PROBLEMS RELATED TO THE AVALANCHE AND SECONDARY BREAKDOWN OF SILICON P-N-JUNCTION

The paper provides an analysis of some still unsolved problems related to avalanche and secondary breakdown. An evaluation is given of four models of energy accumulation, necessary for impact ionization: Wolfs diffusion model, Shockley's model of 'lucky' electrons, Ridely's model of 'lucky-drift' and Gribnikov's model of 'light' electrons. It is sh own that impact ionization is mainly realized in conformity with the m odel of 'light' charge carriers. It is indicated that the bright avala nche breakdown channels, called microplasmas, are encircled by a weakl y shining ring-shaped cloud. Apparently this cloud is caused by the'li ght' charge carriers. As the p-n junction is heated under the influenc e of a high avalanche breakdown current and reaches a certain temperat ure, the luminous clouds expand and by force of the magnetic pinch cre ated by the current itself tend towards the centre, where they meet an d assume the form of a ring. Then the weakly shining cloud (pre-mesopl asma) contracts rapidly and bright circular mesoplasma lights up (seco ndary breakdown appears) which moves in the direction of higher temper ature and higher voltage until it localizes at a large defect or conta ct. A model is proposed according to which pre-mesoplasma and mesoplas ma is a Row of 'light' charge carriers. This model allows us to explai n many peculiarities of pre-mesoplasma and mesoplasma. Copyright (C) 1 997 Elsevier Science Ltd.