Periodic Phenomena in Photosynthesis

Abstract

It has been shown that the low voltage gate current in ultrathin oxide metal-oxide-semiconductor devices is very sensitive to electrical stresses. Therefore, it can be used as a reliability monitor when the oxide thickness becomes too small for traditional electrical measurements to be used. In this work, we present a study on n-MOSCAP devices at negative gate bias in the direct tunneling (DT) regime. If the low voltage stress-induced leakage current (LVSILC) depends strongly on the low sense voltages, it also depends strongly on the stress voltage magnitude. We show that two LVSILC peaks appear as a function of the sense voltage in the LVSILC region and that their magnitude, one compared to the other, depends strongly on the stress voltage magnitude. One is larger than the other at low stress voltage and smaller at high stress voltage. From our experimental results, different conduction mechanisms are analyzed. To explain LVSILC variations, we propose a model of the conduction through the ultrathin gate oxide based on two distinctly different trap-assisted tunneling mechanisms: inelastic of gate electron (INE) and trap-assisted electron (ETAT). P g = J /J 0 Q inj , where J is the SILC and is equal to (J − J 0 ) (J 0 and J are the gate current before and after stress, respectively) and Q inj is the injected charge. However, some authors [3] have addressed the LVSILC in terms of J alone, by both characterization, analysis of stress dependence and numerical simulation. They think that the relevance of the LVSILC is simply a consequence of the suppression of direct tunneling current (i.e., virgin) in the voltage range. They propose an alternative interpretation based on the recombination and trap-assisted tunneling (RTAT) model [4]. In this work, we study the relative increase of the gate current, normalized SILC or J /J 0 , to compare and analyze our results with those obtained by various authors using this method.The gate oxide lifetime is undeniably a crucial issue for thinner oxides (t ox 2 nm) [5]. Oxide reliability is characterized by the charge or the time to breakdown at the operating voltage. These quantities are reached by extrapolation from oxide lifetime data obtained under

Entropy production in oscillatory processes during photosynthesis

“…performed on plants, research on the carbon cycle, and kinetic modelling. 18,[31][32][33][34][35] Several experimental methods, such as isotopic gas exchange and electrochemical and fluorescence techniques, [36][37][38][39] have been developed to study the interaction between energy and matter at a molecular level with the highest precision possible, by determining the parameters involved in the regulation and dynamics of the photosynthetic process. Using these methods, scientists have produced a series of hypotheses regarding the destabilizing processes that induce oscillations, such as a decompensation between the ATP/NADPH flow in the Calvin cycle, 40 a competitive kinetic inhibition between kinases for the ATP in the Calvin cycle 41 and the autocatalytic activity of fructose 2,6-biphosphate during the synthesis of sugars, 42,43 among others.…”