SINGULAR PERTURBATION ANALYSIS FOR MULTID IMENSIONAL SEMICONDUCTORS

The drift-diffusion equations can be studied in the framework of singu lar perturbation analysis as a small parameter characterizing the devi ce, goes to zero. A formal asymptotic expansion, which include interna l (and eventually boundary) layer terms can be derived by standard tec hniques of asymptotic analysis. We present in Note L2 estimates for th e difference between the solutions of the full system and the first te rm of the expansion which are valid for multi-dimensional devices clos e to equilibrium.