Avalanche Effects in Silicon <i>p—n</i> Junctions. II. Structurally Perfect Junctions

Abstract

The fabrication of a planar guard ring diode which exhibits uniform microplasma-free breakdown is described. Discrepancies are discussed between the behavior of these junctions and those reported by Batdorf et al. and Chynoweth, including results showing extremely hard V-I characteristics associated with uniform avalanche breakdown. Experimental evidence is presented which confirms Shockley's theory in which the breakdown behavior is predicted from the Poisson distribution of impurities within the space-charge layer. The photomultiplication technique as described in Paper I is applied to uniform p—n junctions. The linearity of 1/M vs V, as predicted by theory, was verified for values of M between 1.6 and 500. For higher values, the multiplication curves deviate from a straight line. In this higher range they are in good agreement with the pulse-multiplication model developed in Paper I. Light emission patterns from these junctions are shown and a correlation between these patterns and crystal properties is discussed. The effects of resistivity striations in the silicon single crystals is shown to have a strong effect on breakdown areas and no effects of dislocations and oxygen on uniformity are found. From capacity and multiplication measurements a value for the breakdown field of EB=445±25 kV/cm was obtained for a 32-V junction.