Papers by Keyword: Nanowire

Abstract: Using two highly efficient inhibitors, one for silicon and one for SiO₂ and SiN it is possible by varying the hydrogenperoxide concentration to achieve tuneable formulated chemistry concerning selectivity. So, the same formulation can be used for the selective etching of SiGe25 vs. Si like for GAA applications as well as for the selective etching of SiGe40 vs. SiGe20 like for CFET applications.

Abstract: SiC gate-all-around (GAA) nanowire (NW) MOSFET is one of the most promising device architectures for the next generation of SiC power MOSFETs. This work reveals the great application potential of vertical SiC GAA NW power MOSFETs via TCAD simulation. The investigated devices show higher channel electron mobility (µ_ch) and larger channel carrier density (n_ch) compared to the conventional SiC power MOSFET. Scaling down of NW diameter (D_NW) is beneficial in terms of both, lowering channel resistance (R_ch) via improving n_ch and, increasing breakdown voltage (V_b) by modifying electric field distribution. Low specific-on resistance (R_on,sp) of about 0.68 mΩ∙cm² for 1 kV SiC MOSFET is shown as possible. However, scaling down the D_NW below 100 nm causes an undesirable increase in R_on,sp due to the unscalable device area which is limited by the vertical gate wrapping stacks. The study on device scaling where the NW diameter (D_NW) varies from 500 nm to 25 nm provides valuable design considerations for the device's performance. Finally, a top-down process has been developed for the device fabrication. Vertical SiC NWs with an aspect ratio of 10 are formed by an optimized micro-trench free dry etching process.

Abstract: The magnetic and thermal properties of a ferrimagnetic mixed spin-1 and spin-2 cubic Ising nanowire are studied by using the Monte Carlo simulation. The influences of the nearest (J_AB) and next-nearest neighbor (J_A and J_B) exchange interactions and the single-ion anisotropies (D_A and D_B) on the critical and compensation temperatures are illustrated. Moreover, the phase diagrams on the (temperature, anisotropy) plane are plotted for several values of J_A/|J_AB|. The system shows very rich and interesting behaviors, namely first and second order phase transitions, tricritical points and compensation phenomenon. Finally, the dependence of hysteresis loops on the anisotropies, the exchange interactions and the temperature is also investigated.

Abstract: In this work, we study theoretically and analytically the electronic transport through a nanowire structure composed of a finite cylindrical quantum wire (CQWR) based on barrier AlGaAs semiconductor, sandwiched between two semi-infinite cylindrical GaAs quantum well wires (CQWWRs). Using the Green function approach to determine the electronic structure of this artificial nanostructure, which is analyzed as a function of the geometrical and physical parameters of nanowires structure. The results show the eigen states (confined states), when they interact with the incoming electronic waves from the first semi-infinite cylindrical GaAs quantum well wire. The decrease of the radius of the system leads to the energy quantization of the electrons and the electronic states move towards high energies until a critical radius R_c=20Å below which no electronic state can exist. In addition, we found that the electronic energy levels of the finite cylindrical quantum wire depend on the mole fraction of aluminum and the ratio between the radius of the cylindrical nanowires and the thickness of the barrier, which are the most important parameters in the optimization of the cylindrical quantum wires nanostructure.Keywords: Cylindrical Quantum Wire, Nanowire, Electronic States, Green Function

Abstract: Integration of low bandgap antimonide based nanowires on Si substrate has been attracting huge attention for opto-electronic applications. In this work we demonstrated InAs/InSb and InAs/GaSb heterostructure nanowires on Si substrate by metal organic chemical vapor deposition. We grew high quality axial InSb heterostructure segment on InAs stem by self-catalyzed growth technique, which paves a way to tune the crystal structure of InSb. In case of InAs-GaSb core-shell architecture, GaSb crystal quality highly depends on InAs core. We successfully demonstrated basic electrical characteristics of InAs-GaSb core-shell nanowire which exhibits negative differential resistance at 0.8 V and peak-to-valley current ratio of 3.84.

