Characterization of space-charge properties of a linearly graded p-n junction by an approximate "Regional" analysis method

A new approximate analysis of the linearly graded p-n junction is developed which gives solutions for the space-charged density and mobile carrier densities as distributions within a finite space-charge width. The results obtained are in good agreement with the true unbounded solution of Poisson's equation and represent a considerable improvement in space-charge modeling over previous approaches to approximate "regional" analysis. The solution process is implemented numerically as a computer algorithm in terms of either the total junction space charge or the applied voltage as a parameter; it is appropriate for application in the analysis of devices by the regional method where modeling of space-charge and mobile carrier distributions is required. Results are presented for the space-charge density distributions of linearly graded junctions; also for the space-charge capacitance and total junction capacitance including the high forward bias region.