Investigation of surface and sub-surface defects on polished InP substrates using auger electron spectroscopy coupled to argon ion sputtering

Abstract

We show that Auger electron spectroscopy (AES) analysis in combination with in-situ observations in secondary electron (SE) mode alternating with argon ion sputtering (for example, in steps of ∼ 60 Å) can be successfully employed to detect and identify surface and sub-surface (∼ 1000 Å) defects on InP substrates. The case of a “ready-to-use” S-doped InP substrate is considered here as an example. Two sorts of defects classified as extrinsic and intrinsic have been detected. The former defects are identified as the impregnated particles of the polishing materials since they contained exclusively elements such as Ca, Cl, etc., the constituents of polish agents. The latter defects present at a low density, on the other hand, are presumed to have been generated in the crystal growth process since they are revealed by ion etching in the sub-surface region and contained excess of S dopant in some cases, and O in other cases in the form of In 2O 3.