Two interacting diffusing particles on low-dimensional discrete structures

In this paper we study the motion of two particles diffusing on low-dimensional discrete structures in presence of a hard-core repulsive interaction. We show that the problem can be mapped in two decoupled problems of single particles diffusing on different graphs by a transformation we call 'diffusion graph transform'. This technique is applied to study two specific cases: the narrow comb and the ladder lattice. We focus on the determination of the long time probabilities for the contact between particles and their reciprocal crossing. We also obtain the mean square dispersion of the particles in the case of the narrow comb lattice. The case of a sticking potential and of 'vicious' particles are discussed.Comment: 9 pages, 6 postscript figures, to appear in 'Journal of Physics A',-January 200

A physical large-signal model for GaN HEMTs including self-heating and trap-related dispersion

We show results of a self-consistent large-signal electro-thermal GaN HEMT model that includes trap related and self-heating dispersion effects. Both self-heating and trap dynamics are treated with a strictly physical approach that makes it easier to link the model parameter with the physical HEMT structure and material characteristics. The model, implemented in ADS, is applied to measured DC data taken at ambient temperatures between 200 K and 400 K, with excellent results. Several examples are given of dynamic HEMT simulation, showing the co-existence and the interaction of temperature- and trap related dispersive effects