This paper considers a deterministic Susceptible-Infected-Susceptible (SIS) metapopulation model for the spread of a disease in a strongly connected network, where each node represents a large population. Individuals can travel between the nodes (populations). We derive a necessary and sufficient condition for the healthy equilibrium to be the unique equilibrium of the system, and then in fact it is asymptotically stable for all initial conditions (a sufficient condition for exponential stability is also given). If the condition is not satisfied, then there additionally exists a unique endemic equilibrium which is exponentially stable for all nonzero initial conditions. We then consider time-delay in the travel between nodes, and further investigate the role of the mobility rate that governs the flow of individuals between nodes in determining the convergence properties. We find that sometimes, increasing mobility helps the system converge to the healthy equilibrium.

High quality passivating contacts can be realized by using the combination of a thin interfacial oxide (SiO_x) and doped polysilicon (polySi). Recombination losses are minimized by providing very good passivation between the thin hydrogenated oxide and the cSi, a high field effect by the highly doped polySi [1-2], combined with the low level penetration of dopants in the wafer [2-3]. To realize this low level in-diffusion of dopants, several interacting options are evaluated in this work: the quality of the thin oxide layer (growth method), combined with a diffusion blocking method (nitridation), doping concentration levels in the polySi and temperature of diffusion. It is shown that for Phosphorus (P)-doped polySi, in-diffusion can be reduced by adding an i-layer in between the oxide and the highly doped polySi, lowering the overall doping level in the system slightly. For Boron (B)-doped polySi, in-diffusion can be blocked by nitridation of the SiO2 layer.