Investigation of tunneling effects modeling in degenerate semiconductors

Tunneling effect is an important process in degenerate semiconductors,especially when the electrical field in space charge regions is very strong (upper than 109 v.cm-1) and doping is higher (upper than 1019 cm-3). this paper provides a detailed description of tunneling mechanisms in a multi-junction structure. it takes into account the band-to-band tunneling effect and the traps-assisted tunneling process through discrete states located in the bandgap. the numerical algorithm is based on a one-dimensional steady state drift diffusion model and uses the fermi-dirac statistics to describe carrier's transport in semiconductors. the use of this distribution leads to an integral calculation which cannot be evaluated analytically and needs special numerical methods. our model employs also a generalized scharfetter-gummel discretization scheme,which is consistent with both equilibrium and non-equilibrium cases. numerical tests have been carried out on a multi-junction structure with different levels of doping including layers with degenerate and non-degenerate semiconductors. different parameters and electrical characterizations have been simulated to examine the contribution of these effects in the performance of the structure. it is shown that extended scharfetter-gummel scheme is stable convergent. on the other hand,adding tunneling effect shows the predicted peak and valley in the i-v curve. © 2017,university of mohammed premier oujda morocco.