Impurity Diffusion and Space Charge Layers in "Fused-Impurity"p−nJunctions

Abstract

Fused-impurity $p-n$ junctions have properties which depend upon alloying and diffusion of impurities. The inverse-voltage space charge distribution in such junctions is found to be such that nearly all the applied potential drop occurs within the base material. The barrier capacitance varies inversely as the square root of the applied voltage as expected for an abrupt transition junction. However, the diffusion of only 2×${10}^{12}$ acceptor atoms per ${\mathrm{cm}}^2$ into $n$-type germanium is found sufficient to include the space charge layer (which includes the region of maximum dielectric stress) entirely below the diffused surface, in the relatively undisturbed base material.