Threshold voltage and space charge in organic transistors

We investigate rubrene single-crystal field-effect transistors, whose stability and reproducibility are sufficient to measure systematically the shift in threshold voltage as a function of channel length and source-drain voltage. The shift is due to space-charge transferred from the contacts, and can be modeled quantitatively without free fitting parameters, using Poisson's equation, and by assuming that the density of states in rubrene is that of a conventional inorganic semiconductor. Our results demonstrate the consistency, at the quantitative level, of a variety of recent experiments on rubrene crystals, and show how the use of FET measurements can enable the determination of microscopic parameters (e.g., the effective mass of charge carriers).Comment: 4 pages, 4 figure

Labour Supply and Commuting

A new paradigm for transport economists has been established: revenues of a welfare-maximising road tax should be employed to reduce the level of a distortionary income tax. An essential modelling assumption to reach this conclusion is that the number of workdays is optimally chosen, whereas daily workhours are fixed, implying that given a road tax, workers may only reduce their commuting costs by reducing total labour supply. However, a labour supply model which also allows for optimally chosen daily hours implies that commuting costs increase daily hours, whereas the effect on total labour supply is ambiguous. This paper addresses this issue empirically by analysing the relationship between labour supply patterns and commuting distance using the socio-economic panel data for Germany between 1997 and 2007. Endogeneity of commuting distance is accounted for by using employer-induced changes in commuting distance. In line with the theoretical model developed, we find that commuting distance has a positive effect on daily hours. Our analysis does not find a negative effect of commuting distance on total labour supply, suggesting that a reduction in the income tax, as advocated in the literature, may not be necessary.labour supply, congestion tax, commuting cost

Labour Supply and Commuting

We examine the effect of commuting on labour supply patterns. A labour supply model is introduced which shows that commuting distance increases daily workhours, whereas the effect on total labour supply is ambiguous. This paper addresses these issues empirically using the socio-economic panel data for Germany between 1997 and 2007. Endogeneity of commuting distance is accounted for by using employer-induced changes in commuting distance. In line with the theoretical model developed, we find that commuting distance has a slight positive effect on daily workhours. Further, we find a similar effect on weekly labour supply, but no effect on workdays. Distinguishing between males and females, it appears that the effects on labour supply are mainly through the behaviour of females, but the effects for females are still small.Commuting, congestion tax, labour supply

Quantum groups, non-commutative Lorentzian spacetimes and curved momentum spaces

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