Carrier Lifetimes in Semiconductors with Two Interacting or Two Independent Recombination Levels
Abstract
Carrier recombination under (a) arbitrary steadystate and (b) smallsignal nearequilibrium transient conditions has been studied theoretically for a twointeractinglevel (ITL) model and a twoindependentlevel (IDL) model. Analytic solutions for carrier lifetimes have been obtained and manipulated into a form which facilitates comparison between the two models, as well as comparison between the steadystate and transient lifetimes as predicted by each model. It is shown that under smallsignal steadystate and transient conditions the two interacting levels may be treated, with little loss of accuracy, as two independent levels, provided we describe the effective flaw density at each level by interactinglevel equilibrium statistics. However, under appropriate conditions, the use of either ITL or IDL equilibrium statistics leads to essentially the same lifetimes; the ITL model is then indistinguishable from the IDL model. A comparison of the steadystate and transient lifetimes, whether of two interacting or two independent levels, shows that in certain circumstances the transient lifetime can exceed the sum of the steadystate electron and hole lifetimes, a possibility which does not exist if only one level is present. As a numerical example, the lifetimes in golddoped silicon have been calculated and compared. Some possible applications of this work are proposed.
 Publication:

Physical Review B
 Pub Date:
 January 1970
 DOI:
 10.1103/PhysRevB.1.687
 Bibcode:
 1970PhRvB...1..687C