Electrical characterization of high-k gate dielectrics for advanced CMOS gate stacks

The oxide/substrate interface quality and the dielectric quality of metal oxide semiconductor (MOS) gate stack structures are critical to future CMOS technology. As SiO2 was replaced by the high-k dielectric to further equivalent oxide thickness (EOT), high mobility substrates like Ge have attracted increasing in replacing Si substrate to further enhance devices performance. Precise control of the interface between high-k and the semiconductor substrate is the key of the high performance of future transistor. In this study, traditional electrical characterization methods are used on these novel MOS devices, prepared by advanced atomic layer deposition (ALD) process and with pre and post treatment by plasma generated by slot plane antenna (SPA). MOS capacitors with a TiN metal gate/3 nm HfAlO/0.5 nm SiO2/Si stacks were fabricated by different Al concentration, and different post deposition treatments. A simple approach is incorporated to correct the error, introduced by the series resistance (Rs) associated with the substrate and metal contact. The interface state density (Dit), calculated by conductance method, suggests that Dit is dependent on the crystalline structure of hafnium aluminum oxide film. The amorphous structure has the lowest Dit whereas crystallized HfO2 has the highest Dit. Subsequently, the dry and wet processed interface layers for three different p type Ge/ALD 1nm-Al2O3/ALD 3.5nm-ZrO2/ALD TiN gate stacks are studied at low temperatures by capacitance-voltage (CV),conductance-voltage (GV) measurement and deep level transient spectroscopy (DLTS). Prior to high-k deposition, the interface is treated by three different approaches (i) simple chemical oxidation (Chemox); (ii) chemical oxide removal (COR) followed by 1 nm oxide by slot-plane-antenna (SPA) plasma (COR&SPAOx); and (iii) COR followed by vapor O3 treatment (COR&O3). Room temperature measurement indicates that superior results are observed for slot-plane-plasma-oxidation processed samples. The reliability of TiN/ZrO2/Al2O3/p-Ge gate stacks is studied by time dependent dielectric breakdown (TDDB). High-k dielectric is subjected to the different slot plane antenna oxidation (SPAO) processes, namely, (i) before high-k ALD (Atomic Layer Deposition), (ii) between high-k ALD, and (iii) after high-k ALD. High-k layer and interface states are improved due to the formation of GeO2 by SPAO when SPAO is processed after high-k. GeO2 at the interface can be degraded easily by substrate electron injection. When SPAO is processed between high-k layers, a better immunity of interface to degradation was observed under stress. To further evaluate the high-k dielectrics and how EOT impacts on noise mechanism time zero 1/f noise is characterized on thick and thin oxide FinFET transistors, respectively. The extracted noise models suggest that as a function of temperatures and bias conditions the flicker noise mechanism tends to be carrier number fluctuation model (McWhorter model). Furthermore, the noise mechanism tends to be mobility fluctuation model (Hooge model) when EOT reduces

Differential fates of Emiliania huxleyi-derived fatty acids and alkenones in coastal marine sediments: Effects of the benthic crustacean Palaemonetes pugio

In order to examine how benthic crustaceans affect the fates of phytoplankton-derived lipid biomarkers (fatty acids and alkenones) in coastal marine sediments, we incubated Emiliania huxleyi cells in microcosms (pre-sieved sediment cores with and without the grass shrimp Palaemonetes pugio ) over six weeks. Crustacean, transport of surface sediments, and distributions of algal lipids were followed during incubations. Crustacean activities enhanced degradation of algal fatty acids (2–4× faster) but had a small impact on algal alkenone degradation (\u3c1.4×) compared to the controls. During the first few days of incubations, alkenone concentrations were enriched while algal fatty acid concentrations were depleted in suspended particles in the overlying water of cores, indicating that P. pugio selectively grazed algal material from sediments and preferentially assimilated fatty acids over alkenones through digestion. Unlike algal fatty acids, alkenones were degraded primarily by microbial processes rather than by crustacean grazing. A substantial fraction (20–30%) of algal lipids was moved downward to the subsurface of sediments by P. pugio but algal fatty acids were more rapidly (3–6×) degraded than alkenones. In the presence of P. pugio, fatty acids bound in cell membrane and intracellular storage components degraded similarly, indicating that the crustacean activities minimized the effects of structural associations on fatty acid decomposition. Furthermore, there was no preferential degradation of 37:3 and 37:2 alkenones in both crustacean and control cores, suggesting that the U37k\u27 index (a paleotemperature indicator) was not significantly altered by P. pugio\u27s grazing or microbial decomposition

Molecular docking via quantum approximate optimization algorithm

Molecular docking plays a pivotal role in drug discovery and precision medicine, enabling us to understand protein functions and advance novel therapeutics. Here, we introduce a potential alternative solution to this problem, the digitized-counterdiabatic quantum approximate optimization algorithm (DC-QAOA), which utilizes counterdiabatic driving and QAOA on a quantum computer. Our method was applied to analyze diverse biological systems, including the SARS-CoV-2 Mpro complex with PM-2-020B, the DPP-4 complex with piperidine fused imidazopyridine 34, and the HIV-1 gp120 complex with JP-III-048. The DC-QAOA exhibits superior performance, providing more accurate and biologically relevant docking results, especially for larger molecular docking problems. Moreover, QAOA-based algorithms demonstrate enhanced hardware compatibility in the noisy intermediate-scale quantum era, indicating their potential for efficient implementation under practical docking scenarios. Our findings underscore quantum computing's potential in drug discovery and offer valuable insights for optimizing protein-ligand docking processes.Comment: 10 pages, 5 figures, All comments are welcom

Ballistic Thermal Rectification in Asymmetric Three-Terminal Mesoscopic Dielectric Systems

By coupling the asymmetric three-terminal mesoscopic dielectric system with a temperature probe, at low temperature, the ballistic heat flux flow through the other two asymmetric terminals in the nonlinear response regime is studied based on the Landauer formulation of transport theory. The thermal rectification is attained at the quantum regime. It is a purely quantum effect and is determined by the dependence of the ratio $\tau_{RC}(\omega)/\tau_{RL}(\omega)$ on $\omega$, the phonon's frequency. Where $\tau_{RC}(\omega)$ and $\tau_{RL}(\omega)$ are respectively the transmission coefficients from two asymmetric terminals to the temperature probe, which are determined by the inelastic scattering of ballistic phonons in the temperature probe. Our results are confirmed by extensive numerical simulations.Comment: 10 pages, 4 figure