as an increased tunneling current, which leads an improvement in switching delay.

In this study, the body-bias effects on negative capacitance FET (NCFET) are analyzed using technology computer-aided design (TCAD) device simulation with drift-diffusion model and Landau-Khalatnikov. To understand the physical origin the effects, electrical characteristics are evaluated with various ferroelectric (FE) layer thickness for NCFET as compared to the conventional MOSFET. With thicker FE layer, the total capacitance (C Total) becomes larger, while MOS capacitance (C MOS) is sustained, leading to voltage amplification because the difference between C FE and C MOS gets smaller. It gives the strong gate controllability and less sensitivity for threshold voltage (V TH) according to body-bias variations unlike the conventional MOSFET. Moreover, it is confirmed that the surface band-bending at the interface of NCFET is rarely changed with changing body-bias from 0V to −3V.

The circular mitochondrial genome of the mud spiny lobster, Panulirus polyphagus was determined by next-generation sequencing (NGS) platform. The mitochondrial genome of P. polyphagus was 15,707 bp in length, which comprised 13 protein-coding genes, 22 tRNAs, two ribosomal RNAs (12S and 16S). A non-coding putative control region (739 bp) was located between 12S ribosomal RNA and tRNA-Ile. Except for COX1, 13 protein-coding genes initiated with the conventional start codon (ATG). The phylogenetic analysis with the mitogenomes in family Palinuridae showed P. polyphagus was clustered together with four congener species forming a clade, and Panulirus versicolor is closest to P. polyphagus.

The effect of sweeping direction on the capacitance–voltage (C–V) behavior of sputtered SiO2/4H-silicon carbide (SiC) metal-oxide semiconductor capacitors was investigated. Nitric oxide post-deposition annealing was conducted for the sputtered SiO2 on 4H-SiC. The sweeping direction of the measurement changed the C–V behavior and effective oxide charge density (Q eff) because of trapped electrons at the accumulation and detrapped electrons at the depletion. The nitrogen atoms near interface between SiO2 and 4H-SiC as a result of nitric oxide post-deposition annealing shifted the flat-band voltage in the negative direction. When the C–V was measured from depletion to accumulation, the absolute value of the Q eff after 60 min long annealing, 3.465 × 1010 cm−2 was less than that of the Q eff after 30 min long annealing, −2.912 × 1011 cm−2. The mechanisms of the nitric oxide post-deposition annealing on sputtered SiO2 on 4H-SiC are film densification and nitrogen passivation of the defects.

ZnO and Al-doped ZnO (AZO) were etched in Cl2/CH4/H2/Ar (Cl2-based) and BCl3/CH4/H2/Ar (BCl3-based), inductively coupled plasmas (ICPs) and their etching characteristics were compared by varying the Cl2/(Cl2+CH4) and BCl3/(BCl3+CH4) flow ratios, top electrode power and dc self-bias voltage (Vdc). The etch rates of both ZnO and AZO layers were higher in the Cl2-based chemistry than in the BCl3-based chemistry. The AZO and ZnO etch rates were increased and decreased, respectively, with increasing Cl2 or BCl3 flow ratio. Optical emission measurements of the radical species in the plasma and surface binding states by optical emission spectroscopy (OES) and X-ray photoelectron spectroscopy (XPS), respectively, indicated that, with increasing Cl2 or BCl3 flow ratio; the effective removal of Al in the AZO enhanced the AZO etch rate, whereas the reduced removal of Zn by the Zn(CHx)y products reduced the ZnO etch rate.

Atomic force microscopes (AFM) have been used to measure the strength of adhesion of photoresist patterns which generally collapse during rinsing with water in the development process. We suggest how to measure the collapsing force of the photoresist patterns using an AFM in which a lateral force microscope (LFM) is engaged to determine the tip load at the moment of pattern collapse. The AFM tip was precisely positioned in the space between the patterns in non-contact mode and then scanned in contact mode to the collapse patterns. Loads F for collapse on a scale of nanonewtons (nN) were calculated from the signal of the position-sensitive photodiode. To investigate the variation of the collapsing load for different lengths of patterns, an AFM tip was also used to fabricate patterns with an appropriate length. Our method for measuring the strength of adhesion of photoresist patterns would enable an AFM to be applied to test this property for photoresists.

In this paper, the total drain current (I D) of a tunnel FET (TFET) is decomposed into each current component with different origins to analyze the I D formation mechanisms of the TFET as a function of gate voltage (V GS). Transfer characteristics are firstly extracted with fabricated Silicon channel TFETs (Si TFETs) and silicon germanium channel TFETs (SiGe TFETs) at various temperatures. The subthreshold swings (SS) of both Si TFETs and SiGe TFETs get degraded and the SSs of SiGe TFETs get degraded more as temperature becomes higher. Then, all the I Ds measured at various temperatures are decomposed into each current component through technology computer aided design (TCAD) simulations with a good agreement with experimental data. As a result, it is revealed that Shockley–Read–Hall (SRH) recombination mainly contribute to the I D of a TFET before band to band tunneling (BTBT) occurs. Furthermore, the SS degradation by high temperature is explained successfully by the SRH recombination with electric field dependence.