Abstract: This paper addresses challenges and solutions of replacement metal gate of gate-all-around nanosheet devices. The unit process and integration solutions for the metal gate patterning as well as interface dipole patterning to offer multiple threshold voltage have been developed. The challenges of long channel device integration are also discussed.

Abstract: 3 formulated etchants were prepared and their etch rates were measured using blanket wafers in order to confirm that the etching reactions on Si_1-XGe_X and Si are controllable. Si_1-XGe_X selective etching with those formulations was also verified using the wafers which had Si_1-XGe_X and Si multi-stacked structures. Cross-sectional transmission electron microscope (TEM) images suggested that the formulations were usable for Si_1-XGe_X selective etching processes.

Abstract: Large-scale stannous oxide (SnO) nanowires were synthesized via a template and catalyst-free thermal oxidation process. After annealing Sn nanowires embedded AAO template in atmosphere, we observed a large scale of SnO nanowires. SnO nanowires were first prepared via the electrochemical deposition and an oxidization method based on an AAO template. The preparation of SnO nanowires use aluminum sheet (purity 99.999%) and then two-step anodization procedure to obtain raw alumina mold. Finally, transparent alumina mold (AAO template) were obtained by the reaming, soaking with phosphoric acid for 20 minutes and a stripping process. We get a pore size of < 20 nm transparent alumina mold. In order to electroplating needs, we produce platinum film on the bottom surface of AAO template by using sputtering method as the electrode of electroplating deposition. The structure was characterized by X-ray diffraction (XRD). High resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) with x-ray energy dispersive spectrometer (EDS) was used to observe the morphology. The EDS spectrum showed that components of the materials are Sn and O. FE-SEM results show the synthesized SnO nanowires to have an approximate length of ~ 10 - 20 μm with a highly aspect ratio > 500. SnO nanowires with an Sn/O atomic ratio of ~ 1 : 1 were observed from EDS. The crystal structure of SnO nanowires showed that all the peaks within the spectra can be indexed to SnO with a tetragonal structure. This studies may lead to the use of the 1D structure nanowires into electronic nanodevices and/or sensors, thus leading to nanobased functional structures.

Abstract: This paper presents a simple approach to selectively synthesize the ZnO nanowires between interdigitated electrodes by integrating the hydrothermal method with the photolithography process. The printed circuit board (PCB) was adopted as the substrate. Interdigitated electrodes were fabricated by etching the copper foil of PCB. Then, both the positive and negative photoresists were used to control the growth of nanowires through lift-off concept. No costly materials and expensive apparatuses are required. Biotin–streptavidin reaction was used as an example to examine this proposed device. When histidine-tagged biotin was added and the reaction of biotin–streptavidin was completed, the distinguishable I-V curves were detected, respectively. The experimental results reveal that this proposed device is sensitive.

Abstract: The mechanical properties and deformation mechanism of nickel nanowire of dimension 100 Å (x-axis) × 1000 Å (y-axis) × 100 Å (z-axis) containing a single linear surface defect is studied at different temperatures using molecular dynamics simulations. The defect is created by deleting a row of atoms on the surface and is inclined at 25° to the loading axis. The tensile test is carried out at 0.01 K, 10 K, 100 K and 300 K temperature and 10⁸ s^-1strain rate. To determine the effect of temperature on the stress-strain curves, fracture and failure mechanism, a thorough investigation has taken place. Maximum strength of 21.26 GPa is observed for NW deformed at 0.01 K temperature and the strength decreased with increase in temperature. Through slip lines, the deformation relief pattern taken place by developing the extrusion areas along with intrusion over the surface defect area in all NWs deformed at respective temperatures. Further it is observed that fracture strains decrease with increase in temperature. After yielding, stacking faults associated with dislocations are generated by slip on all four {111} planes. Different type of dislocations with both intrinsic and extrinsic stacking faults are noticed. Out of all dislocation densities, Shockley partial dislocation densities has recorded a maximum value.