Quantitative Fluorescence Determination of Impurities in Compound Semiconductors

Abstract

The electrical behavior of compound semiconductors is governed by the combined effects of the stoichiometry and impurities. The determination of impurity concentration in undoped samples is a largely unsolved problem. This deficiency results from the high purity routinely achieved in these materials, typically 1-20 ppb total impurity concentration, less than the detection limit of the applicable methods, such as SIMS. Progress toward quantitative impurity determination has been achieved by employing electronic Raman scattering, but this method is applicable only to acceptor concentration determination in bulk undoped semi-insulating GaAs. Low temperature luminescence methods have long been employed for impurity identification, but no attempt to quantify luminescence in direct gap semiconductors has been published, despite considerable success employing quantitative luminescence in Si.