In order to overcome the small current drivability of a tunneling field-effect transistor (TFET), we have introduced a TFET with the SiGe body and elevated Si drain region. The proposed TFET features large on-current and lower subthreshold swing (SS) compared with the Si TFET. Also, by using elevated Si drain region, it is expected that ambipolar current can be suppressed. Through the technology computer aided design (TCAD) simulation, the characteristics of the proposed TFET have been investigated to confirm its superiority in performance. The proposed TFET structure enables self-aligned doping process and has a strong immunity to short-channel effects compared with the conventional TFET. In addition, we have confirmed that both n- and p-channel characteristics can be simultaneously improved by using the proposed TFET.

A new design of tunneling field-effect transistor (TFET) focusing on the compatibility to the current Si complementary-metal–oxide–semiconductor (CMOS) technology is proposed. In addition to use of the structural components of the state-of-the-art CMOS technologies, such as Σ-shaped embedded SiGe and the replacement gate techniques, two-step sidewall image transfer gate-patterning and channel recess process are adopted to form highly-scaled nanoscale TFET. Process integration scheme and the expected device characteristics are examined on the basis of technology computer-aided design (TCAD) simulation on 14-nm-gate model devices. Tunability of transfer characteristics with doping around tip region, control of short-channel effect with channel recess, and improvement of current drivaility with SiGe composition are studied. Design of the source region is found to be critical in controlling the current drivability of the device and output characteristics.

In this paper, we propose an integrated hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs) gate driver circuit with parallely connected TFTs to resolve problems of the large circuit area and large number of input signals which are founded in the previously reported decoder-type and demultiplexer-type integrated gate drivers. The proposed gate driver can alleviate the demerits of previous gate drivers while maintaining their advantages: reduction of the threshold voltage (V th) shift of the a-Si:H TFTs with an AC-driving structure and provide a stable low-impedance output. The key idea is to construct a novel decoder based on parallely connected TFTs instead of serially connected ones that are very common for decoders. The simulation results show that the rising time and falling time are 1.27 and 1.63 µs respectively with -5 to 30 V output voltage swing which are suitable for high resolution active-matrix displays.

In this work, novel L-shaped tunneling field-effect transistors (TFETs) have been proposed. The proposed L-shaped TFETs feature higher on-current (I on) and lower subthreshold swing (SS) than conventional TFETs. It is because L-shaped TFETs have large cross-sectional area of band-to-band tunneling junction which is perpendicular to the channel direction and their tunneling barrier width (W t) is defined by the length of an intrinsic silicon region. As the devices are based on the Si without any other material, it can be fabricated with well-established Si process technology. In addition, it can moderate some issues come from scaling down and enlarging tunneling area due to its mesa structure. Simulation results have confirmed the superiority of L-shaped TFETs over conventional TFETs. Additionally, the effect of some device parameters on device performance has been investigated for the clear verification of its operation mechanism and the optimization.

A structure of a tunneling field-effect transistor (TFET) featuring an extremely thin body, a double-gated vertical channel, and a source design to maximize the drive current is proposed and optimized on the basis of technology computer-aided design (TCAD) simulation. The field-coupling effect at the double-gated thin-body channel and an engineered tunneling barrier are implemented to maximize the operation current of the device. Weak current drivability under a small drain bias and the directionality of current flow are the expected challenges in building logic circuits with TFETs. A co-integration scheme to build vertical-channel TFETs and metal–oxide–semiconductor field-effect transistors (MOSFETs) is proposed as the solution. A new low-power design using the co-integration scheme is suggested.

The photoresist (PR) thermal flow process is to enhance the resolution of lithography for the patterning of sub-200 nm-diameter contact holes as the required critical dimension (CD) approaches the physical limits of conventional lithography. It is difficult to predict the results of the application of this process, so we develop a new viscous PR flow model, which is verified to be applicable for various PRs from experimental results and is applied to the optimization of the layout design and process parameters. Using the model and simulation, we demonstrate the close agreement between the predicted and obtained results using with vertical scanning electron microscope (VSEM) to study the top corner rounding profile of a PR, and present a method for predicting the effect of changes in the dominant variables such as contact diameter, surrounding bulk density, and temperature. This model is also integrated with a lithography simulator. The layout design and process conditions for patterns with various contact diameters are optimized using our new methodology. The viscous flow model linked to the lithography simulator can be effectively used for predicting the contact patterning process and optimizing the layout, as well as, for analyzing defects.

