Influence of deep traps on the measurement of free-carrier distributions in semiconductors by junction capacitance techniques

Abstract

A generalized model is developed for the electronic behavior of deep traps in a p-n-junction depletion region. The depletion region is shown to consist of two parts: (i) a space-charge region which is totally depleted of free carriers and (ii) a transition region which is only partially depleted. The influence of this junction structure on free-carrier profiling measurements is considered in detail for donor and acceptor traps with both homogeneous and inhomogeneous spatial distributions. Experimental observations of deep-trap distributions produced by proton bombardment of n-type silicon are analyzed within the framework of the model. Implications of the model in the measurement of junction capacitance transients and photocapacitance are considered in Appendices A-C.