An interpolated flux scheme for cellular automaton device simulation

Cellular automaton (CA)-based device simulation is one of the most powerful tool to solve Boltzmann transport equation (BTE) of carriers in semiconductor devices. In comparison to Monte Carlo (MC) method which suffers statistical noise problems, cell representation used in CA method realizes noise free analysis of carrier distribution function (DF) both in real and momentum space. However, CA requires more computer resources than MC in typical cases because cell sizes used for both real and momentum space are restricted to be small enough not to cause artificial diffusion (ADF), In this paper, a new scheme for calculation of flux among cells is proposed in which carrier distribution is interpolated between neighbor cells. The suppression of ADF is confirmed through comparisons to other simulation methods in homogenious cases, an n(+)-p diode case and an n(+)-n-n(+) structure case, Consistency to MC analysis is also demonstrated by analyzes of homogenious cases and an n(+)-n-n(+) case and also by a theoretical study. At least speed up of two orders of magnitude can be obtained by introducing the new flux calculation whose accuracy is ensured with much less number of cells than conventional CA methods. Consequently, CA method is drastically improved as a practical tool for semiconductor device modeling from the point of CPU time and accuracy.