The patterning of sub-80 nm contact holes and trenches by ArF lithography is very challenging. To solve this problem, several technologies have been proposed, including thermal flow, resolution enhancement of lithography assisted by chemical shrink (RELACS), and shrink assist film for enhanced resolution (SAFIER). In this paper, we compare these processes in order to determine the advantages and disadvantages, and to gain an understanding on their mechanism on the basis of the performances of each process. Thermal flow shows a strong advantage in terms of simplicity, but it shows several disadvantages in terms of layout dependence, mask error enhancement factor (MEEF), and process window. RELACS is proven to be the most reliable, since there is a small shrink amount dependence on layout and temperature, but the limitation of shrink amount is an obstacle. Finally, SAFIER shows strong advantages in low MEEF, wide process window, and enhanced uniformity, with a weakness of the deformation in asymmetric pattern. It is considered that such performances are strongly related to the mechanism of each process, and therefore, the process should be used according to its own performances and mechanism. On the basis of the properties and relationship with the mechanism, the appropriate applications are recommended for each process.

The adsorption of Al on clean and oxidized GaAs(110) surfaces was studied. The characteristics of an oxide surface formed in vacuum and during the chemical etching process of the tip have been investigated using the field desorption (FD) cleaning method and the retarding potential analyzer (RPA) equipped with an argon laser. The results obtained for the FD clean surface and on the oxidized surface are discussed in terms of the RPA threshold and work function change. The oxide films formed at relatively low temperatures on the GaAs(110) surface can easily be desorbed by FD. The intrinsic potential drops across the oxide surface disappear suddenly at a certain field value. This may indicate that the desorbed surface region is composed of a metallic species such as Ga. Changes in work function are observed but there is no change in the threshold values (V th) with deposition of Al on the field-desorbed clean surface. The thick layers of Al on the oxidized surface completely cancel the effect of oxide on V th, which decreases to the value of a metallic clean surface. In addition, the value of V th decreases dramatically to that of a metallic clean surface by absorption of the laser beam on the oxidized surface, whereas only the thermal effect is seen on a metallic clean surface.

The field emitter of the -oriented tungsten was remolded in situ in the field-ion microscope. The remolding was most successful when the electric field of 100 MV/cm was applied to the emitter kept at about 1620 K. The micro-protrusion was formed on the (100) plane if the remolding was carried out in high vacuum (10-8 Torr) and on the (310) plane in ultra-high vacuum (10-10 Torr). The 3 MV electron microscope, as well as the field-ion microscope, were used to estimate the dimensions of the protrusion, which were 10 to 20 A both in height and diameter. The microminiature electron beam with the brightness higher than 1011 A cm-2 rad-2 could be extracted from the remolded emitter.

The coadsorption of thorium and hydrogen on a tungsten surface has been investigated with a field emission microscope (FEM). When the coverage of thorium (θTh)is less than half a monolayer, the work function of the surface decreases with θTh owing to the formation of surface complexes such as WH-Th+ by the adsorption of hydrogen on the Th-covered tungsten surface. The maximum decrease in work function is found to be 0.23 eV at θTh=θH=0.5, when the number of the surface complex, WH-Th+, is largest. When θTh is larger than half a monolayer, the change in the work function (Δ) decreases; it becomes zero at θTh=0.64. Thus, when θH=0.5, the curve for Δ vs. θTh is symmetrical about the point θTh=0.5. When the coverage of hydrogen is larger than 0.5, Δ also decreases owing to the increase in the number of the surface complex, Th+H-, on the coadsorption surface. The sticking probability of hydrogen on a tungsten surface covered with Th is found to be 0.025 to 0.05, half that on a clean tungsten surface. When the coadsorbed surface is heated to 900~1000 K, only the hydrogen is desorbed, with an activation energy of 2.36 eV, comparable to that on a clean tungsten surface.

Field desorption of Pd on W(011),(112) and (111) has been studied to determine the characteristic behavior of adsorbed Pd by field emission and field ion microscopies. The results indicate that the field emission current variations at room temperature in the field desorption process can be classified into three regions: (1) the field desorption of the Pd overlayer atFdes=10–28 V/nm, (2) a region where further field desorption does not occur atFdes=30–37 V/nm and finally, (3) a region where the monolayer of Pd suddenly startes to be desorbed in the critical fieldFdes>∼38 V/nm. Binding energies for the overlayer and the monolayer of Pd were found to be 2.9–4.8 eV and 5.72 eV, respectively. Adsorbed Pd at various stages of the field desorption processes was also observed with a field ion microscopy.